fix(tools/shadertoy): sync templates and script to current codebase conventions

- template.h/cc: new Effect constructor/render signatures, RAII wrappers,
  HEADLESS_RETURN_IF_NULL, #pragma once
- template.wgsl: sequence_uniforms + render/fullscreen_uv_vs includes,
  UniformsSequenceParams at binding 2, VertexOutput in fs_main
- convert_shadertoy.py: paths src/effects/ + src/shaders/, new Effect
  pattern (create_post_process_pipeline, pp_update_bind_group), correct
  field names (beat_time/beat_phase), updated next-steps instructions
- README.md: streamlined to quick-ref; accurate GLSL→WGSL table and uniforms

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

1 files changed, 33 insertions, 42 deletions

diff --git a/tools/shadertoy/template.wgsl b/tools/shadertoy/template.wgsl
index 37e7def..573fa97 100644
--- a/tools/shadertoy/template.wgsl
+++ b/tools/shadertoy/template.wgsl
@@ -1,32 +1,14 @@
 // 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 "sequence_uniforms"
+#include "render/fullscreen_uv_vs"  // <- VertexOutput + vs_main
 
-#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);
-}
+// Scene effect: only uniforms (bindings 0,1 unused)
+// For post-process (input texture needed), add:
+//   @group(0) @binding(0) var smplr: sampler;
+//   @group(0) @binding(1) var txt: texture_2d<f32>;
+@group(0) @binding(2) var<uniform> uniforms: UniformsSequenceParams;
 
 // ============================================================================
 // PASTE SHADERTOY CODE HERE
@@ -36,55 +18,64 @@ struct ShaderToyParams {
 // 1. Replace ShaderToy uniforms:
 //    iResolution.xy        → uniforms.resolution
 //    iTime                 → uniforms.time
-//    fragCoord             → p.xy (from @builtin(position))
+//    fragCoord             → in.position.xy (pixel coords) or in.uv * uniforms.resolution
 //    fragColor             → return value
 //
 // 2. Coordinate conversion:
 //    vec2 uv = fragCoord / iResolution.xy;
 //    becomes:
-//    let uv = p.xy / uniforms.resolution;
+//    let uv = in.uv;  // [0..1], origin top-left
+//    // OR for ShaderToy convention (origin bottom-left):
+//    let uv = vec2f(in.uv.x, 1.0 - in.uv.y);
 //
 // 3. Type syntax changes:
 //    float                 → f32
-//    vec2/vec3/vec4        → vec2<f32>, vec3<f32>, vec4<f32>
-//    mat2/mat3/mat4        → mat2x2<f32>, mat3x3<f32>, mat4x4<f32>
+//    vec2/vec3/vec4        → vec2f, vec3f, vec4f
+//    mat2/mat3/mat4        → mat2x2f, mat3x3f, mat4x4f
 //
 // 4. Function syntax:
-//    float foo(vec2 p)     → fn foo(p: vec2<f32>) -> f32
+//    float foo(vec2 p)     → fn foo(p: vec2f) -> 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)
+//    mix, sin, cos, length, normalize, dot, cross, fract(), etc.
+//    mod(x, y)             → x % y
 //
-// 6. Texture sampling:
+// 6. Texture sampling (requires bindings 0,1 in C++ and shader):
 //    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.
+// 8. Beat / audio:
+//    uniforms.beat_time    → absolute musical beats
+//    uniforms.beat_phase   → fractional beat [0..1]
+//    uniforms.audio_intensity → audio reactivity
 //
 // ============================================================================
 
-@fragment fn fs_main(@builtin(position) p: vec4<f32>) -> @location(0) vec4<f32> {
+@fragment fn fs_main(in: VertexOutput) -> @location(0) vec4f {
     // TODO: Paste and adapt ShaderToy mainImage() body here
 
-    // Example coordinate setup (typical ShaderToy pattern):
-    let uv = p.xy / uniforms.resolution;
+    // Standard UV (origin top-left, [0..1])
+    let uv = in.uv;
+
+    // For ShaderToy convention (origin bottom-left, [-1..1] centered):
+    // let q = vec2f(in.uv.x, 1.0 - in.uv.y);
+    // var coord = q * 2.0 - 1.0;
+    // coord.x *= uniforms.aspect_ratio;
 
     // TODO: Your effect code here
-    var col = vec3<f32>(uv.x, uv.y, 0.5);
+    var col = vec3f(uv.x, uv.y, 0.5);
 
-    // Optional: Sample previous frame
+    // Optional: Sample previous frame (requires bindings 0,1)
     // 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;
+    // col *= 1.0 + uniforms.beat_phase * 0.1;
 
-    return vec4<f32>(col, 1.0);
+    return vec4f(col, 1.0);
 }