Added original SDK code for Alien Swarm.

public/mathlib/noise.h

@@ -0,0 +1,35 @@
+//========= Copyright <20> 1996-2006, Valve Corporation, All rights reserved. ============//
+//
+// Purpose: 
+//
+//=====================================================================================//
+
+#ifndef NOISE_H
+#define NOISE_H
+
+#include <math.h>
+#include "basetypes.h"
+#include "mathlib/vector.h"
+#include "tier0/dbg.h"
+
+
+// The following code is the c-ification of Ken Perlin's new noise algorithm
+// "JAVA REFERENCE IMPLEMENTATION OF IMPROVED NOISE - COPYRIGHT 2002 KEN PERLIN"
+// as available here: http://mrl.nyu.edu/~perlin/noise/
+// it generates a single octave of noise in the -1..1 range
+// this should at some point probably replace SparseConvolutionNoise - jd
+float ImprovedPerlinNoise( Vector const &pnt );
+
+// get the noise value at a point. Output range is 0..1.
+float SparseConvolutionNoise( Vector const &pnt );
+
+// get the noise value at a point, passing a custom noise shaping function. The noise shaping
+// function should map the domain 0..1 to 0..1.
+float SparseConvolutionNoise(Vector const &pnt, float (*pNoiseShapeFunction)(float) );
+
+// returns a 1/f noise. more octaves take longer
+float FractalNoise( Vector const &pnt, int n_octaves );
+
+// returns a abs(f)*1/f noise i.e. turbulence
+float Turbulence( Vector const &pnt, int n_octaves );
+#endif // NOISE_H