How to use this renderer in my Three js scene

[Nandazdev]

Hello, thank you very much for the renderer, I would like to know how I could implement the renderer in my classroom like a module. I can't find any tutorials, I've searched the entire internet and I still haven't found how to use this incredible renderer.

[erichlof]

Hello @Nandazdev

Thank you for the kind words! Could you please give some more details about how you would like to use this renderer?

The original purpose of my Ray Tracing Renderer project is to show how classic 1980's and early 1990's ray tracing was done. In these early days of ray tracing, there were just a couple of lighting models, like Lambert for diffuse, Phong for specular, Whitted (and maybe Hall) for adding recursive reflections/refractions to the final image. Path tracing either hadn't been invented yet (Kajiya, 1986), or hadn't become mainstream yet in production rendering (not till early 2000's). Therefore, the final images produced from this classic, historical ray tracing have a unique, retro look (mainly due to Phong lighting) without all the distracting noise associated with more modern path tracing (in which a denoising system must be used).

This project was meant to be stand-alone, for demonstration purposes. Even though it uses a similar Three.js naming convention (like Three.js " " Renderer), I didn't really intend for it to be used like a drop-in renderer module for an existing larger project of the user. Having functionality like that would require a complete rewrite from the ground up, and much more additional planning and effort that I just can't devote to it at this time.

Having said that, I have tried to make the RayTracingCommon.js file more like a library, so that you can just #include the parts that you need from this large file, and then just call the desired functions in your shader that goes along with your own custom demo scene. For example, if you wanted to place a cylinder in your scene, you would just #include the 'raytracing_cylinder_intersect' ShaderChunk function and then call it in the shader code.

I tried to provide some basic examples of how to do this - have a look at the js and glsl files for the demos called Classic_Geometry_Showcase and Quadric_Shapes. These 2 demos show how to do all shapes possible, how to do basic lighting with reflections and refractions, how to do material roughness, and how to use basic texture mapping and UVs.

My advice on getting started would be to maybe copy one of those 2 demos and all their required files, into a new project folder. With all of my GitHub repos, I always make everything self-contained, so all the files that a demo needs are right here on this repo (there are no CDN downloads or NPM packages to worry about). Once you have an exact copy of one of my demos working on your own computer, just try changing some of the shapes around (size, color, material, etc), try positioning the camera at startup to a different starting location, change the starting camera FOV, add (#include and call its intersection function) and place a new shape that the particular demo does not already have, etc. This is the best way to learn what does what, and how you can control different parameters.

Best of luck with starting your own ray traced scenes! 😀

Cheers,
-Erich

[Nandazdev]

I never thought that someone as intelligent as you would answer me. Thank you very much. You are a very kind person. Thank you very much for your attention.

I followed the raytracing journey on YouTube and I really liked it. I was able to learn a lot, but it seems that the series is not finished. Thank you very much once again for the renderer and for your kindness 🙂.

Well, actually my project is: Create a blender, so I can say, what do you mean by blender, you ask? I want a renderer that renders the scene, objects from THREE JS itself.
I give an example of the blender renderer, C4D. These renderers render what is there in the scene, that's what I want. I found a renderer here on Git hub called MonteRay-main.
This renderer does exactly what I wanted, but it is very slow. I tried to create a raytracing following this video: https://youtu.be/Qz0KTGYJtUk?si=iAKP3OZrRz2OPt6W
This guy uses Unity to do this, and I think he uses a Shader material to create the raytracing, I could be wrong, I don't understand English very well.
But I would like to create my raytracing like in this video using an object from THREE JS itself.

Thank you for your attention 🙂

[erichlof]

Ahh yes, I understand better now what you're trying to do. Thank you for the video link - that is Sebastian Lague, I have watched almost every video from him. His visualizations are amazing and inspiring (which is why he has over a million subscribers, ha). Yes you're right - he uses Unity for his ray/path tracing projects. I know this because on every other video, he mentions his Unity editor. Yes, to do ray tracing or path tracing in a program like Unity, and for Three.js too, you can't just use the built-in renderer that comes with the framework or game engine. You kind of have to side-step the traditional rasterization pipeline, and instead use a full screen quad (2 huge side-by-side triangles) that you write a ray tracing shader for.

Traditional rasterization is a scene object-first approach, while ray tracing is a pixel-first approach. In the traditional pipeline, you define a scene with objects, then all the objects' triangles get sent to the GPU, where, after projecting the view to your 2D screen, the fragment shader operates on any pixels that happen to cover any objects and their triangles. So if you had a little ball in the middle of the screen, the fragment shader will only color or light any pixels that cover the ball - the rest of the outside pixels will get passed over, and will not get run on the fragment shader. So this is the object-first, pixel-last approach.

Now at the other extreme, a ray tracer first defines 2 large triangles that form a screen-size quad that remains fixed for the duration of the app. Remember we said that the fragment shader will run any time it sees a pixel that is on top of a triangle - well, we have 'short-circuited' this feature in a way: now, when it searches for pixels covering triangles, ALL the pixels on screen are on top of at least 1 large triangle, because the 2 triangles cover the whole screen! So the fragment shader is 'forced' to work on each and every pixel of the screen, and GPUs don't mind this, as they work in parallel. Then we shoot out a bunch of rays at the same time from the camera, through each pixel, and out into the scene. Only now do we define the scene and all the objects that we want to be in the scene - see how this is backwards from rasterization? That's why ray tracing is a pixel-first, object-last approach, that is suitable for the GPU, because we want it done in parallel.

So having all this in mind, we run into the 1st issue when trying to do what you are wanting to do, which is like a ray tracing renderer operating inside a rasterization editor program, like Blender, Unity, or the Three.js web-based editor. Sure, we can easily define a scene, or even load in a scene that we downloaded, and all 3 editors will immediately display these scenes, no matter how many objects are in the scenes (remember the object-first approach). And let's say you were able to make a full screen quad and hook up a shader to it that runs for all pixels at the same time. But, if you want to now ray trace this exact scene from the same viewpoint, how do we define the same scene, for ray-intersection functions in the shader?

On the video, Sebastian briefly talks about this problem, because traditional scene spheres are made up of many small triangles (in order to look smooth), and if you try to brute force ray trace even 1 sphere, it will slow down the ray tracer to a crawl. So instead, he got around the problem by defining a ray-sphere math function in the shader, which efficiently traces spheres of any size and anywhere in the scene. Again, you can't go crazy with it, because as soon as you have like 30 spheres or more, your program will again slow way down.

From here, the only option to keep things fast, is to have acceleration structures like the BVH, for every triangle mesh, (or over all the spheres, if you have thousands of them in your scene). I have been successful with implementing 1 BVH for a large triangular model, but if you were to download a random scene in glTF format for example, it could have dozens or hundreds of triangle models, each requiring their own BVH to get through all the triangles! At this point, you would need to have a large upper-level BVH that groups together the smaller, individual BVHs for each mesh - this gets really complicated and slow fairly quickly as the scene grows in complexity (but it is the approach taken by NVIDIA when you see an 'RTX ON' demo). They use their own proprietary system for building the upper and lower level BVHs for every triangle (could be millions), and the end-user must have a beefy RTX graphics card, in order to run these ray tracing systems fast enough.

So this was a really long way of saying that unfortunately, my renderer is not ready to do this - loading in any arbitrary glTF scene, or create your own scene inside an editor, and then magically have it ray traced - I'm just not there yet, not even close, ha.

