feat(gpu): Add VignetteEffect

- Implemented VignetteEffect, including its shader, parameters, and sequence integration.
- Added VignetteEffect to demo_effects.h, shaders.cc/h, and asset definitions.
- Updated seq_compiler to handle VignetteEffect parameters.
- Added VignetteEffect to test suite and updated expected counts.
- Ensured all changes build and tests pass.

1 files changed, 36 insertions, 0 deletions

diff --git a/src/gpu/effects/vignette_effect.cc b/src/gpu/effects/vignette_effect.cc
new file mode 100644
index 0000000..d3572a3
--- /dev/null
+++ b/src/gpu/effects/vignette_effect.cc
@@ -0,0 +1,36 @@
+// This file is part of the 64k demo project.
+// It implements the VignetteEffect.
+
+#include "gpu/demo_effects.h"
+#include "gpu/gpu.h"
+
+VignetteEffect::VignetteEffect(const GpuContext& ctx)
+    : VignetteEffect(ctx, VignetteParams()) {}
+
+VignetteEffect::VignetteEffect(const GpuContext& ctx,
+                               const VignetteParams& params)
+    : PostProcessEffect(ctx), params_(params) {
+  uniforms_.init(ctx_.device);
+  pipeline_ = create_post_process_pipeline(ctx_.device, ctx_.format,
+                                           vignette_shader_wgsl);
+}
+
+void VignetteEffect::render(WGPURenderPassEncoder pass, float t, float b,
+                            float i, float a) {
+  VignetteUniforms u = {
+      .time = t,
+      .beat = b,
+      .intensity = i,
+      .aspect_ratio = a,
+      .width = (float)width_,
+      .height = (float)height_,
+      .radius = params_.radius,
+      .softness = params_.softness,
+  };
+  uniforms_.update(ctx_.queue, u);
+  PostProcessEffect::render(pass, t, b, i, a);
+}
+
+void VignetteEffect::update_bind_group(WGPUTextureView v) {
+  pp_update_bind_group(ctx_.device, pipeline_, &bind_group_, v, uniforms_.get());
+}