#define PI 3.1415926535897932384626433832795
#define PI2 6.28318530718
#define PI_HALF 1.5707963267949
#define RECIPROCAL_PI 0.31830988618
#define RECIPROCAL_PI2 0.15915494
#define LOG2 1.442695
#define EPSILON 1e-6

#define saturate(a) clamp( a, 0.0, 1.0 )
#define whiteCompliment(a) ( 1.0 - saturate( a ) )

float pow2( const in float x ) { return x*x; }
float pow3( const in float x ) { return x*x*x; }
float pow4( const in float x ) { float x2 = x*x; return x2*x2; }
float average( const in vec3 color ) { return dot( color, vec3( 0.3333 ) ); }
// expects values in the range of [0,1]x[0,1], returns values in the [0,1] range.
// do not collapse into a single function per: http://byteblacksmith.com/improvements-to-the-canonical-one-liner-glsl-rand-for-opengl-es-2-0/
highp float rand( const in vec2 uv ) {
	const highp float a = 12.9898, b = 78.233, c = 43758.5453;
	highp float dt = dot( uv.xy, vec2( a,b ) ), sn = mod( dt, PI );
	return fract(sin(sn) * c);
}