I don't mean to be discouraging with your vision, but I just want to keep it realistic. If you wanted to make a simple scene converter (like for simple spheres, boxes, etc only), that would be totally possible, and a good place to start. But if you're wanting to load in more interesting scenes with dozens of models, each with thousands of triangles, then the effort would be massive - and I don't even know if WebGL would be able to handle so much data. But who knows, the web technology is evolving all the time and GPUs are getting faster as well.

Hope this helps (apologies if you knew some this material already - I just like to start from scratch when discussing topics like this). 😊

Cheers,
-Erich

[Nandazdev]

Thank you very much for the explanation, it was very well explained, congratulations 😀

I agree with you that creating a raytracing algorithm by crazy means would not be practical at all. I have been able to follow some raytracing projects and I have noticed that most of them use BVH to obtain a certain optimization of the raytracing process.

Well, I already knew that this journey would not be simple, now I have realized how complex the raytracing algorithm is!

I have been researching raytracing for 4 years and even so it is clear that I am still far from the goal. I would really like to create an algorithm like this so that I can share the knowledge in schools. Many children/teenagers are impressed when they see a super realistic object on the computer and they ask me how did you do that? 😅 I have no answer.

Thank you for the explanation, it was useful. I wasn't discouraged by the explanation, but now I realize what I'm getting myself into. Creating this algorithm has been a dream for as long as I can remember.
But I don't believe I'll be able to create this algorithm. It's a sad reality, but it's better to live in reality than in an illusion. I really won't be able to create raytracing, at least not now.
I need to study a lot.

I thought I could use the basic Three JS renderer together with the GLSl shader to create raytracing, but I think I'm wrong. I believed I could do it this way.

What do you recommend I do now?

I really don't know which way to go. I'm actually lost. Is there any good material/series that covers all the topics you mentioned?

If there is anything, I would really appreciate your help.

My journey is long, I have to do this in my software:
• Raytracing-renderer
• Functionality to animate models
• Modeling
• Texturing
• Model sculpting

I don't know if I'll be able to do it because in the first stage I'm taking a lot of time.

Sorry if some words are wrong, I'm a Portuguese speaker and I'm using a translator to translate into English.

Anyway! Thank you very much for the explanation you gave, it's like a wake-up call to see reality.

Thank you very much for your attention 🙂

[erichlof]

Hello again, @Nandazdev !

Apologies for the late reply - my little Toshiba laptop that I've used for over 16 years (and where I coded every single line of all my projects on GitHub), finally died on me yesterday. It was a hard drive failure, couldn't even get my local tech to boot it up anymore.

Please give me another day to put together a response to your last message. You had lots of good stuff in there so I want to be able to reply thoughtfully to everything.

Will be back very soon with my reply and suggestions. 😊

-Erich

[Nandazdev]

Olá @erichlof lamento muito pelo o ocorrido.

Espero que você consiga resolver o problema.
É muito gentil da sua parte por te importares com isso. Fico inteiramente grato por te importares em me fornecer uma resposta explicativa e completa, muito obrigado.

Que tudo fique bem, estarei aqui a espera 🙂

[erichlof]

Hello @Nandazdev I'm back! 😀

I have ordered a new thin laptop (same compact size as my old one) and it's on the way - should be here in a week or so. It has more modern standards of processing speed, RAM, and a decent graphics card - so hopefully I will get another 10 (or 16, ha) years out of this one! 😅

Thank you for clarifying your goals and purpose for diving into ray tracing. It helps me with my response and suggestions for moving forward. You had mentioned this list that you would eventually like to accomplish:

• Raytracing-renderer
• Functionality to animate models
• Modeling
• Texturing
• Model sculpting

So now I see that the renderer is just the first part, or the first stepping stone, in your ultimate graphics journey. I'll start off with an admission: I have been on that 1st bullet point for over a decade, with no plans on moving to the next topic! 😆 Seriously, if there's one thing I've learned about ray tracing since I started learning it back in 2014, it's this: you can literally spend a lifetime (or at least a career lifetime) on the subject and techniques of ray tracing!

Ray tracing has been around almost as long as rasterization, so it has a rich, 55 year history. In that time, so many advancements have been made, like recursive reflections/refractions (Whitted, 1979), randomized rays (Cook, 1984), path tracing (Kajiya, 1986), effecient material and light sampling (Veach and Shirley, early 1990s), real time ray/path tracing (Bikker, 2010s), denoising and AI frame reconstruction (NVIDIA research, last 5 years), BVH advancements (also NVIDIA, last 5 years), etc. Especially when AI was introduced into the ray tracing algorithm, things have been moving ever faster - it's almost impossible to keep up with the advancements and new research coming out.

I've been thinking about what advice to give you, now that you have clarified your goals, and you are sort of in a "fork in the road", wondering which path to follow. Of course, I don't know your complete situation and your ability to take on new areas of study, but my advice would be: take both roads at the same time! In other words, there's no reason why you can't explore both the Ray Tracing-only path, and the more traditional rasterization path (like vanilla Three.js), in order to work your way down through your bullet list.

Let me rewind a bit and share a little of my personal history with learning different computer topics. When I was 11 years old or so, my dad bought me my first home computer, which was a Commodore 64 (I know, I'm old 😅). From the very first moment I made it
10 PRINT "Hello"
20 GOTO 10
I knew I was hooked for life! It was amazing to me that I had control over what was displayed on a computer screen. From there, I bought computer magazines that featured full program listings in Basic, that you could sit down and copy, line by line, and run them and see what happened. Most of the fun looking graphics program listings used Assembly though, so I didn't understand at all what I was typing in! Meanwhile I had been playing the piano since 5 years old, and music was my first love and I knew I wanted to pursue that as my profession. So throughout high school and college, I devoted all my time to playing music and teaching music, and I still perform and teach music as a living today. But in the background, there was that curiosity for computers and graphics that kept me coming back. So after graduating college, my younger brother (who was still in high school), showed me some small programs for DOS that he had done for his high school elective computer class, using the Pascal programming language. Although his little programs were cool, I asked if he and I could try making a simple 2D game, and maybe I could look over his shoulder and learn how to do some Pascal at the same time. The moment we had a little white box on the screen that could move when you pressed the arrow keys - for the 2nd time in my life, I knew I was hooked! This time it was game programming. Even though my brother didn't really enjoy it as much as me, I really jumped in and learned more topics related to graphics and games programming, starting with the C programming language, then basic Windows init and management (this was Windows 98, lol), and eventually OpenGL programming (OpenGL 1.1 back then). Now we're up to 1998, and it was at this point where I was where you are right now. Game programming is another huge area of computer science (even bigger than ray tracing), with many paths to choose from. I remember feeling a little cautious like you do now, because I didn't want to go down a "wrong" path and waste my learning time.

But I've realized over the years that there is no "wrong" path, or "optimal" path to learning programming and graphics. All paths and all areas you choose to study are correct. I don't use C for Windows-only programming anymore, but I'm glad I went down that path, because it taught me to be responsible in terms of memory management, keeping a watchful eye on performance, and always knowing what you are typing into your codebase and understanding what and why it's doing what it does. And even though I mainly do ray tracing nowadays, I still enjoy 3D game programming and making small games with small scope, that run fast in the browser. And all the math that I had to learn in order to make 3D engines back in the 1990's, really helped when I wanted to move the camera or move objects in my ray traced scenes and projects.

