#define PI 3.14159265359
#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


uniform mat4 modelMatrix;
uniform mat4 modelViewMatrix;
uniform mat4 projectionMatrix;
uniform mat4 viewMatrix;
uniform mat3 normalMatrix;
uniform vec3 cameraPosition;
uniform bool isOrthographic;

#ifdef USE_INSTANCING
 attribute mat4 instanceMatrix;
#endif
attribute vec3 position;
attribute vec3 normal;
attribute vec2 uv;
#ifdef USE_TANGENT
	attribute vec4 tangent;
#endif
#ifdef USE_COLOR
	attribute vec3 color;
#endif

varying vec3 vViewPosition;
#ifndef FLAT_SHADED
	varying vec3 vNormal;
	#ifdef USE_TANGENT
		varying vec3 vTangent;
		varying vec3 vBitangent;
	#endif
#endif


bool isPerspectiveMatrix( mat4 m ) {
  return m[ 2 ][ 3 ] == - 1.0;
}