Adding some helper GLSL functions

shaders/Clusterer.glsl

@@ -0,0 +1,41 @@
+// Copyright (C) 2009-2015, Panagiotis Christopoulos Charitos.
+// All rights reserved.
+// Code licensed under the BSD License.
+// http://www.anki3d.org/LICENSE
+
+// Contains functions for the clusterer
+
+#ifndef ANKI_SHADERS_CLUSTERER_GLSL
+#define ANKI_SHADERS_CLUSTERER_GLSL
+
+#pragma anki include "shaders/Common.glsl"
+
+//==============================================================================
+// Compute the cluster index using the tile index.
+uint computeClusterIndexUsingTileIdx(float near, float clustererMagic,
+	float zVSpace, uint tileIdx)
+{
+	float fk = sqrt((near + zVSpace) * clustererMagic);
+	uint k = uint(fk);
+
+	return tileIdx + k;
+}
+
+//==============================================================================
+// Compute the cluster index using the gl_FragCoord.xy.
+uint computeClusterIndexUsingFragCoord(float near, float clustererMagic,
+	float zVSpace, uint tileCountX)
+{
+#if TILE_SIZE != 64
+#	error Not designed for this tile size
+#endif
+
+	// Compute tile idx
+	uvec2 f = uvec2(gl_FragCoord.xy) >> 6;
+	uint tileIdx = f.y * tileCountX + f.x;
+
+	return computeClusterIndexUsingTileIdx(near, clustererMagic, zVSpace,
+		tileIdx);
+}
+
+#endif