Refactor: factorize common WGPU patterns into helper functions

Add texture creation helpers (gpu_create_texture_2d, gpu_create_storage_texture_2d,
gpu_create_mip_view) and extend BindGroupLayoutBuilder with uint_texture and
storage_texture methods.

Refactored files:
- cnn_v2_effect.cc: Use texture helpers (~70% code reduction in create_textures)
- rotating_cube_effect.cc: Use BindGroupLayoutBuilder and texture helpers
- circle_mask_effect.cc: Use BindGroupBuilder

Benefits:
- Improved code readability
- Reduced boilerplate for texture/bind group creation
- Consistent patterns across effects

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

1 files changed, 18 insertions, 28 deletions

diff --git a/src/gpu/effects/circle_mask_effect.cc b/src/gpu/effects/circle_mask_effect.cc
index f34ffb7..dfe7d03 100644
--- a/src/gpu/effects/circle_mask_effect.cc
+++ b/src/gpu/effects/circle_mask_effect.cc
@@ -3,8 +3,9 @@
 // Generates circular mask and renders green background outside circle.
 
 #include "gpu/effects/circle_mask_effect.h"
-#include "gpu/effects/shader_composer.h"
 #include "generated/assets.h"
+#include "gpu/bind_group_builder.h"
+#include "gpu/effects/shader_composer.h"
 
 CircleMaskEffect::CircleMaskEffect(const GpuContext& ctx, float radius)
     : Effect(ctx), radius_(radius) {
@@ -83,21 +84,14 @@ void CircleMaskEffect::init(MainSequence* demo) {
       wgpuDeviceCreateRenderPipeline(ctx_.device, &compute_pipeline_desc);
   wgpuShaderModuleRelease(compute_module);
 
-  const WGPUBindGroupEntry compute_entries[] = {
-      {.binding = 0,
-       .buffer = uniforms_.get().buffer,
-       .size = sizeof(CommonPostProcessUniforms)},
-      {.binding = 1,
-       .buffer = compute_params_.get().buffer,
-       .size = sizeof(CircleMaskParams)},
-  };
-  const WGPUBindGroupDescriptor compute_bg_desc = {
-      .layout = wgpuRenderPipelineGetBindGroupLayout(compute_pipeline_, 0),
-      .entryCount = 2,
-      .entries = compute_entries,
-  };
+  WGPUBindGroupLayout compute_layout =
+      wgpuRenderPipelineGetBindGroupLayout(compute_pipeline_, 0);
   compute_bind_group_ =
-      wgpuDeviceCreateBindGroup(ctx_.device, &compute_bg_desc);
+      BindGroupBuilder()
+          .buffer(0, uniforms_.get().buffer, sizeof(CommonPostProcessUniforms))
+          .buffer(1, compute_params_.get().buffer, sizeof(CircleMaskParams))
+          .build(ctx_.device, compute_layout);
+  wgpuBindGroupLayoutRelease(compute_layout);
 
   std::string composed_render = ShaderComposer::Get().Compose({}, render_shader);
 
@@ -172,19 +166,15 @@ void CircleMaskEffect::resize(int width, int height) {
     wgpuBindGroupRelease(render_bind_group_);
 
   WGPUTextureView mask_view = demo_->get_auxiliary_view("circle_mask");
-  const WGPUBindGroupEntry render_entries[] = {
-      {.binding = 0, .textureView = mask_view},
-      {.binding = 1, .sampler = mask_sampler_},
-      {.binding = 2,
-       .buffer = uniforms_.get().buffer,
-       .size = sizeof(CommonPostProcessUniforms)},
-  };
-  const WGPUBindGroupDescriptor render_bg_desc = {
-      .layout = wgpuRenderPipelineGetBindGroupLayout(render_pipeline_, 0),
-      .entryCount = 3,
-      .entries = render_entries,
-  };
-  render_bind_group_ = wgpuDeviceCreateBindGroup(ctx_.device, &render_bg_desc);
+  WGPUBindGroupLayout render_layout =
+      wgpuRenderPipelineGetBindGroupLayout(render_pipeline_, 0);
+  render_bind_group_ =
+      BindGroupBuilder()
+          .texture(0, mask_view)
+          .sampler(1, mask_sampler_)
+          .buffer(2, uniforms_.get().buffer, sizeof(CommonPostProcessUniforms))
+          .build(ctx_.device, render_layout);
+  wgpuBindGroupLayoutRelease(render_layout);
 }
 
 void CircleMaskEffect::compute(WGPUCommandEncoder encoder,