Sorry for that trip down my memory lane, but hopefully you can see that everything that you choose to study is related. For example, if you choose to learn more about BVHs, this may help your understanding of geometry and how mesh data is stored, and how we can efficiently store and access large amounts of geometry and material data - which may help down the line when you want to move on to the next bullet points in your list, like animating models and modeling in general. You'll have more of an understanding of what a ray tracing engineer would like to see when it comes to importing and rendering meshes, and how they would like to have the data stored for fast access and retrieval. Another example from my personal projects is that Im working on a game where you can drive a futuristic hovering glider around a 3d curved track. In order to not have the vehicle clip through the curved course, there needs to be some kind of ray casting for the physics to behave correctly. Well, since I have been doing ray tracing and ray-object intersection functions for years now, i knew exactly what needed to be implemented, and more importantly, I already had the code and algorithms lying around my other codebases, so I added physics raycasting in one afternoon without too much trouble. Those are just a couple examples of hundreds that I can think of, where different areas of study can help each other.

Now getting more specific for your personal goals, I would recommend that you maybe split your ultimate dream project into 2 projects: 1 project for just ray tracing (where 60 fps is not a concern, just that it looks the best that it can), and 1 project for everything else on your list (where you are not concerned how the graphics get displayed, you just let Three.js or WebGL handle it with traditional rasterization - which is blazing fast and efficient).

You had mentioned that you would like to be able to use ray tracing in a classroom environment, and that you would like to be able to explain to young students how the ray tracing is being displayed on the screen. If you just devoted time to a ray tracing-only project, then you could better show others your techniques with small-scoped, focused demos. I think you said that you already have worked through Peter Shirley's Ray Tracing in One Weekend book (that would be my top recommendation to anyone wanting to learn how to do ray tracing), maybe you could work through his next volume - there are 3 books in his series: they range from beginning, to intermediate, to advanced for the 3rd book. Again, performance and 60fps should not be a concern in the beginning, just getting everything to look right should be the goal. Then maybe down the road, you can add some interactivity to it with mouse and keyboard movements, and then eventually move everything to the GPU to make it run in real-time, with 60 fps, cutting corners for performance, and efficiency becoming the new goals. Hopefully after doing a basic, non-realtime CPU ray tracer, you'll be able to handle any questions from your students (like, "how did you get that metal surface to be reflective?"). One more bit of advice from my experience of teaching music, is that it's ok to say to a younger person, "I don't know". "But the next time I see you, I will try to have an answer for you"! It's tempting to pretend like we know what we're talking about all the time, especially when they're paying you to teach them, and I'm guilty of this myself. But one of the best ways to learn something, really learn it, is to be able to go off and assemble the pieces, rearrange them if need be, filter the info for the age group that your explaining to, and then boil it down to an answer that both you and your student can be satisfied with. This is why I think that a dedicated, ray-tracing only renderer would be a fun and beneficial project for your overall graphics journey.

As far as the other project, maybe just focus on 1 topic for a while, then move on to something else, all while staying within your 2nd project framework and codebase (the real-time, rasterization project). Let three.js or WebGL (or even Unity for that matter) handle the UI, input, graphics heavy lifting of pushing millions of triangles to the screen, while you are freed up to focus on animation, modeling, data storage and transfer, materials, and textures. Unlike the ray-tracing only project, this project should target 30-60 fps and be smooth and interactive for the user - so performance and a smooth user experience is always a concern.

Now even though these would be 2 totally different projects, with different concerns, constraints, and goals, it is possible that they could merge down the road on your overall journey. For example, maybe you could take a ray intersection function and apply it to the real-time engine for physics raycasting (as I previously mentioned). Or you could bring some of the smooth input handling from the real-time project over to the slow ray tracer, but as a small preview window that runs in real time (like Blender does with Cycles, I think). Or you could bring one of your efficiently stored models over to the ray tracer and try to do a beauty final render that doesn't take so long (because of the efficient way that you represented your models). You could even do a "hybrid" renderer, where you take the classic ideas of ray tracing, like mirror reflection, and implement a function that does screen space reflections with traditional rasterized triangles. The possible connections are endless.

Sorry for getting so long-winded again with my reply 😅, but you had brought up some really good points that deserved thoughtful responses. I hope some of these responses have helped you make a plan for your journey moving forward. As always, feel free to clarify further, or ask anything- I'll try to answer to the best of my ability. I think it's great that you are wanting to learn more about ray tracing and 3D graphics in general - and even greater that you are wanting to share your knowledge and passion with your students and other curious kids around you. Maybe they will be inspired by you to start their own computer graphics journeys!

Cheers,
-Erich

[Nandazdev]

Dê uma olhada:

<title>Cornell Box Raytracing</title> <style> body { font-family: Arial, sans-serif; margin: 20px; background: #000000; color: #FFFFFF} #renderStatus { padding: 10px; background: #FFFFFF00;

        margin-top: 10px;
        border-radius: 10px;
    }
    canvas {
        border: 1px solid #333;
    }
</style>

Cornell Box Raytracing com Reflexões

Preparando renderização...

<script>

const canvas = document.getElementById('myCanvas');
const ctx = canvas.getContext('2d');
const statusDiv = document.getElementById('renderStatus');

// Tamanho do canvas - proporção quadrada para Cornell Box
canvas.width = 500;
canvas.height = 500;
const width = canvas.width;
const height = canvas.height;
const aspectRatio = width / height;

// Configurações do renderizador
const samplesPerPixel = 800; // Amostras por pixel em cada tile
const maxDepth = 5; // Profundidade máxima de reflexões
const tileSize = 100; // Tamanho dos blocos de renderização
let currentTileX = 0;
let currentTileY = 0;
let tilesX = Math.ceil(width / tileSize);
let tilesY = Math.ceil(height / tileSize);
let renderStartTime = null;
let finalImage = null;

// Classe de vetor 3D
class Vec3 {
constructor(x, y, z) {
this.x = x || 0;
this.y = y || 0;
this.z = z || 0;
}

add(v) { return new Vec3(this.x + v.x, this.y + v.y, this.z + v.z); }
sub(v) { return new Vec3(this.x - v.x, this.y - v.y, this.z - v.z); }
mul(s) { return new Vec3(this.x * s, this.y * s, this.z * s); }
div(s) { return new Vec3(this.x / s, this.y / s, this.z / s); }
dot(v) { return this.x * v.x + this.y * v.y + this.z * v.z; }
cross(v) { 
    return new Vec3(
        this.y * v.z - this.z * v.y,
        this.z * v.x - this.x * v.z,
        this.x * v.y - this.y * v.x
    );
}
length() { return Math.sqrt(this.dot(this)); }
normalize() { 
    const len = this.length();
    return len > 0 ? this.div(len) : new Vec3();
}
min(b) { return new Vec3(Math.min(this.x, b.x), Math.min(this.y, b.y), Math.min(this.z, b.z)); }
max(b) { return new Vec3(Math.max(this.x, b.x), Math.max(this.y, b.y), Math.max(this.z, b.z)); }
reflect(normal) {
    return this.sub(normal.mul(2 * this.dot(normal)));
}

}

// Classe base para objetos
class Hittable {
hit(ray, tMin, tMax) {
return null;
}
}

// Classe de material
class Material {
constructor(color, emission = 0, reflectivity = 0) {
this.color = color;
this.emission = emission;
this.reflectivity = reflectivity; // 0 = difuso, 1 = totalmente reflexivo
}
}

