1 files changed, 77 insertions, 0 deletions
diff --git a/shaders/gradient.comp b/shaders/gradient.comp
new file mode 100644
index 0000000..e49a86b
--- /dev/null
+++ b/shaders/gradient.comp
@@ -0,0 +1,77 @@
+#version 450
+#extension GL_ARB_separate_shader_objects : enable
+
+#define WIDTH 3200
+#define HEIGHT 2400
+#define WORKGROUP_SIZE 32
+layout (local_size_x = WORKGROUP_SIZE, local_size_y = WORKGROUP_SIZE, local_size_z = 1 ) in;
+
+layout ( binding = 0, rgba8 ) uniform writeonly image2D buf;
+
+void main() {
+
+  /*
+  In order to fit the work into workgroups, some unnecessary threads are launched.
+  We terminate those threads here.
+  */
+  if(gl_GlobalInvocationID.x >= WIDTH || gl_GlobalInvocationID.y >= HEIGHT)
+	return;
+
+  float x = float(gl_GlobalInvocationID.x) / float(WIDTH);
+  float y = float(gl_GlobalInvocationID.y) / float(HEIGHT);
+
+  /*
+  What follows is code for rendering the mandelbrot set.
+  */
+  vec2 uv = vec2(x,y);
+  float n = 0.0;
+  vec2 c = vec2(-.445, 0.0) +  (uv - 0.5)*(2.0+ 1.7*0.2  ),
+  z = vec2(0.0);
+  const int M =128;
+  for (int i = 0; i<M; i++)
+  {
+	z = vec2(z.x*z.x - z.y*z.y, 2.*z.x*z.y) + c;
+	if (dot(z, z) > 2) break;
+	n++;
+  }
+
+  // we use a simple cosine palette to determine color:
+  // http://iquilezles.org/www/articles/palettes/palettes.htm
+  float t = float(n) / float(M);
+  vec3 d = vec3(0.3, 0.3 ,0.5);
+  vec3 e = vec3(-0.2, -0.3 ,-0.5);
+  vec3 f = vec3(2.1, 2.0, 3.0);
+  vec3 g = vec3(0.0, 0.1, 0.0);
+  vec4 color = vec4( d + e*cos( 6.28318*(f*t+g) ) ,1.0);
+
+
+  imageStore(buf, ivec2(gl_GlobalInvocationID.xy), color);
+}
+/*
+uniform float windowHeight;
+
+uniform vec2  gradientStartPos;
+uniform vec2  gradientEndPos;
+uniform int   numStops;
+uniform vec4  colors[16];
+uniform float stops[16];
+
+void main() {
+
+	float  alpha = atan( -gradientEndPos.y + gradientStartPos.y, gradientEndPos.x - gradientStartPos.x );
+	float  gradientStartPosRotatedX = gradientStartPos.x*cos(alpha) - gradientStartPos.y*sin(alpha);
+	float  gradientEndPosRotatedX   = gradientEndPos.x*cos(alpha) - gradientEndPos.y*sin(alpha);
+	float  d = gradientEndPosRotatedX - gradientStartPosRotatedX;
+
+
+	float y = windowHeight - gl_FragCoord.y;
+	float x = gl_FragCoord.x;
+	float xLocRotated = x*cos( alpha ) - y*sin( alpha );
+
+	gl_FragColor = mix(colors[0], colors[1], smoothstep( gradientStartPosRotatedX + stops[0]*d, gradientStartPosRotatedX + stops[1]*d, xLocRotated ) );
+	for ( int i=1; i<numStops-1; ++i ) {
+		gl_FragColor = mix(gl_FragColor, colors[i+1], smoothstep( gradientStartPosRotatedX + stops[i]*d, gradientStartPosRotatedX + stops[i+1]*d, xLocRotated ) );
+	}
+
+
+}*/