accumulator blur

shaders/msl/accumulator.frag.msl

@@ -0,0 +1,26 @@
+#include <metal_stdlib>
+using namespace metal;
+
+struct FragmentIn {
+  float4 position [[position]];
+  float2 uv;
+};
+
+struct Uniforms {
+  float decay;
+  float3 padding;
+};
+
+fragment float4 fragment_main(
+  FragmentIn in [[stage_in]],
+  texture2d<float> current_tex [[texture(0)]],
+  texture2d<float> accum_tex [[texture(1)]],
+  sampler samp [[sampler(0)]],
+  constant Uniforms &u [[buffer(0)]]
+) {
+  float4 current = current_tex.sample(samp, in.uv);
+  float4 accum = accum_tex.sample(samp, in.uv);
+  
+  // Ghosting style motion blur
+  return max(current, accum * u.decay);
+}