From 51330d76cd6388804ee96b59a3d7339d30016b7b Mon Sep 17 00:00:00 2001
From: Alexander Gauggel <agauggel@uni-koblenz.de>
Date: Mon, 16 Aug 2021 21:32:34 +0200
Subject: [PATCH] [#106] Add motion blur filter jitter to reduce banding
---
.../resources/shaders/motionBlur.comp | 23 +++++++++++++++++--
projects/indirect_dispatch/src/App.cpp | 6 +++--
2 files changed, 25 insertions(+), 4 deletions(-)
diff --git a/projects/indirect_dispatch/resources/shaders/motionBlur.comp b/projects/indirect_dispatch/resources/shaders/motionBlur.comp
index 713a8775..233947d1 100644
--- a/projects/indirect_dispatch/resources/shaders/motionBlur.comp
+++ b/projects/indirect_dispatch/resources/shaders/motionBlur.comp
@@ -15,6 +15,7 @@ layout( push_constant ) uniform constants{
// camera planes are needed to linearize depth
float cameraNearPlane;
float cameraFarPlane;
+ float time;
};
float linearizeDepth(float depth, float near, float far){
@@ -76,6 +77,21 @@ SampleData loadSampleData(vec2 uv){
return data;
}
+// simple hash/noise function from: https://www.shadertoy.com/view/ttc3zr
+uint murmurHash12(uvec2 src) {
+ const uint M = 0x5bd1e995u;
+ uint h = 1190494759u;
+ 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;
+}
+
+float hash12(vec2 src) {
+ uint h = murmurHash12(floatBitsToUint(src));
+ return uintBitsToFloat(h & 0x007fffffu | 0x3f800000u) - 1.0;
+}
+
void main(){
if(any(greaterThanEqual(gl_GlobalInvocationID.xy, imageSize(outImage))))
@@ -89,7 +105,7 @@ void main(){
// early out on little movement
if(mainPixel.velocity <= minVelocity){
- vec3 color = texture(sampler2D(inColor, nearestSampler), uv).rgb;
+ vec3 color = texture(sampler2D(inColor, nearestSampler), uv).rgb;
imageStore(outImage, coord, vec4(color, 0.f));
return;
}
@@ -109,8 +125,11 @@ void main(){
vec2 uvStart = clamp(uv - mainPixel.motion, 0, 1);
vec2 uvEnd = clamp(uv + mainPixel.motion, 0, 1);
+ // samples are placed evenly, but the entire filter is jittered
+ float random = hash12(uv + time) - 0.5; // in range [-0.5, 0.5]
+
for(int i = 0; i < sampleCount; i++){
- vec2 sampleUV = mix(uvStart, uvEnd, i / float(sampleCount - 1));
+ vec2 sampleUV = mix(uvStart, uvEnd, (i + random + 1) / float(sampleCount + 1));
vec3 sampleColor = texture(sampler2D(inColor, nearestSampler), sampleUV).rgb;
SampleData samplePixel = loadSampleData(sampleUV);
diff --git a/projects/indirect_dispatch/src/App.cpp b/projects/indirect_dispatch/src/App.cpp
index 69b5db3e..0856173a 100644
--- a/projects/indirect_dispatch/src/App.cpp
+++ b/projects/indirect_dispatch/src/App.cpp
@@ -305,6 +305,7 @@ void App::run() {
float minVelocity;
float cameraNearPlane;
float cameraFarPlane;
+ float time;
};
MotionBlurConstantData motionBlurConstantData;
@@ -320,8 +321,9 @@ void App::run() {
float cameraNear, cameraFar;
m_cameraManager.getActiveCamera().getNearFar(cameraNear, cameraFar);
- motionBlurConstantData.cameraNearPlane = cameraNear;
- motionBlurConstantData.cameraFarPlane = cameraFar;
+ motionBlurConstantData.cameraNearPlane = cameraNear;
+ motionBlurConstantData.cameraFarPlane = cameraFar;
+ motionBlurConstantData.time = fCurrentTime;
vkcv::PushConstants motionBlurPushConstants(sizeof(motionBlurConstantData));
motionBlurPushConstants.appendDrawcall(motionBlurConstantData);
--
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