// Classe de esfera
class Sphere extends Hittable {
constructor(center, radius, material) {
super();
this.center = center;
this.radius = radius;
this.material = material;
}

hit(ray, tMin, tMax) {
    const oc = ray.origin.sub(this.center);
    const a = ray.direction.dot(ray.direction);
    const b = oc.dot(ray.direction);
    const c = oc.dot(oc) - this.radius * this.radius;
    const discriminant = b * b - a * c;

    if (discriminant > 0) {
        const temp = (-b - Math.sqrt(discriminant)) / a;
        if (temp < tMax && temp > tMin) {
            const point = ray.origin.add(ray.direction.mul(temp));
            const normal = point.sub(this.center).div(this.radius);
            return {
                t: temp,
                point: point,
                normal: normal,
                material: this.material
            };
        }

        const temp2 = (-b + Math.sqrt(discriminant)) / a;
        if (temp2 < tMax && temp2 > tMin) {
            const point = ray.origin.add(ray.direction.mul(temp2));
            const normal = point.sub(this.center).div(this.radius);
            return {
                t: temp2,
                point: point,
                normal: normal,
                material: this.material
            };
        }
    }
    return null;
}

}

// Classe de cubo
class Cube extends Hittable {
constructor(min, max, material) {
super();
this.min = min;
this.max = max;
this.material = material;
}

hit(ray, tMin, tMax) {
    let tmin = (this.min.x - ray.origin.x) / ray.direction.x;
    let tmax = (this.max.x - ray.origin.x) / ray.direction.x;
    
    if (tmin > tmax) [tmin, tmax] = [tmax, tmin];
    
    let tymin = (this.min.y - ray.origin.y) / ray.direction.y;
    let tymax = (this.max.y - ray.origin.y) / ray.direction.y;
    
    if (tymin > tymax) [tymin, tymax] = [tymax, tymin];
    
    if ((tmin > tymax) || (tymin > tmax)) return null;
    
    if (tymin > tmin) tmin = tymin;
    if (tymax < tmax) tmax = tymax;
    
    let tzmin = (this.min.z - ray.origin.z) / ray.direction.z;
    let tzmax = (this.max.z - ray.origin.z) / ray.direction.z;
    
    if (tzmin > tzmax) [tzmin, tzmax] = [tzmax, tzmin];
    
    if ((tmin > tzmax) || (tzmin > tmax)) return null;
    
    if (tzmin > tmin) tmin = tzmin;
    if (tzmax < tmax) tmax = tzmax;
    
    if (tmin < tMax && tmin > tMin) {
        const point = ray.origin.add(ray.direction.mul(tmin));
        
        let normal = new Vec3();
        const epsilon = 0.0001;
        
        if (Math.abs(point.x - this.min.x) < epsilon) normal = new Vec3(-1, 0, 0);
        else if (Math.abs(point.x - this.max.x) < epsilon) normal = new Vec3(1, 0, 0);
        else if (Math.abs(point.y - this.min.y) < epsilon) normal = new Vec3(0, -1, 0);
        else if (Math.abs(point.y - this.max.y) < epsilon) normal = new Vec3(0, 1, 0);
        else if (Math.abs(point.z - this.min.z) < epsilon) normal = new Vec3(0, 0, -1);
        else if (Math.abs(point.z - this.max.z) < epsilon) normal = new Vec3(0, 0, 1);
        
        return {
            t: tmin,
            point: point,
            normal: normal,
            material: this.material
        };
    }
    
    return null;
}

}

// Classe de plano retangular (para as paredes da Cornell Box)
class Rectangle extends Hittable {
constructor(min, max, normal, material) {
super();
this.min = min;
this.max = max;
this.normal = normal.normalize();
this.material = material;

    // Determinar qual é o plano (x, y ou z constante)
    if (Math.abs(this.normal.x) > 0.9) this.planeType = 'yz';
    else if (Math.abs(this.normal.y) > 0.9) this.planeType = 'xz';
    else this.planeType = 'xy';
    
    // O valor constante do plano
    if (this.planeType === 'yz') this.k = min.x;
    else if (this.planeType === 'xz') this.k = min.y;
    else this.k = min.z;
}

hit(ray, tMin, tMax) {
    let t;
    
    // Calcular a interseção com o plano
    if (this.planeType === 'yz') {
        if (Math.abs(ray.direction.x) < 0.0001) return null;
        t = (this.k - ray.origin.x) / ray.direction.x;
    } else if (this.planeType === 'xz') {
        if (Math.abs(ray.direction.y) < 0.0001) return null;
        t = (this.k - ray.origin.y) / ray.direction.y;
    } else {
        if (Math.abs(ray.direction.z) < 0.0001) return null;
        t = (this.k - ray.origin.z) / ray.direction.z;
    }
    
    if (t < tMin || t > tMax) return null;
    
    // Calcular o ponto de interseção
    const point = ray.origin.add(ray.direction.mul(t));
    
    // Verificar se o ponto está dentro do retângulo
    if (this.planeType === 'yz') {
        if (point.y < this.min.y || point.y > this.max.y || 
            point.z < this.min.z || point.z > this.max.z) return null;
    } else if (this.planeType === 'xz') {
        if (point.x < this.min.x || point.x > this.max.x || 
            point.z < this.min.z || point.z > this.max.z) return null;
    } else {
        if (point.x < this.min.x || point.x > this.max.x || 
            point.y < this.min.y || point.y > this.max.y) return null;
    }
    
    return {
        t: t,
        point: point,
        normal: this.normal,
        material: this.material
    };
}

}

// Classe Ray
class Ray {
constructor(origin, direction) {
this.origin = origin;
this.direction = direction;
}
}

// Configuração da cena Cornell Box
const objects = [
// Parede traseira (branca)
new Rectangle(
new Vec3(-1, -1, -2),
new Vec3(1, 1, -2),
new Vec3(0, 0, 1),
new Material({r: 255, g: 255, b: 255}, 0, 0)
),

// Parede esquerda (vermelha)
new Rectangle(
    new Vec3(-1, -1, -2),
    new Vec3(-1, 1, 0),
    new Vec3(1, 0, 0),
    new Material({r: 255, g: 255, b: 255}, 0, 0)
),

// Parede direita (verde)
new Rectangle(
    new Vec3(1, -1, -2),
    new Vec3(1, 1, 0),
    new Vec3(-1, 0, 0),
    new Material({r: 255, g: 255, b: 255}, 0, 0)
),



// Chão (branco)
new Rectangle(
    new Vec3(-1, -1, -2),
    new Vec3(1, -1, 0),
    new Vec3(0, 1, 0),
    new Material({r: 255, g: 255, b: 255}, 0, 0)
),


// Esfera refletiva (espelho)
new Sphere(
    new Vec3(-0.50, -0.6, -1.2),
    0.4,
    new Material({r: 255, g: 185, b: 1}, 0, 0.4)
),

new Sphere(
    new Vec3(0.50, -0.6, -1.2),
    0.4,
    new Material({r: 255, g: 255, b: 255}, 0, 0.9)
),

// Cubo (difuso branco)
new Cube(
    new Vec3(-1, 1, -1.5),
    new Vec3(0.9, 1, -1),
    new Material({r: 200, g: 200, b: 255}, 100000, 0.0)
)

];

function random(min, max) {
return min + Math.random() * (max - min);
}

function randomInHemisphere(normal) {
const inUnitSphere = new Vec3(
random(-1, 1),
random(-1, 1),
random(-1, 1)
).normalize();
return inUnitSphere.dot(normal) > 0 ? inUnitSphere : inUnitSphere.mul(-1);
}

// Função principal de raytracing com suporte a reflexão
function traceRay(ray, depth = 0) {
if (depth > maxDepth) return {r: 0, g: 0, b: 0};

let closestHit = null;
let closestT = Infinity;

