1 files changed, 45 insertions, 0 deletions
diff --git a/src/effects/flash_effect.h b/src/effects/flash_effect.h
new file mode 100644
index 0000000..1ac75a4
--- /dev/null
+++ b/src/effects/flash_effect.h
@@ -0,0 +1,45 @@
+// This file is part of the 64k demo project.
+// It declares the FlashEffect - brief white flash on beat hits.
+
+#pragma once
+
+#include "gpu/effect.h"
+#include "gpu/gpu.h"
+#include "gpu/uniform_helper.h"
+
+// Parameters for FlashEffect (set at construction time)
+struct FlashEffectParams {
+  float color[3] = {1.0f, 1.0f, 1.0f}; // Default: white
+  float decay_rate = 0.98f;            // Default: fast decay
+  float trigger_threshold = 0.7f;      // Default: trigger on strong beats
+};
+
+// Uniform data sent to GPU shader
+// IMPORTANT: Must match WGSL struct layout with proper alignment
+// vec3<f32> in WGSL has 16-byte alignment, not 12-byte!
+struct FlashUniforms {
+  float flash_intensity; // offset 0
+  float intensity;       // offset 4
+  float _pad1[2];        // offset 8-15 (padding for vec3 alignment)
+  float color[3];        // offset 16-27 (vec3 aligned to 16 bytes)
+  float _pad2;           // offset 28-31
+};
+static_assert(sizeof(FlashUniforms) == 32,
+              "FlashUniforms must be 32 bytes for WGSL alignment");
+
+class FlashEffect : public PostProcessEffect {
+ public:
+  // Backward compatibility constructor (uses default params)
+  FlashEffect(const GpuContext& ctx);
+  // New parameterized constructor
+  FlashEffect(const GpuContext& ctx, const FlashEffectParams& params);
+  void render(WGPURenderPassEncoder pass,
+              const CommonPostProcessUniforms& uniforms) override;
+  void update_bind_group(WGPUTextureView input_view) override;
+
+ private:
+  FlashEffectParams params_;
+  UniformBuffer<FlashUniforms> flash_uniforms_;
+  UniformBuffer<FlashEffectParams> params_buffer_;
+  float flash_intensity_ = 0.0f;
+};