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, 52 insertions, 0 deletions

diff --git a/src/gpu/effects/particles_effect.cc b/src/gpu/effects/particles_effect.cc
new file mode 100644
index 0000000..545fdfb
--- /dev/null
+++ b/src/gpu/effects/particles_effect.cc
@@ -0,0 +1,52 @@
+// This file is part of the 64k demo project.
+// It implements the ParticlesEffect.
+
+#include "gpu/demo_effects.h"
+#include "gpu/gpu.h"
+#include <vector>
+
+// --- ParticlesEffect ---
+ParticlesEffect::ParticlesEffect(WGPUDevice device, WGPUQueue queue,
+                                 WGPUTextureFormat format)
+    : queue_(queue) {
+  uniforms_ =
+      gpu_create_buffer(device, sizeof(float) * 4,
+                        WGPUBufferUsage_Uniform | WGPUBufferUsage_CopyDst);
+  std::vector<Particle> init_p(NUM_PARTICLES);
+  particles_buffer_ = gpu_create_buffer(
+      device, sizeof(Particle) * NUM_PARTICLES,
+      WGPUBufferUsage_Storage | WGPUBufferUsage_Vertex, init_p.data());
+  ResourceBinding cb[] = {{particles_buffer_, WGPUBufferBindingType_Storage},
+                          {uniforms_, WGPUBufferBindingType_Uniform}};
+  compute_pass_ = gpu_create_compute_pass(device, particle_compute_wgsl, cb, 2);
+  compute_pass_.workgroup_size_x = (NUM_PARTICLES + 63) / 64;
+  ResourceBinding rb[] = {
+      {particles_buffer_, WGPUBufferBindingType_ReadOnlyStorage},
+      {uniforms_, WGPUBufferBindingType_Uniform}};
+  render_pass_ =
+      gpu_create_render_pass(device, format, particle_render_wgsl, rb, 2);
+  render_pass_.vertex_count = 6;
+  render_pass_.instance_count = NUM_PARTICLES;
+}
+void ParticlesEffect::compute(WGPUCommandEncoder e, float t, float b, float i,
+                              float a) {
+  struct {
+    float p, a, t, d;
+  } u = {i, a, t, 0.0f};
+  wgpuQueueWriteBuffer(queue_, uniforms_.buffer, 0, &u, sizeof(u));
+  WGPUComputePassEncoder pass = wgpuCommandEncoderBeginComputePass(e, nullptr);
+  wgpuComputePassEncoderSetPipeline(pass, compute_pass_.pipeline);
+  wgpuComputePassEncoderSetBindGroup(pass, 0, compute_pass_.bind_group, 0,
+                                     nullptr);
+  wgpuComputePassEncoderDispatchWorkgroups(pass, compute_pass_.workgroup_size_x,
+                                           1, 1);
+  wgpuComputePassEncoderEnd(pass);
+}
+void ParticlesEffect::render(WGPURenderPassEncoder pass, float t, float b,
+                             float i, float a) {
+  wgpuRenderPassEncoderSetPipeline(pass, render_pass_.pipeline);
+  wgpuRenderPassEncoderSetBindGroup(pass, 0, render_pass_.bind_group, 0,
+                                    nullptr);
+  wgpuRenderPassEncoderDraw(pass, render_pass_.vertex_count,
+                            render_pass_.instance_count, 0, 0);
+}