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, 120 insertions, 0 deletions

diff --git a/tools/shadertoy/template.cc b/tools/shadertoy/template.cc
new file mode 100644
index 0000000..288283d
--- /dev/null
+++ b/tools/shadertoy/template.cc
@@ -0,0 +1,120 @@
+// This file is part of the 64k demo project.
+// ShaderToy effect implementation - REPLACE THIS LINE
+// TODO: Update description, rename class
+
+#include "gpu/effects/shadertoy_effect.h"
+#include "gpu/effects/shader_composer.h"
+#include "generated/assets.h"
+
+// TODO: Rename class and adjust constructor parameters
+ShaderToyEffect::ShaderToyEffect(const GpuContext& ctx) : Effect(ctx) {
+}
+
+ShaderToyEffect::~ShaderToyEffect() {
+  if (sampler_)
+    wgpuSamplerRelease(sampler_);
+  if (bind_group_)
+    wgpuBindGroupRelease(bind_group_);
+  if (pipeline_)
+    wgpuRenderPipelineRelease(pipeline_);
+}
+
+void ShaderToyEffect::init(MainSequence* demo) {
+  demo_ = demo;
+  params_.init(ctx_.device);
+
+  WGPUSamplerDescriptor sampler_desc = {};
+  sampler_desc.addressModeU = WGPUAddressMode_ClampToEdge;
+  sampler_desc.addressModeV = WGPUAddressMode_ClampToEdge;
+  sampler_desc.magFilter = WGPUFilterMode_Linear;
+  sampler_desc.minFilter = WGPUFilterMode_Linear;
+  sampler_desc.mipmapFilter = WGPUMipmapFilterMode_Linear;
+  sampler_desc.maxAnisotropy = 1;
+  sampler_ = wgpuDeviceCreateSampler(ctx_.device, &sampler_desc);
+
+  // TODO: Update asset name to match your shader file
+  size_t shader_size;
+  const char* shader_code = (const char*)GetAsset(
+      AssetId::ASSET_SHADERTOY_SHADER, &shader_size);
+
+  std::string composed = ShaderComposer::Get().Compose({}, shader_code);
+
+  WGPUShaderSourceWGSL wgsl = {};
+  wgsl.chain.sType = WGPUSType_ShaderSourceWGSL;
+  wgsl.code = str_view(composed.c_str());
+
+  WGPUShaderModuleDescriptor desc = {};
+  desc.nextInChain = &wgsl.chain;
+  WGPUShaderModule module = wgpuDeviceCreateShaderModule(ctx_.device, &desc);
+
+  const WGPUColorTargetState target = {
+      .format = ctx_.format,
+      .writeMask = WGPUColorWriteMask_All,
+  };
+  WGPUFragmentState frag = {};
+  frag.module = module;
+  frag.entryPoint = str_view("fs_main");
+  frag.targetCount = 1;
+  frag.targets = ⌖
+
+  const WGPUDepthStencilState depth_stencil = {
+      .format = WGPUTextureFormat_Depth24Plus,
+      .depthWriteEnabled = WGPUOptionalBool_False,
+      .depthCompare = WGPUCompareFunction_Always,
+  };
+
+  WGPURenderPipelineDescriptor pipeline_desc = {};
+  pipeline_desc.label = label_view("ShaderToyEffect");
+  pipeline_desc.vertex.module = module;
+  pipeline_desc.vertex.entryPoint = str_view("vs_main");
+  pipeline_desc.primitive.topology = WGPUPrimitiveTopology_TriangleList;
+  pipeline_desc.primitive.cullMode = WGPUCullMode_None;
+  pipeline_desc.depthStencil = &depth_stencil;
+  pipeline_desc.multisample.count = 1;
+  pipeline_desc.multisample.mask = 0xFFFFFFFF;
+  pipeline_desc.fragment = &frag;
+
+  pipeline_ = wgpuDeviceCreateRenderPipeline(ctx_.device, &pipeline_desc);
+  wgpuShaderModuleRelease(module);
+
+  WGPUTextureView prev_view = demo_->get_prev_texture_view();
+  const WGPUBindGroupEntry entries[] = {
+      {.binding = 0, .sampler = sampler_},
+      {.binding = 1, .textureView = prev_view},
+      {.binding = 2,
+       .buffer = uniforms_.get().buffer,
+       .size = sizeof(CommonPostProcessUniforms)},
+      {.binding = 3,
+       .buffer = params_.get().buffer,
+       .size = sizeof(ShaderToyParams)},
+  };
+  const WGPUBindGroupDescriptor bg_desc = {
+      .layout = wgpuRenderPipelineGetBindGroupLayout(pipeline_, 0),
+      .entryCount = 4,
+      .entries = entries,
+  };
+  bind_group_ = wgpuDeviceCreateBindGroup(ctx_.device, &bg_desc);
+}
+
+void ShaderToyEffect::render(WGPURenderPassEncoder pass, float time,
+                              float beat, float intensity, float aspect_ratio) {
+  const CommonPostProcessUniforms uniforms = {
+      .resolution = {static_cast<float>(width_), static_cast<float>(height_)},
+      .aspect_ratio = aspect_ratio,
+      .time = time,
+      .beat = beat,
+      .audio_intensity = intensity,
+  };
+  uniforms_.update(ctx_.queue, uniforms);
+
+  // TODO: Update parameters based on your effect
+  const ShaderToyParams params = {
+      .param1 = 1.0f,
+      .param2 = beat,
+  };
+  params_.update(ctx_.queue, params);
+
+  wgpuRenderPassEncoderSetPipeline(pass, pipeline_);
+  wgpuRenderPassEncoderSetBindGroup(pass, 0, bind_group_, 0, nullptr);
+  wgpuRenderPassEncoderDraw(pass, 3, 1, 0, 0);
+}