www.pudn.com > simpleraytracer_v1_0.zip > mathstypes.h

/*=================================================================== 
 
   
  digital liberation front 2001 
   
  _______    ______      _______ 
 /______/\  |______|    /\______\   
|       \ \ |      |   / /       |     
|	      \| |      |  |/         |   
|_____    \ |      |_ /    ______|        
 ____|    | |      |_||    |_____           
     |____| |________||____|                 
            
 
 
 
Code by Nicholas Chapman 
nickamy@paradise.net.nz 
 
You may use this code for any non-commercial project, 
as long as you do not remove this description. 
 
You may not use this code for any commercial project. 
====================================================================*/ 
#ifndef __MATHSTYPES_H__ 
#define __MATHSTYPES_H__ 
 
#include  
 
const float NICKMATHS_EPSILON = 0.00001f; 
 
//from Ipion 
const float NICKMATHS_PI = 3.14159265358979323846f; 
 
const float NICKMATHS_2PI = NICKMATHS_PI * 2; 
 
const float NICKMATHS_PI_2 = NICKMATHS_PI / 2; 
const float NICKMATHS_PI_4 = NICKMATHS_PI / 4; 
 
inline bool epsEqual(float a, float b) 
{ 
	//NOTE: this could be much better 
 	const float absdif = (float)fabs(a - b); 
 
	if(absdif <= NICKMATHS_EPSILON) 
		return true; 
	else 
		return false; 
} 
 
inline bool epsEqual(float a, float b, float epsilon) 
{ 
	//NOTE: this could be much better 
 	const float absdif = (float)fabs(a - b); 
 
	if(absdif <= epsilon) 
		return true; 
	else 
		return false; 
} 
 
inline float radToDegree(float rad) 
{ 
	return rad * 180.0f / NICKMATHS_PI;	 
} 
 
inline float degreeToRad(float degree) 
{ 
	return degree * NICKMATHS_PI / 180.0f; 
} 
 
 
inline float absoluteVal(float x) 
{ 
	if(x < 0) 
		return -x; 
	else 
		return x; 
} 
 
 
inline float raiseBy2toN(float x, int n) 
{ 
	//----------------------------------------------------------------- 
	//isolate exponent bits 
	//----------------------------------------------------------------- 
	unsigned int exponent_bits = *((int*)&x) & 0x7F400000; 
 
	//----------------------------------------------------------------- 
	//bitshift them 
	//----------------------------------------------------------------- 
	exponent_bits >>= n; 
 
	//----------------------------------------------------------------- 
	//blank out old bits 
	//----------------------------------------------------------------- 
	*((int*)&x) &= 0x8001FFFF; 
 
	//----------------------------------------------------------------- 
	//copy new bits in 
	//----------------------------------------------------------------- 
	*((int*)&x) &= exponent_bits; 
 
	return x; 
} 
 
 
 
 
 
// Fast reciprocal square root 
//posted by DarkWIng on Flipcode 
 
__inline float RSqrt( float number )  
{ 
	long i; 
	float x2, y; 
	const float threehalfs = 1.5f; 
 
	x2 = number * 0.5f; 
	y  = number; 
	i  = * (long *) &y;			// evil floating point bit level hacking 
	i  = 0x5f3759df - (i >> 1);             // what the f..k? 
	y  = * (float *) &i; 
	y  = y * (threehalfs - (x2 * y * y));   // 1st iteration 
 
	return y; 
} 
 
 
 
#endif //__MATHSTYPES_H__