Kelsidavis-WoWee/assets/shaders/fsr2_motion.comp.glsl
Kelsi f74dcc37e0 FSR2: reduce doubling via tighter clamp, MV dead zone, luminance stability
- Motion shader: zero out sub-0.01px motion to eliminate float precision
  noise in reprojection (distant geometry with large world coords)
- Accumulate: tighten neighborhood clamp gamma 3.0→1.5 to catch slightly
  misaligned history causing ghost doubles
- Reduce max jitter-aware blend 30%→20% for less visible oscillation
- Add luminance instability dampening: reduce blend when current frame
  disagrees with history to prevent shimmer on small/distant features
2026-03-08 14:34:58 -07:00

52 lines
2 KiB
GLSL

#version 450
layout(local_size_x = 8, local_size_y = 8) in;
layout(set = 0, binding = 0) uniform sampler2D depthBuffer;
layout(set = 0, binding = 1, rg16f) uniform writeonly image2D motionVectors;
layout(push_constant) uniform PushConstants {
mat4 reprojMatrix; // prevUnjitteredVP * inverse(currentUnjitteredVP)
vec4 resolution; // xy = internal size, zw = 1/internal size
vec4 jitterOffset; // xy = current jitter (NDC), zw = unused
} pc;
void main() {
ivec2 pixelCoord = ivec2(gl_GlobalInvocationID.xy);
ivec2 imgSize = ivec2(pc.resolution.xy);
if (pixelCoord.x >= imgSize.x || pixelCoord.y >= imgSize.y) return;
float depth = texelFetch(depthBuffer, pixelCoord, 0).r;
// Pixel center UV and NDC
vec2 uv = (vec2(pixelCoord) + 0.5) * pc.resolution.zw;
vec2 ndc = uv * 2.0 - 1.0;
// Unjitter the NDC: the scene was rendered with jitter applied to
// projection[2][0/1]. For RH perspective (P[2][3]=-1, clip.w=-vz):
// jittered_ndc = unjittered_ndc - jitter
// unjittered_ndc = ndc + jitter
vec2 unjitteredNDC = ndc + pc.jitterOffset.xy;
// Reproject to previous frame via unjittered VP matrices
vec4 clipPos = vec4(unjitteredNDC, depth, 1.0);
vec4 prevClip = pc.reprojMatrix * clipPos;
vec2 prevNdc = prevClip.xy / prevClip.w;
vec2 prevUV = prevNdc * 0.5 + 0.5;
// Current unjittered UV for this pixel's world content
vec2 currentUnjitteredUV = unjitteredNDC * 0.5 + 0.5;
// Motion between unjittered positions — jitter-free.
// For a static scene (identity reprojMatrix), this is exactly zero.
vec2 motion = prevUV - currentUnjitteredUV;
// Dead zone: sub-pixel motion below 0.01 pixels is floating-point noise
// from reprojMatrix precision (especially for distant geometry where
// large world coords amplify VP inverse errors). Zero it to prevent
// phantom doubling artifacts.
float motionPx = length(motion * pc.resolution.xy);
motion *= step(0.01, motionPx);
imageStore(motionVectors, pixelCoord, vec4(motion, 0.0, 0.0));
}