From d3c4a125845cc1d5767bd86e11ba23c64b70ec89 Mon Sep 17 00:00:00 2001
From: Alexander Gauggel <agauggel@uni-koblenz.de>
Date: Fri, 20 Aug 2021 17:28:55 +0200
Subject: [PATCH] [#106] Replace motion tile offset noise with unaligned dither
for less visible noise
---
.../resources/shaders/motionBlur.comp | 23 ++++---------------
projects/indirect_dispatch/src/App.cpp | 2 +-
2 files changed, 5 insertions(+), 20 deletions(-)
diff --git a/projects/indirect_dispatch/resources/shaders/motionBlur.comp b/projects/indirect_dispatch/resources/shaders/motionBlur.comp
index 804c0ceb..503a7afa 100644
--- a/projects/indirect_dispatch/resources/shaders/motionBlur.comp
+++ b/projects/indirect_dispatch/resources/shaders/motionBlur.comp
@@ -113,34 +113,18 @@ SampleData loadSampleData(vec2 uv){
return data;
}
+const int ditherSize = 4;
+
// simple binary dither pattern
// could be optimized to avoid modulo and branch
float dither(ivec2 coord){
- int ditherSize = 4;
-
bool x = coord.x % ditherSize < (ditherSize / 2);
bool y = coord.y % ditherSize < (ditherSize / 2);
return x ^^ y ? 1 : 0;
}
-// from https://www.shadertoy.com/view/ttc3zr
-uvec2 murmurHash22(uvec2 src) {
- const uint M = 0x5bd1e995u;
- uvec2 h = uvec2(1190494759u, 2147483647u);
- src *= M; src ^= src>>24u; src *= M;
- h *= M; h ^= src.x; h *= M; h ^= src.y;
- h ^= h>>13u; h *= M; h ^= h>>15u;
- return h;
-}
-
-vec2 hash22(vec2 src) {
- uvec2 h = murmurHash22(floatBitsToUint(src));
- return uintBitsToFloat(h & 0x007fffffu | 0x3f800000u) - 1.0;
-}
-
-
void main(){
if(any(greaterThanEqual(gl_GlobalInvocationID.xy, imageSize(outImage))))
@@ -151,7 +135,8 @@ void main(){
vec2 uv = vec2(coord + 0.5) / textureRes; // + 0.5 to shift uv into pixel center
// the motion tile lookup is jittered, so the hard edges in the blur are replaced by noise
- vec2 motionOffset = motionTileOffsetLength * (hash22(coord) * 2 - 1) / textureRes;
+ // dither is shifted, so it does not line up with motion tiles
+ vec2 motionOffset = motionTileOffsetLength * (dither(coord + ivec2(ditherSize / 2)) * 2 - 1) / textureRes;
vec2 motionNeighbourhoodMax = processMotionVector(texture(sampler2D(inMotionNeighbourhoodMax, nearestSampler), uv + motionOffset).rg);
SampleData mainPixel = loadSampleData(uv);
diff --git a/projects/indirect_dispatch/src/App.cpp b/projects/indirect_dispatch/src/App.cpp
index 230ef92c..cc7bff04 100644
--- a/projects/indirect_dispatch/src/App.cpp
+++ b/projects/indirect_dispatch/src/App.cpp
@@ -97,7 +97,7 @@ void App::run() {
eMotionVectorMode motionBlurMotionMode = eMotionVectorMode::MaxTileNeighbourhood;
bool freezeFrame = false;
- float motionBlurTileOffsetLength = 10;
+ float motionBlurTileOffsetLength = 3;
float objectVerticalSpeed = 5;
float objectAmplitude = 0;
float objectMeanHeight = 1;
--
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