// Testar interseção com todos os objetos
for (const obj of objects) {
    const hit = obj.hit(ray, 0.001, closestT);
    if (hit) {
        closestT = hit.t;
        closestHit = hit;
    }
}

if (closestHit) {
    const material = closestHit.material;
    
    // Objeto emissor de luz
    if (material.emission > 0) {
        return {
            r: material.color.r * material.emission / 255,
            g: material.color.g * material.emission / 255,
            b: material.color.b * material.emission / 255
        };
    }

    // Calcular reflexão
    let attenuationColor = {r: 0, g: 0, b: 0};
    
    if (material.reflectivity > 0) {
        // Direção refletida
        const reflected = ray.direction.reflect(closestHit.normal);
        const reflectionRay = new Ray(closestHit.point, reflected);
        const reflectColor = traceRay(reflectionRay, depth + 1);
        
        // Combinar reflexão especular
        attenuationColor = {
            r: material.color.r / 255 * material.reflectivity * reflectColor.r,
            g: material.color.g / 255 * material.reflectivity * reflectColor.g,
            b: material.color.b / 255 * material.reflectivity * reflectColor.b
        };
    }
    
    // Calcular componente difusa
    if (material.reflectivity < 1.0) {
        const diffuseAmount = 1.0 - material.reflectivity;
        const target = closestHit.point.add(closestHit.normal).add(randomInHemisphere(closestHit.normal));
        const diffuseRay = new Ray(closestHit.point, target.sub(closestHit.point).normalize());
        const diffuseColor = traceRay(diffuseRay, depth + 1);
        
        // Combinar com luz difusa
        const diffuseAttenuation = 1.8; 
        attenuationColor = {
            r: attenuationColor.r + material.color.r / 255 * diffuseAmount * diffuseAttenuation * diffuseColor.r,
            g: attenuationColor.g + material.color.g / 255 * diffuseAmount * diffuseAttenuation * diffuseColor.g,
            b: attenuationColor.b + material.color.b / 255 * diffuseAmount * diffuseAttenuation * diffuseColor.b
        };
    }
    
    return {
        r: Math.min(1, attenuationColor.r),
        g: Math.min(1, attenuationColor.g),
        b: Math.min(1, attenuationColor.b)
    };
}

// Fundo (cor ambiente - preto para Cornell Box)
return {
    r: 0.6,
    g: 0.6,
    b: 0.6  
};

}

// Inicializa buffer de imagem
function initImageBuffer() {
finalImage = ctx.createImageData(width, height);
for (let i = 0; i < finalImage.data.length; i += 4) {
finalImage.data[i] = 0; // R
finalImage.data[i + 1] = 0; // G
finalImage.data[i + 2] = 0; // B
finalImage.data[i + 3] = 255; // A
}
renderStartTime = performance.now();
}

// Atualiza o status de renderização
function updateStatus() {
const elapsed = ((performance.now() - renderStartTime) / 1000).toFixed(1);
const totalTiles = tilesX * tilesY;
const tilesCompleted = currentTileY * tilesX + currentTileX;
const progress = ((tilesCompleted / totalTiles) * 100).toFixed(1);
statusDiv.textContent = Renderizando: ${progress}% | Tile: [${currentTileX + 1}/${tilesX}, ${currentTileY + 1}/${tilesY}] | Tempo: ${elapsed}s;
}

// Renderiza um único tile
function renderTile() {
// Posição da câmera para visualizar a Cornell Box
const camera = new Vec3(0, 0, 2);
const data = finalImage.data;

// Calcular limites do tile atual
const startX = currentTileX * tileSize;
const startY = currentTileY * tileSize;
const endX = Math.min(startX + tileSize, width);
const endY = Math.min(startY + tileSize, height);

// Desenhar borda do tile atual
ctx.strokeStyle = '#00FF00';
ctx.lineWidth = 2;
ctx.strokeRect(startX, startY, endX - startX, endY - startY);

// Renderizar pixels do tile atual
for (let y = startY; y < endY; y++) {
    for (let x = startX; x < endX; x++) {
        let pixelColor = {r: 0, g: 0, b: 0};
        
        // Amostragem múltipla para anti-aliasing
        for (let s = 0; s < samplesPerPixel; s++) {
            const u = (x + Math.random()) / width;
            const v = (y + Math.random()) / height;
            const rayDir = new Vec3(
                aspectRatio * (2.0 * u - 1.0),
                1.0 - 2.0 * v,
                -1.0
            ).normalize();
            
            const sampleColor = traceRay(new Ray(camera, rayDir));
            pixelColor.r += sampleColor.r;
            pixelColor.g += sampleColor.g;
            pixelColor.b += sampleColor.b;
        }
        
        // Média das amostras
        pixelColor.r /= samplesPerPixel;
        pixelColor.g /= samplesPerPixel;
        pixelColor.b /= samplesPerPixel;
        
        // Correção gamma simples
        pixelColor.r = Math.sqrt(pixelColor.r);
        pixelColor.g = Math.sqrt(pixelColor.g);
        pixelColor.b = Math.sqrt(pixelColor.b);
        
        const idx = (y * width + x) * 4;
        data[idx] = Math.floor(pixelColor.r * 255);
        data[idx + 1] = Math.floor(pixelColor.g * 255);
        data[idx + 2] = Math.floor(pixelColor.b * 255);
    }
}

// Atualizar o canvas com os dados renderizados
ctx.putImageData(finalImage, 0, 0);

// Avançar para o próximo tile
currentTileX++;
if (currentTileX >= tilesX) {
    currentTileX = 0;
    currentTileY++;
}

updateStatus();

// Verificar se todos os tiles foram renderizados
if (currentTileY < tilesY) {
    // Continuar renderizando o próximo tile
    setTimeout(renderTile, 10); // Pequeno delay para atualização da UI
} else {
    // Renderização completa
    const totalTime = ((performance.now() - renderStartTime) / 1000).toFixed(1);
    statusDiv.textContent = `Renderização completa em ${totalTime}s`;
}

}

// Inicia a renderização
function startRendering() {
// Limpar canvas
ctx.fillStyle = '#000';
ctx.fillRect(0, 0, width, height);

// Inicializar buffer de imagem e começar a renderizar
initImageBuffer();
renderTile();

}

window.addEventListener('load', startRendering);

</script>

[Nandazdev]

Hey, long time no see!
Sorry for the delay in replying — I was really focused on my electrical engineering course. But I’m back now, even though my time is limited. Still, it’s enough to share a few thoughts.

In the example I sent earlier, I built an offline renderer using the canvas 2D context. I used plain JavaScript (CPU-based) for ray-object intersection. And honestly, it's pretty fast — well, for spheres, cubes, and planes, it performs nicely.
However, I already expect that once I implement intersections with high-poly objects (with lots of triangles), performance will take a hit.

I already have a clear idea of how I want to integrate ray tracing into my Three.js workflow, so here’s a quick breakdown:

In Three.js, each object I create will be stored in an array with its position, scale, rotation, and material.

The camera data will also be stored: position, rotation, and field of view.

The ray tracer will render everything in a dedicated canvas — Three.js will act purely as the editor.

The ray tracer will take all the saved data, recreate the scene objects and camera, and render them accordingly.

So, in short: Three.js will serve only as an editor, while the canvas called myRender will handle all ray tracing.

This is actually the same approach I use in my 2D game engine: I build the editor using a canvas, and when the game is run, it only loads the saved object data, which is then handled by PhaserJS.

I believe this setup will make everything much simpler, especially since my renderer is offline and doesn’t need to be real-time.

