refactor(effects): Factor shared initialization into Effect base class

Eliminate ~100 lines of duplicated code across effect subclasses by moving common resource initialization to the base Effect class. Most effects repeatedly created uniforms buffers, samplers, and dummy textures with identical configurations.

Changes:
- Add shared members to Effect: uniforms_buffer_, sampler_, dummy_texture_*
- Add helpers: init_uniforms_buffer(), create_*_sampler(), create_dummy_scene_texture()
- Add gpu_create_*_sampler() and gpu_create_dummy_scene_texture() to gpu.h
- Move HEADLESS_RETURN_IF_NULL to Effect constructor
- Update 7 effects to use base class helpers (Flash, Heptagon, Passthrough, Placeholder, GaussianBlur, Particles, PeakMeter)

Benefits: Improved consistency, easier maintenance, reduced binary size.

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

1 files changed, 4 insertions, 26 deletions

diff --git a/src/effects/heptagon_effect.cc b/src/effects/heptagon_effect.cc
index c472f2f..46d6f7f 100644
--- a/src/effects/heptagon_effect.cc
+++ b/src/effects/heptagon_effect.cc
@@ -10,37 +10,15 @@ Heptagon::Heptagon(const GpuContext& ctx,
                    const std::vector<std::string>& inputs,
                    const std::vector<std::string>& outputs, float start_time,
                            float end_time)
-    : Effect(ctx, inputs, outputs, start_time, end_time), pipeline_(nullptr), bind_group_(nullptr),
-      sampler_(nullptr) {
-  // Headless mode: skip GPU resource creation (compiled out in STRIP_ALL)
+    : Effect(ctx, inputs, outputs, start_time, end_time), pipeline_(nullptr), bind_group_(nullptr) {
   HEADLESS_RETURN_IF_NULL(ctx_.device);
 
-  // Init uniforms
-  uniforms_buffer_.init(ctx_.device);
+  init_uniforms_buffer();
+  create_nearest_sampler();
+  create_dummy_scene_texture();
 
-  // Create pipeline (standard post-process, no depth)
   pipeline_ = create_post_process_pipeline(
       ctx_.device, WGPUTextureFormat_RGBA8Unorm, heptagon_shader_wgsl);
-
-  // Create dummy sampler (scene effects don't use texture input)
-  WGPUSamplerDescriptor sampler_desc = {};
-  sampler_desc.addressModeU = WGPUAddressMode_ClampToEdge;
-  sampler_desc.addressModeV = WGPUAddressMode_ClampToEdge;
-  sampler_desc.magFilter = WGPUFilterMode_Nearest;
-  sampler_desc.minFilter = WGPUFilterMode_Nearest;
-  sampler_desc.maxAnisotropy = 1;
-  sampler_ = wgpuDeviceCreateSampler(ctx_.device, &sampler_desc);
-
-  // Create 1×1 dummy texture
-  WGPUTextureDescriptor tex_desc = {};
-  tex_desc.size = {1, 1, 1};
-  tex_desc.format = WGPUTextureFormat_RGBA8Unorm;
-  tex_desc.usage = WGPUTextureUsage_TextureBinding;
-  tex_desc.dimension = WGPUTextureDimension_2D;
-  tex_desc.mipLevelCount = 1;
-  tex_desc.sampleCount = 1;
-  dummy_texture_ = wgpuDeviceCreateTexture(ctx_.device, &tex_desc);
-  dummy_texture_view_ = wgpuTextureCreateView(dummy_texture_, nullptr);
 }
 
 Heptagon::~Heptagon() {