From f728e4c8d202de241673a13ce61570b6acb4bba7 Mon Sep 17 00:00:00 2001
From: Adrian Kummerlaender
Date: Fri, 25 May 2018 23:47:27 +0200
Subject: Restructure source directory

---
 src/shader/code/compute.glsl | 62 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 62 insertions(+)
 create mode 100644 src/shader/code/compute.glsl

(limited to 'src/shader/code/compute.glsl')

diff --git a/src/shader/code/compute.glsl b/src/shader/code/compute.glsl
new file mode 100644
index 0000000..eaf5579
--- /dev/null
+++ b/src/shader/code/compute.glsl
@@ -0,0 +1,62 @@
+static const std::string COMPUTE_SHADER_CODE = R"(
+#version 430
+
+layout (local_size_x = 1) in;
+layout (std430, binding=1) buffer bufferA{ float data[]; };
+
+uniform vec2 world;
+
+// ODE solver
+
+vec2 f(vec2); // field definition is to be appended
+
+vec2 explicitEuler(float h, vec2 v) {
+	return v + h * f(v);
+}
+
+vec2 classicalRungeKutta(float h, vec2 v) {
+	const vec2 k1 = f(v);
+	const vec2 k2 = f(v + h/2. * k1);
+	const vec2 k3 = f(v + h/2. * k2);
+	const vec2 k4 = f(v + h    * k3);
+
+	return v + h * (1./6.*k1 + 1./3.*k2 + 1./3.*k3 + 1./6.*k4);
+}
+
+// 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) {
+	return v.x > -world.x/2.
+	    && v.x <  world.x/2.
+	    && v.y > -world.y/2.
+	    && v.y <  world.y/2.;
+}
+
+void main() {
+	const uint i = 3*gl_GlobalInvocationID.x;
+	const vec2 v = vec2(data[i+0], data[i+1]);
+	const vec2 w = classicalRungeKutta(0.01, v);
+
+	if ( data[i+2] < 5. && insideWorld(v) ) {
+		data[i+0]  = w.x;
+		data[i+1]  = w.y;
+		data[i+2] += 0.01;
+	} else {
+		data[i+0] = mapUnitToWorldX(rand(v));
+		data[i+1] = mapUnitToWorldY(rand(w));
+		data[i+2] = rand(v+w) * 5.;
+	}
+}
+)";
-- 
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