Best regards,
Nandaz Dev

[erichlof]

@Nandazdev

Hello! No worries about the delay - I figured you were busy with work or school. Glad you were able to find some time to work on your ray tracing project - and thank you for sharing your code here with me. It helps me a lot with knowing where you're coming from and what you want to do in the future with your project.

So far as the code goes, it looks really solid! I didn't see anything that was out of place. You did a great job porting Peter Shirley's Ray Tracing in One Weekend code from C++ to JavaScript. I know that can be a real challenge! 😅

If I am reading your last post correctly, you would like to do all the scene objects and camera setup code in the Three.js framework, rather than with your own JavaScript utility functions and classes that you've ported from the Ray Tracing in One Weekend book - do I have that correct? If so, I think you will enjoy using Three.js as the host framework for scene management, because it already has a complete Vector and Matrix math library built in, as well as helpful utilities like 'dot', 'cross', 'normalize', 'min', 'max', 'randomInRange(min,max)', 'reflect', etc. So you can rely on Three.js' well-tested library to do all the heavy lifting when it comes to Vector and Matrix math and scene management.

There are a couple of nuanced issues though, when deciding how to represent your scene objects, their transforms, and their materials. For instance, let's say you add a simple cube to your scene. The normal Three.js way is to first declare a geometry, then declare a material, then declare a mesh that will combine these 2 elements together. So you could declare a let geometry = new THREE.BoxGeometry as the type of shape you would like, then maybe a let material = new THREE.MeshStandard material where you can set the color, emissive, roughness, metalness, etc., and then a new Mesh, something like:
let BoxMesh = new THREE.Mesh(geometry, material);
BoxMesh.position.set(0, 5, -10);
BoxMesh.scale.set(5,5,5);
BoxMesh.rotation.set(0, 0.3, 0); / * rotate slightly around the Y axis * /
BoxMesh.updateMatrixWorld(); / * don't forget this when changing an object's transform, otherwise the changes will be forgotten by Three.js when it's time to actually render the object * /

And you're good to go (if you were just doing regular vanilla Three.js rasterization rendering). However, inside the ray tracing loop that intersects all of the objects in your scene, you will need a way of parsing through all of the objects, one by one, and getting their geometry and their materials, as well as using their transforms when doing the raycasting against them. The first two are doable, you just need to see what kind of geometry your dealing with for each object - in our case it will be of type THREE.BoxGeometry. Then you need to know what intersection function routine to call for each object, based upon what kind of Geometry it is made from. So in our case again, we would call the box 'intersect()' function that you created in JavaScript. The transform is the most tricky to deal with. Unless you want all uniform scaled objects (perfect cubes (no stretched boxes), perfect sheres (no ellipsoids)), that have no rotations, you will have to find a way to apply the inverse of each object's Matrix to the ray origin and ray direction, before you can call 'intersect' on that object. This will correctly rotate, scale, and position each object so that it respects your scene description back in your JavaScript setup code.

If you need help making this technique work (called object 'Instancing' btw), check out my Cornell Box demos over on my PathTracing Renderer GitHub repo and it will demonstrate line by line how it's done. If you're still confused after looking at my examples, feel free to ask me anything about that process and I will try to help.

The reason I mentioned these future issues that you might have to deal with, is because I can't remember if Peter Shirley covers this topic in his 1st volume of the Ray Tracing in One Weekend series. From the looks of your intersection functions, it seems that he might just intersect each object with the parameters that are passed into the functions, like position, radius, minCorner, maxCorner, etc. Even though this works great when you are starting out, it won't help when you need to non-uniformly scale an object, or rotate that object. For those kinds of transforms, you really need the inverse Matrix trick.

Just let me know where you need help, if it all. It looks like you're already off to a great start! Best of luck in the next steps! 😊

-Erich

[Nandazdev]

Greetings, I'm back with little time again because of the electrical engineering course 😅 I'm running out of time. But we've made some progress. Since I'm a Portuguese speaker, it's really hard to understand the raytracing books, but I'm getting better at it. I don't know if I'll be able to complete my project right now, but I believe I will. Thank you very much for the motivation, your story that you told me gave me hope in a lot of things, I feel like I can do it, if someone else did it, I can too, if no one else did it, I'll do it, that's what I'm thinking now. Man, believe me, you changed my life, motivating me. I've made a lot of progress: I won't go into detail, but I'll force the code and take some screenshots, I believe it will get better with time.

// Configuração do Three.js (myCanvas)
const renderer = new THREE.WebGLRenderer({
canvas: document.getElementById('myCanvas'),
antialias: true
});
renderer.setClearColor(0x1E1E1E);
renderer.setSize(window.innerWidth, window.innerHeight);

const scene = new THREE.Scene();
const camera = new THREE.PerspectiveCamera(95, window.innerWidth / window.innerHeight, 0.1, 2000);
camera.position.set(-70, 80, 100);

// Adicionar grid helper
const gridHelper = new THREE.GridHelper(1000, 100, 0x422525, 0x252525);
scene.add(gridHelper);

// Criar objetos da cena

const geometry = new THREE.BoxGeometry(1, 1, 1);
const material = new THREE.MeshStandardMaterial({
color: 0x4477ff,
flatShading: true
});

const material2 = new THREE.MeshStandardMaterial({
color: 0x5E00FF,
flatShading: true
});

const material3 = new THREE.MeshStandardMaterial({
  color: 0xFF0068,
  flatShading: true
});



const cube2 = new THREE.Mesh(geometry, material2);
cube2.position.z = 40;
cube2.position.y = 0;
cube2.scale.set(300, 1, 300);
scene.add(cube2)

const cube3 = new THREE.Mesh(geometry, material);
cube3.position.z = 20;
cube3.position.y = 5;
cube3.scale.set(10, 10, 10);
scene.add(cube3)

const cube4 = new THREE.Mesh(geometry, material3);
cube4.position.z = 20;
cube4.position.x= 20;
cube4.position.y= 5;
cube4.scale.set(10, 10, 10);
scene.add(cube4)

// Adicionar luz
const hemisphereLight = new THREE.HemisphereLight(0xFFFFFF, 0x000000, 0.6);
hemisphereLight.position.set(10, -2, 10);
scene.add(hemisphereLight);

// Controles
const controls = new THREE.OrbitControls(camera, renderer.domElement);
controls.enableDamping = true;
controls.dampingFactor = 0.3;

// Configuração do ray tracing (myCanvas2)
const canvas2D = document.getElementById('myCanvas2');
const ctx = canvas2D.getContext('2d');

// Ajustar tamanho do canvas 2D para match com CSS
function resizeCanvas2D() {
const displayWidth = canvas2D.clientWidth;
const displayHeight = canvas2D.clientHeight;

if (canvas2D.width !== displayWidth || canvas2D.height !== displayHeight) {
    canvas2D.width = displayWidth;
    canvas2D.height = displayHeight;
}

}

// Configurações do ray tracer
const samplesPerPixel = 100;
const maxDepth = 5;
const tileSize = 40;
const microTileSize = 20;
let currentTileX = 0;
let currentTileY = 0;
let currentMicroTileX = 0;
let currentMicroTileY = 0;
let tilesX = 0;
let tilesY = 0;
let microTilesX = 0;
let microTilesY = 0;
let renderStartTime = null;
let finalImage = null;

