Geometry Shader Explosion

Overview

An interactive OpenGL demonstration of real-time 3D model explosion effects achieved using a geometry shader. The shader subdivides each triangle of the model into smaller ones, creating hundreds of individual primitives that scatter throughout 3D space. The simulation is highly customizable, with many effects that can be used to achieve the desired effect.

Demo

demo1.mp4

demo2.mp4

Installation

This project uses uv - dependencies are pinned in uv.lock.

Install dependencies:

uv sync

Run the application:

uv run python src/main.py

Controls

Key	Action
W/S/A/D	Move camera
Mouse	Look around
ESC	Quit
UI panel	Adjust explosion parameters

Configuration

All program parameters can be customized in config.toml at the project root. This includes window settings, initial camera position, default explosion values and model paths.

For example, to set up the window, adjust these options:

[window]
title = "Geometry Shader Explosion"
size = [1600, 1000]
fps = 60

Explosion Parameters

Many of the parameters defined initially in config.toml can be adjusted dynamically while the program is running. Some changes require resetting the simulation to take effect.

Available parameters control the following aspects of the simulation:

• 3D Model - OBJ file used as source mesh for the explosion (ensure the file format is specified correctly; for examples, see config.toml)
• Time Multiplier - simulation speed; values greater than 1.0 accelerate time while negative values play the simulation in reverse
• Explosion Origin - XYZ coordinates in world space defining explosion origin
• Magnitude - initial explosion force
• Falloff Radius - maximum distance affected by explosion
• Falloff Strength - exponent controlling how quickly force decreases with distance
• Random Strength - strength of random direction scatter
• Impulse Decay - exponent defining how momentum changes over time
• Gravity Power - downward acceleration applied to all primitives

To better understand how each parameter affects the explosion, see the geometry shader logic:

float falloff(float len) {
    return pow(clamp(1.0 - len / falloff_radius, 0.0, 1.0), falloff_strength);
}

float impulse() {
    return pow(time, impulse_decay) * magnitude;
}

vec3 gravity() {
    return vec3(0, -1, 0) * gravity_power * time * time;
}

vec3 explode(vec3 pos) {
    vec3 dir = surface_center() - explosion_origin;
    float dist = length(dir);
    dir = normalize(dir);
    return pos + randomise_vec(dir) * impulse() * falloff(dist) + gravity();
}