Add shader presets (CRT/Scanlines) and a functional screenshot hotkey

CMakeLists.txt

@@ -309,3 +309,12 @@ target_sources(SuperMetroidSNESRecomp PRIVATE
 target_include_directories(SuperMetroidSNESRecomp PRIVATE
     ${SNESRECOMP_ROOT}/host
     ${RECOMP_UI_ROOT}/src)
+
+# GLSL shader presets (CRT/scanlines) for the OpenGL desktop backend. The
+# launcher's shader dropdown scans assets/shaders beside the executable for
+# *.glsl/*.glslp; src/main.c opts this game into that row.
+if(NOT ANDROID)
+    snesrecomp_target_stage_dir(SuperMetroidSNESRecomp
+        ${CMAKE_CURRENT_SOURCE_DIR}/assets/shaders
+        assets/shaders)
+endif()

assets/shaders/.src/crt.glsl

@@ -0,0 +1,57 @@
+// Lightweight CRT look: scanlines + a coarse RGB aperture-grille mask +
+// a soft vignette. Deliberately no curvature/distortion -- keeps every
+// output pixel address identical to the input, so it stays cheap and safe
+// (no sampling outside [0,1], no divide-by-zero). Single pass; see
+// scanlines.glsl for the preset-format notes.
+
+#if defined(VERTEX)
+
+in vec2 VertexCoord;
+in vec2 TexCoord;
+out vec2 vTexCoord;
+uniform mat4 MVPMatrix;
+
+void main() {
+  gl_Position = MVPMatrix * vec4(VertexCoord, 0.0, 1.0);
+  vTexCoord = TexCoord;
+}
+
+#elif defined(FRAGMENT)
+
+#pragma parameter CRT_SCANLINE_STRENGTH "CRT Scanline Strength" 0.78 0.0 1.0 0.02
+#pragma parameter CRT_MASK_STRENGTH "CRT Mask Strength" 0.25 0.0 1.0 0.05
+#pragma parameter CRT_VIGNETTE_STRENGTH "CRT Vignette Strength" 0.35 0.0 1.0 0.05
+
+in vec2 vTexCoord;
+out vec4 FragColor;
+
+uniform sampler2D Texture;
+uniform float CRT_SCANLINE_STRENGTH;
+uniform float CRT_MASK_STRENGTH;
+uniform float CRT_VIGNETTE_STRENGTH;
+
+void main() {
+  vec4 color = texture(Texture, vTexCoord);
+
+  // One dark output row in every two.
+  float row = floor(gl_FragCoord.y);
+  float scan = mix(1.0, CRT_SCANLINE_STRENGTH, mod(row, 2.0));
+
+  // Coarse RGB aperture-grille mask across output columns.
+  float col = mod(floor(gl_FragCoord.x), 3.0);
+  vec3 mask;
+  if (col < 1.0)
+    mask = vec3(1.0, 1.0 - CRT_MASK_STRENGTH, 1.0 - CRT_MASK_STRENGTH);
+  else if (col < 2.0)
+    mask = vec3(1.0 - CRT_MASK_STRENGTH, 1.0, 1.0 - CRT_MASK_STRENGTH);
+  else
+    mask = vec3(1.0 - CRT_MASK_STRENGTH, 1.0 - CRT_MASK_STRENGTH, 1.0);
+
+  // Soft vignette toward the edges.
+  vec2 uv = vTexCoord * 2.0 - 1.0;
+  float vig = 1.0 - CRT_VIGNETTE_STRENGTH * dot(uv, uv) * 0.5;
+
+  FragColor = vec4(color.rgb * scan * mask * vig, color.a);
+}
+
+#endif