// Classe Vec3 adaptada para trabalhar com THREE.Vector3
class Vec3 {
constructor(x, y, z) {
this.x = x || 0;
this.y = y || 0;
this.z = z || 0;
}

static fromThreeVector(v) {
    return new Vec3(v.x, v.y, v.z);
}

toThreeVector() {
    return new THREE.Vector3(this.x, this.y, this.z);
}

add(v) { return new Vec3(this.x + v.x, this.y + v.y, this.z + v.z); }
sub(v) { return new Vec3(this.x - v.x, this.y - v.y, this.z - v.z); }
mul(s) { return new Vec3(this.x * s, this.y * s, this.z * s); }
div(s) { return new Vec3(this.x / s, this.y / s, this.z / s); }
dot(v) { return this.x * v.x + this.y * v.y + this.z * v.z; }
cross(v) { 
    return new Vec3(
        this.y * v.z - this.z * v.y,
        this.z * v.x - this.x * v.z,
        this.x * v.y - this.y * v.x
    );
}
length() { return Math.sqrt(this.dot(this)); }
normalize() { 
    const len = this.length();
    return len > 0 ? this.div(len) : new Vec3();
}
reflect(normal) {
    return this.sub(normal.mul(2 * this.dot(normal)));
}

}

// Classe Material
class Material {
constructor(color, emission = 0, reflectivity = 0) {
this.color = color;
this.emission = emission;
this.reflectivity = reflectivity;
}
}

// Classe Sphere adaptada para Three.js
class Sphere {
constructor(center, radius, material) {
this.center = center;
this.radius = radius;
this.material = material;
}

hit(ray, tMin, tMax) {
    const oc = ray.origin.sub(this.center);
    const a = ray.direction.dot(ray.direction);
    const b = oc.dot(ray.direction);
    const c = oc.dot(oc) - this.radius * this.radius;
    const discriminant = b * b - a * c;

    if (discriminant > 0) {
        const temp = (-b - Math.sqrt(discriminant)) / a;
        if (temp < tMax && temp > tMin) {
            const point = ray.origin.add(ray.direction.mul(temp));
            const normal = point.sub(this.center).div(this.radius);
            return {
                t: temp,
                point: point,
                normal: normal,
                material: this.material
            };
        }

        const temp2 = (-b + Math.sqrt(discriminant)) / a;
        if (temp2 < tMax && temp2 > tMin) {
            const point = ray.origin.add(ray.direction.mul(temp2));
            const normal = point.sub(this.center).div(this.radius);
            return {
                t: temp2,
                point: point,
                normal: normal,
                material: this.material
            };
        }
    }
    return null;
}

}

// Classe Plane adaptada para Three.js
class Plane {
constructor(position, normal, material) {
this.position = position;
this.normal = normal;
this.material = material;
}

hit(ray, tMin, tMax) {
    const denom = this.normal.dot(ray.direction);
    if (Math.abs(denom) > 0.0001) {
        const t = this.position.sub(ray.origin).dot(this.normal) / denom;
        if (t >= tMin && t <= tMax) {
            const point = ray.origin.add(ray.direction.mul(t));
            return {
                t: t,
                point: point,
                normal: this.normal,
                material: this.material
            };
        }
    }
    return null;
}

}

// Classe Box adaptada para Three.js
class Box {
constructor(position, size, material) {
this.position = position;
this.size = size;
this.material = material;
this.min = position.sub(size.mul(0.5));
this.max = position.add(size.mul(0.5));
}

hit(ray, tMin, tMax) {
    let tmin = (this.min.x - ray.origin.x) / ray.direction.x;
    let tmax = (this.max.x - ray.origin.x) / ray.direction.x;

    if (tmin > tmax) [tmin, tmax] = [tmax, tmin];

    let tymin = (this.min.y - ray.origin.y) / ray.direction.y;
    let tymax = (this.max.y - ray.origin.y) / ray.direction.y;

    if (tymin > tymax) [tymin, tymax] = [tymax, tymin];

    if ((tmin > tymax) || (tymin > tmax)) return null;

    if (tymin > tmin) tmin = tymin;
    if (tymax < tmax) tmax = tymax;

    let tzmin = (this.min.z - ray.origin.z) / ray.direction.z;
    let tzmax = (this.max.z - ray.origin.z) / ray.direction.z;

    if (tzmin > tzmax) [tzmin, tzmax] = [tzmax, tzmin];

    if ((tmin > tzmax) || (tzmin > tmax)) return null;

    if (tzmin > tmin) tmin = tzmin;
    if (tzmax < tmax) tmax = tzmax;

    if (tmin > tMin && tmin < tMax) {
        const point = ray.origin.add(ray.direction.mul(tmin));
        let normal = new Vec3(0, 0, 0);
        
        if (Math.abs(point.x - this.min.x) < 0.0001) normal = new Vec3(-1, 0, 0);
        else if (Math.abs(point.x - this.max.x) < 0.0001) normal = new Vec3(1, 0, 0);
        else if (Math.abs(point.y - this.min.y) < 0.0001) normal = new Vec3(0, -1, 0);
        else if (Math.abs(point.y - this.max.y) < 0.0001) normal = new Vec3(0, 1, 0);
        else if (Math.abs(point.z - this.min.z) < 0.0001) normal = new Vec3(0, 0, -1);
        else if (Math.abs(point.z - this.max.z) < 0.0001) normal = new Vec3(0, 0, 1);

        return {
            t: tmin,
            point: point,
            normal: normal,
            material: this.material
        };
    }

    return null;
}

}

// Classe Ray
class Ray {
constructor(origin, direction) {
this.origin = origin;
this.direction = direction;
}
}

// Função para converter cena Three.js para objetos do ray tracer
function convertSceneToRT() {
const rtObjects = [];

scene.children.forEach(child => {
    if (child instanceof THREE.Mesh && child !== gridHelper) {
        const position = Vec3.fromThreeVector(child.position);
        const scale = Vec3.fromThreeVector(child.scale);
        const color = child.material.color.getHex();
        
        if (child.geometry.type.includes('Sphere')) {
            const radius = scale.x; // Assumindo escala uniforme
            const material = new Material({
                r: (color >> 16) & 255,
                g: (color >> 8) & 255,
                b: color & 255
            }, 0, 0.1);
            
            rtObjects.push(new Sphere(position, radius, material));
        }
        else if (child.geometry.type.includes('Box')) {
            const material = new Material({
                r: (color >> 16) & 255,
                g: (color >> 8) & 255,
                b: color & 255
            }, 0, 0.05);
            
            rtObjects.push(new Box(position, scale, material));
        }
        else if (child.geometry.type.includes('Plane')) {
            const normal = new Vec3(0, 1, 0); // Plano horizontal
            const material = new Material({
                r: (color >> 16) & 255,
                g: (color >> 8) & 255,
                b: color & 255
            }, 0, 0.0);
            
            rtObjects.push(new Plane(position, normal, material));
        }
    }
});

return rtObjects;

}

// Função para converter luzes Three.js
function convertLightsToRT() {
const rtLights = [];

scene.children.forEach(child => {
    if (child instanceof THREE.Light) {
        rtLights.push({
            position: Vec3.fromThreeVector(child.position),
            color: {
                r: (child.color.getHex() >> 16) & 255,
                g: (child.color.getHex() >> 8) & 255,
                b: child.color.getHex() & 255
            },
            intensity: child.intensity
        });
    }
});

return rtLights;

}

// Variáveis globais para a cena RT
let rtObjects = [];
let rtLights = [];
let rtCamera = null;

function randomInHemisphere(normal) {
const inUnitSphere = new Vec3(
Math.random() * 2 - 1,
Math.random() * 2 - 1,
Math.random() * 2 - 1
).normalize();
return inUnitSphere.dot(normal) > 0 ? inUnitSphere : inUnitSphere.mul(-1);
}

function traceRay(ray, depth = 0) {
if (depth > maxDepth) return {r: 0, g: 0, b: 0};

