feat: Add ShaderToy conversion tools

Add automated conversion pipeline for ShaderToy shaders to demo effects:
- convert_shadertoy.py: Automated code generation script
- Manual templates: Header, implementation, and WGSL boilerplate
- Example shader: Test case for conversion workflow
- README: Complete conversion guide with examples

Handles basic GLSL→WGSL conversion (types, uniforms, mainImage extraction).
Manual fixes needed for fragColor returns and complex type inference.

Organized under tools/shadertoy/ for maintainability.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

1 files changed, 90 insertions, 0 deletions

diff --git a/tools/shadertoy/template.wgsl b/tools/shadertoy/template.wgsl
new file mode 100644
index 0000000..37e7def
--- /dev/null
+++ b/tools/shadertoy/template.wgsl
@@ -0,0 +1,90 @@
+// ShaderToy conversion template for 64k demo project
+// TODO: Paste ShaderToy mainImage() function below and adapt
+
+@group(0) @binding(0) var smplr: sampler;
+@group(0) @binding(1) var txt: texture_2d<f32>;
+
+#include "common_uniforms"
+
+@group(0) @binding(2) var<uniform> uniforms: CommonUniforms;
+
+// TODO: Define your effect parameters (must match C++ struct)
+struct ShaderToyParams {
+    param1: f32,
+    param2: f32,
+    _pad0: f32,
+    _pad1: f32,
+}
+
+@group(0) @binding(3) var<uniform> params: ShaderToyParams;
+
+// Standard fullscreen triangle vertex shader
+@vertex fn vs_main(@builtin(vertex_index) i: u32) -> @builtin(position) vec4<f32> {
+    var pos = array<vec2<f32>, 3>(
+        vec2<f32>(-1.0, -1.0),
+        vec2<f32>(3.0, -1.0),
+        vec2<f32>(-1.0, 3.0)
+    );
+    return vec4<f32>(pos[i], 0.0, 1.0);
+}
+
+// ============================================================================
+// PASTE SHADERTOY CODE HERE
+// ============================================================================
+// ShaderToy → WGSL conversion notes:
+//
+// 1. Replace ShaderToy uniforms:
+//    iResolution.xy        → uniforms.resolution
+//    iTime                 → uniforms.time
+//    fragCoord             → p.xy (from @builtin(position))
+//    fragColor             → return value
+//
+// 2. Coordinate conversion:
+//    vec2 uv = fragCoord / iResolution.xy;
+//    becomes:
+//    let uv = p.xy / uniforms.resolution;
+//
+// 3. Type syntax changes:
+//    float                 → f32
+//    vec2/vec3/vec4        → vec2<f32>, vec3<f32>, vec4<f32>
+//    mat2/mat3/mat4        → mat2x2<f32>, mat3x3<f32>, mat4x4<f32>
+//
+// 4. Function syntax:
+//    float foo(vec2 p)     → fn foo(p: vec2<f32>) -> f32
+//
+// 5. Common functions (mostly same):
+//    mix, sin, cos, length, normalize, dot, cross, etc.
+//    fract()               → fract()
+//    mod(x, y)             → x % y  OR  x - y * floor(x / y)
+//
+// 6. Texture sampling:
+//    texture(iChannel0, uv) → textureSample(txt, smplr, uv)
+//
+// 7. Variable declarations:
+//    float x = 1.0;        → var x: f32 = 1.0;  OR  let x = 1.0;
+//    const float x = 1.0;  → const x: f32 = 1.0;
+//
+// 8. Swizzling is the same: col.rgb, uv.xy, etc.
+//
+// ============================================================================
+
+@fragment fn fs_main(@builtin(position) p: vec4<f32>) -> @location(0) vec4<f32> {
+    // TODO: Paste and adapt ShaderToy mainImage() body here
+
+    // Example coordinate setup (typical ShaderToy pattern):
+    let uv = p.xy / uniforms.resolution;
+
+    // TODO: Your effect code here
+    var col = vec3<f32>(uv.x, uv.y, 0.5);
+
+    // Optional: Sample previous frame
+    // var prev_col = textureSample(txt, smplr, uv);
+
+    // Optional: Audio reactivity
+    // col *= 1.0 + uniforms.audio_intensity * 0.2;
+
+    // Optional: Beat sync
+    // col *= 1.0 + uniforms.beat * 0.1;
+
+    return vec4<f32>(col, 1.0);
+}