Refactor: Split demo effects and shaders into individual files

Split src/gpu/demo_effects.cc into individual .cc files for each effect
and created separate files for post-processing helpers and WGSL shaders.
Updated src/gpu/demo_effects.h to be a central header for all effect-related
declarations and adjusted CMakeLists.txt accordingly.

1 files changed, 88 insertions, 0 deletions

diff --git a/src/gpu/effects/post_process_helper.cc b/src/gpu/effects/post_process_helper.cc
new file mode 100644
index 0000000..7c64844
--- /dev/null
+++ b/src/gpu/effects/post_process_helper.cc
@@ -0,0 +1,88 @@
+// This file is part of the 64k demo project.
+// It implements helper functions for post-processing effects.
+
+#include "../demo_effects.h"
+#include "gpu/gpu.h"
+#include <cstring>
+
+// Helper to create a standard post-processing pipeline
+WGPURenderPipeline
+create_post_process_pipeline(WGPUDevice device, WGPUTextureFormat format,
+                             const char* shader_code) {
+  WGPUShaderModuleDescriptor shader_desc = {};
+  WGPUShaderSourceWGSL wgsl_src = {};
+  wgsl_src.chain.sType = WGPUSType_ShaderSourceWGSL;
+  wgsl_src.code = str_view(shader_code);
+  shader_desc.nextInChain = &wgsl_src.chain;
+  WGPUShaderModule shader_module =
+      wgpuDeviceCreateShaderModule(device, &shader_desc);
+
+  WGPUBindGroupLayoutEntry bgl_entries[3] = {};
+  bgl_entries[0].binding = 0;
+  bgl_entries[0].visibility = WGPUShaderStage_Fragment;
+  bgl_entries[0].sampler.type = WGPUSamplerBindingType_Filtering;
+  bgl_entries[1].binding = 1;
+  bgl_entries[1].visibility = WGPUShaderStage_Fragment;
+  bgl_entries[1].texture.sampleType = WGPUTextureSampleType_Float;
+  bgl_entries[1].texture.viewDimension = WGPUTextureViewDimension_2D;
+  bgl_entries[2].binding = 2;
+  bgl_entries[2].visibility = WGPUShaderStage_Fragment;
+  bgl_entries[2].buffer.type = WGPUBufferBindingType_Uniform;
+
+  WGPUBindGroupLayoutDescriptor bgl_desc = {};
+  bgl_desc.entryCount = 3;
+  bgl_desc.entries = bgl_entries;
+  WGPUBindGroupLayout bgl = wgpuDeviceCreateBindGroupLayout(device, &bgl_desc);
+
+  WGPUPipelineLayoutDescriptor pl_desc = {};
+  pl_desc.bindGroupLayoutCount = 1;
+  pl_desc.bindGroupLayouts = &bgl;
+  WGPUPipelineLayout pl = wgpuDeviceCreatePipelineLayout(device, &pl_desc);
+
+  WGPUColorTargetState color_target = {};
+  color_target.format = format;
+  color_target.writeMask = WGPUColorWriteMask_All;
+
+  WGPUFragmentState fragment_state = {};
+  fragment_state.module = shader_module;
+  fragment_state.entryPoint = str_view("fs_main");
+  fragment_state.targetCount = 1;
+  fragment_state.targets = &color_target;
+
+  WGPURenderPipelineDescriptor pipeline_desc = {};
+  pipeline_desc.layout = pl;
+  pipeline_desc.vertex.module = shader_module;
+  pipeline_desc.vertex.entryPoint = str_view("vs_main");
+  pipeline_desc.fragment = &fragment_state;
+  pipeline_desc.primitive.topology = WGPUPrimitiveTopology_TriangleList;
+  pipeline_desc.multisample.count = 1;
+  pipeline_desc.multisample.mask = 0xFFFFFFFF;
+
+  return wgpuDeviceCreateRenderPipeline(device, &pipeline_desc);
+}
+
+// --- PostProcess Implementation Helper ---
+void pp_update_bind_group(WGPUDevice device, WGPURenderPipeline pipeline,
+                                 WGPUBindGroup* bind_group,
+                                 WGPUTextureView input_view,
+                                 GpuBuffer uniforms) {
+  if (*bind_group)
+    wgpuBindGroupRelease(*bind_group);
+  WGPUBindGroupLayout bgl = wgpuRenderPipelineGetBindGroupLayout(pipeline, 0);
+  WGPUSamplerDescriptor sd = {};
+  sd.magFilter = WGPUFilterMode_Linear;
+  sd.minFilter = WGPUFilterMode_Linear;
+  sd.maxAnisotropy = 1;
+  WGPUSampler sampler = wgpuDeviceCreateSampler(device, &sd);
+  WGPUBindGroupEntry bge[3] = {};
+  bge[0].binding = 0;
+  bge[0].sampler = sampler;
+  bge[1].binding = 1;
+  bge[1].textureView = input_view;
+  bge[2].binding = 2;
+  bge[2].buffer = uniforms.buffer;
+  bge[2].size = uniforms.size;
+  WGPUBindGroupDescriptor bgd = {
+      .layout = bgl, .entryCount = 3, .entries = bge};
+  *bind_group = wgpuDeviceCreateBindGroup(device, &bgd);
+}