// Encontrar o objeto mais próximo atingido pelo raio
let closestHit = null;
let closestDist = Infinity;

for (const obj of rtObjects) {
    const hit = obj.hit(ray, 0.001, Infinity);
    if (hit && hit.t < closestDist) {
        closestDist = hit.t;
        closestHit = hit;
    }
}

if (!closestHit) {
    // Cor do céu/fundo
    const t = 0.5 * (ray.direction.y + 1.0);
    return {
        r: (0.5 + 0.3 * t) * 255,
        g: (0.7 + 0.3 * t) * 255,
        b: (1.0 + 0.0 * t) * 255
    };
}

const material = closestHit.material;

// Emissão de luz
if (material.emission > 0) {
    return {
        r: material.color.r * material.emission,
        g: material.color.g * material.emission,
        b: material.color.b * material.emission
    };
}

// Reflexão difusa
const target = closestHit.point.add(closestHit.normal).add(randomInHemisphere(closestHit.normal));
const diffuseRay = new Ray(closestHit.point, target.sub(closestHit.point).normalize());
const diffuseColor = traceRay(diffuseRay, depth + 1);

// Reflexão especular
let specularColor = {r: 0, g: 0, b: 0};
if (material.reflectivity > 0) {
    const reflected = ray.direction.reflect(closestHit.normal);
    const reflectionRay = new Ray(closestHit.point, reflected);
    specularColor = traceRay(reflectionRay, depth + 1);
}

// Combinar cores
const diffuseAmount = 0.7 * (1 - material.reflectivity);
const specularAmount = 0.3 * material.reflectivity;

return {
    r: (diffuseColor.r * diffuseAmount + specularColor.r * specularAmount) * material.color.r / 255,
    g: (diffuseColor.g * diffuseAmount + specularColor.g * specularAmount) * material.color.g / 255,
    b: (diffuseColor.b * diffuseAmount + specularColor.b * specularAmount) * material.color.b / 255
};

}

// Inicializar buffer de imagem
function initImageBuffer() {
resizeCanvas2D();
finalImage = ctx.createImageData(canvas2D.width, canvas2D.height);
for (let i = 0; i < finalImage.data.length; i += 4) {
finalImage.data[i] = 0;
finalImage.data[i + 1] = 0;
finalImage.data[i + 2] = 0;
finalImage.data[i + 3] = 255;
}
renderStartTime = performance.now();

// Calcular tiles
tilesX = Math.ceil(canvas2D.width / tileSize);
tilesY = Math.ceil(canvas2D.height / tileSize);
microTilesX = Math.ceil(tileSize / microTileSize);
microTilesY = Math.ceil(tileSize / microTileSize);

currentTileX = 0;
currentTileY = 0;
currentMicroTileX = 0;
currentMicroTileY = 0;

}

// Atualizar status
function updateStatus() {
const elapsed = ((performance.now() - renderStartTime) / 1000).toFixed(1);
const totalTiles = tilesX * tilesY * microTilesX * microTilesY;
const tilesCompleted =
(currentTileY * tilesX + currentTileX) * (microTilesX * microTilesY) +
(currentMicroTileY * microTilesX + currentMicroTileX);
const progress = ((tilesCompleted / totalTiles) * 100).toFixed(1);
console.log(Renderizando: ${progress}% | Tempo: ${elapsed}s);
}

// Renderizar um micro tile
function renderMicroTile() {
const data = finalImage.data;
const width = canvas2D.width;
const height = canvas2D.height;

const tileStartX = currentTileX * tileSize;
const tileStartY = currentTileY * tileSize;
const microStartX = tileStartX + currentMicroTileX * microTileSize;
const microStartY = tileStartY + currentMicroTileY * microTileSize;
const microEndX = Math.min(microStartX + microTileSize, tileStartX + tileSize, width);
const microEndY = Math.min(microStartY + microTileSize, tileStartY + tileSize, height);

const aspectRatio = width / height;
const cameraPos = Vec3.fromThreeVector(camera.position);

for (let y = microStartY; y < microEndY; y++) {
    for (let x = microStartX; x < microEndX; x++) {
        let pixelColor = {r: 0, g: 0, b: 0};
        
        for (let s = 0; s < samplesPerPixel; s++) {
            const u = (x + Math.random()) / width;
            const v = (y + Math.random()) / height;
            
            const rayDir = new Vec3(
                aspectRatio * (2.0 * u - 1.0),
                1.0 - 2.0 * v,
                -1.0
            ).normalize();
            
            // Converter para coordenadas do mundo usando a rotação da câmera
            const threeDir = new THREE.Vector3(rayDir.x, rayDir.y, rayDir.z);
            threeDir.applyEuler(camera.rotation);
            
            const worldRayDir = Vec3.fromThreeVector(threeDir);
            const sampleColor = traceRay(new Ray(cameraPos, worldRayDir));
            
            pixelColor.r += sampleColor.r;
            pixelColor.g += sampleColor.g;
            pixelColor.b += sampleColor.b;
        }
        
        // Média das amostras
        pixelColor.r /= samplesPerPixel;
        pixelColor.g /= samplesPerPixel;
        pixelColor.b /= samplesPerPixel;
        
        // Correção gamma
        pixelColor.r = Math.sqrt(pixelColor.r / 255) * 255;
        pixelColor.g = Math.sqrt(pixelColor.g / 255) * 255;
        pixelColor.b = Math.sqrt(pixelColor.b / 255) * 255;
        
        const idx = (y * width + x) * 4;
        data[idx] = Math.floor(pixelColor.r);
        data[idx + 1] = Math.floor(pixelColor.g);
        data[idx + 2] = Math.floor(pixelColor.b);
    }
}

ctx.putImageData(finalImage, 0, 0);

// Avançar para o próximo micro tile
currentMicroTileX++;
if (currentMicroTileX >= microTilesX) {
    currentMicroTileX = 0;
    currentMicroTileY++;
    
    if (currentMicroTileY >= microTilesY) {
        currentMicroTileY = 0;
        currentTileX++;
        
        if (currentTileX >= tilesX) {
            currentTileX = 0;
            currentTileY++;
        }
    }
}

updateStatus();

// Continuar renderizando ou finalizar
if (currentTileY < tilesY) {
    setTimeout(renderMicroTile, 0);
} else {
    const totalTime = ((performance.now() - renderStartTime) / 1000).toFixed(1);
    console.log(`Renderização completa em ${totalTime}s`);
}

}

// Iniciar renderização
function startRendering() {
// Converter cena Three.js para ray tracing
rtObjects = convertSceneToRT();
rtLights = convertLightsToRT();

// Limpar canvas
ctx.fillStyle = '#1E1E1E';
ctx.fillRect(0, 0, canvas2D.width, canvas2D.height);

// Iniciar renderização
initImageBuffer();
renderMicroTile();

}

// Evento do botão render
document.getElementById('render').addEventListener('click', startRendering);

// Redimensionamento
window.addEventListener('resize', function() {
renderer.setSize(window.innerWidth, window.innerHeight);
camera.aspect = window.innerWidth / window.innerHeight;
camera.updateProjectionMatrix();
});

// Loop de animação Three.js
function animate() {
requestAnimationFrame(animate);
controls.update();
renderer.render(scene, camera);
}
animate();

Desculpa a confusão no código, não sei usar bem o GitHub 😅😅

[Nandazdev]

[Nandazdev]

[Nandazdev2]

[Nandazdev2]

@erichlof muito obrigado pela motivação e pelas dicas