From 05b7e6975e12587164e94cc4d8792571f8acb31a Mon Sep 17 00:00:00 2001
From: Adrian Kummerlaender
Date: Thu, 24 May 2018 22:20:48 +0200
Subject: Improve compute shader structure
---
src/shader/compute.glsl | 48 +++++++++++++++++++++++++++++++++++++-----------
1 file changed, 37 insertions(+), 11 deletions(-)
diff --git a/src/shader/compute.glsl b/src/shader/compute.glsl
index e322a08..d8714b6 100644
--- a/src/shader/compute.glsl
+++ b/src/shader/compute.glsl
@@ -6,8 +6,33 @@ layout (std430, binding=1) buffer bufferA{ float data[]; };
uniform vec2 world;
-float rand(vec2 co){
- return fract(sin(dot(co.xy, vec2(12.9898,78.233))) * 43758.5453);
+// vector field definition
+
+vec2 f(vec2 v) {
+ return vec2(
+ cos(v.x*sin(v.y)),
+ sin(v.x-v.y)
+ );
+}
+
+// ODE solver
+
+vec2 explicitEuler(float h, vec2 v) {
+ return v + h * f(v);
+}
+
+// pseudo random numbers for particle placement
+
+float rand(vec2 v){
+ return fract(sin(dot(v, vec2(12.9898,78.233))) * 43758.5453);
+}
+
+float mapUnitToWorldX(float s) {
+ return -(world.x/2.) + s * world.x;
+}
+
+float mapUnitToWorldY(float s) {
+ return -(world.y/2.) + s * world.y;
}
bool insideWorld(vec2 v) {
@@ -18,17 +43,18 @@ bool insideWorld(vec2 v) {
}
void main() {
- uint idx = 3*gl_GlobalInvocationID.x;
- vec2 v = vec2(data[idx+0], data[idx+1]);
+ const uint i = 3*gl_GlobalInvocationID.x;
+ const vec2 v = vec2(data[i+0], data[i+1]);
+ const vec2 w = explicitEuler(0.01, v);
- if ( data[idx+2] < 5. && insideWorld(v) ) {
- data[idx+0] += 0.01 * cos(v.x*sin(v.y));
- data[idx+1] += 0.01 * sin(v.x-v.y);
- data[idx+2] += 0.01;
+ if ( data[i+2] < 5. && insideWorld(v) ) {
+ data[i+0] = w.x;
+ data[i+1] = w.y;
+ data[i+2] += 0.01;
} else {
- data[idx+0] = -(world.x/2.) + rand(vec2(data[idx+1], data[idx+0])) * world.x;
- data[idx+1] = -(world.y/2.) + rand(vec2(data[idx+0], data[idx+1])) * world.y;
- data[idx+2] = uint(rand(v) * 5.);
+ data[i+0] = mapUnitToWorldX(rand(v));
+ data[i+1] = mapUnitToWorldY(rand(w));
+ data[i+2] = rand(v+w) * 5.;
}
}
)";
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