assets/shaders/.src/scanlines.glsl

@@ -0,0 +1,38 @@
+// Simple horizontal-scanline preset. Single pass; see glsl_shader.c for the
+// preset/parameter parser this file is compiled against (GLSL 330 core --
+// the profile src/opengl.c already requires via
+// SDL_GL_CONTEXT_PROFILE_CORE). No #version line: the loader prepends
+// "#version 330\n" (core, since no profile qualifier defaults to core).
+
+#if defined(VERTEX)
+
+in vec2 VertexCoord;
+in vec2 TexCoord;
+out vec2 vTexCoord;
+uniform mat4 MVPMatrix;
+
+void main() {
+  gl_Position = MVPMatrix * vec4(VertexCoord, 0.0, 1.0);
+  vTexCoord = TexCoord;
+}
+
+#elif defined(FRAGMENT)
+
+#pragma parameter SCANLINE_STRENGTH "Scanline Strength" 0.72 0.0 1.0 0.02
+#pragma parameter SCANLINE_WIDTH "Scanline Width (px)" 2.0 1.0 4.0 1.0
+
+in vec2 vTexCoord;
+out vec4 FragColor;
+
+uniform sampler2D Texture;
+uniform float SCANLINE_STRENGTH;
+uniform float SCANLINE_WIDTH;
+
+void main() {
+  vec4 color = texture(Texture, vTexCoord);
+  float row = floor(gl_FragCoord.y / SCANLINE_WIDTH);
+  float dark = mix(1.0, SCANLINE_STRENGTH, mod(row, 2.0));
+  FragColor = vec4(color.rgb * dark, color.a);
+}
+
+#endif

assets/shaders/crt-light.glslp

@@ -0,0 +1,7 @@
+shaders = "1"
+shader0 = ".src/crt.glsl"
+filter_linear0 = "false"
+parameters = "CRT_SCANLINE_STRENGTH;CRT_MASK_STRENGTH;CRT_VIGNETTE_STRENGTH"
+CRT_SCANLINE_STRENGTH = "0.88"
+CRT_MASK_STRENGTH = "0.12"
+CRT_VIGNETTE_STRENGTH = "0.18"

assets/shaders/crt-strong.glslp

@@ -0,0 +1,7 @@
+shaders = "1"
+shader0 = ".src/crt.glsl"
+filter_linear0 = "false"
+parameters = "CRT_SCANLINE_STRENGTH;CRT_MASK_STRENGTH;CRT_VIGNETTE_STRENGTH"
+CRT_SCANLINE_STRENGTH = "0.60"
+CRT_MASK_STRENGTH = "0.40"
+CRT_VIGNETTE_STRENGTH = "0.55"

assets/shaders/crt.glslp

@@ -0,0 +1,3 @@
+shaders = "1"
+shader0 = ".src/crt.glsl"
+filter_linear0 = "false"

assets/shaders/scanlines-light.glslp

@@ -0,0 +1,6 @@
+shaders = "1"
+shader0 = ".src/scanlines.glsl"
+filter_linear0 = "false"
+parameters = "SCANLINE_STRENGTH;SCANLINE_WIDTH"
+SCANLINE_STRENGTH = "0.85"
+SCANLINE_WIDTH = "2.0"

assets/shaders/scanlines-strong.glslp

@@ -0,0 +1,6 @@
+shaders = "1"
+shader0 = ".src/scanlines.glsl"
+filter_linear0 = "false"
+parameters = "SCANLINE_STRENGTH;SCANLINE_WIDTH"
+SCANLINE_STRENGTH = "0.55"
+SCANLINE_WIDTH = "2.0"

assets/shaders/scanlines.glslp

@@ -0,0 +1,3 @@
+shaders = "1"
+shader0 = ".src/scanlines.glsl"
+filter_linear0 = "false"

config.ini

@@ -25,6 +25,8 @@ VSync = 1
 # presets), software, or an SDL render driver such as vulkan. Empty follows
 # OutputMethod.
 Renderer = auto
+# OpenGL GLSL preset path, edited by the launcher's shader dropdown.
+Shader =
 WindowSize = Auto
 Fullscreen = 0
 WindowScale = 3
@@ -62,7 +64,9 @@ Save = Shift+F1,Shift+F2,Shift+F3,Shift+F4,Shift+F5,Shift+F6,Shift+F7,Shift+F8,S
 # In-game overlays (framework modules). The save-state browser also opens
 # with Select+R on the pad; rewind with [Controller] RewindGesture below.
 SaveStateMenu = F11
-Rewind = F12
+Rewind = Shift+F12
+# OpenGL framebuffer capture, saved under screenshots/.
+Screenshot = F12
 
 [GamepadMap]
 EnableGamepad1 = true

src/main.c

@@ -218,6 +218,7 @@ static const SnesDesktopHostGame kSuperMetroidHost = {
   .debug_port = 4380,
   .widescreen_supported = 0,       /* widescreen is this title's Mods page */
   .msu1_supported = 0,
+  .shader_supported = 1,
   .simulation_hz = SM_SIMULATION_HZ,
   .frame_width = 256,
   .frame_height = SM_HEIGHT,