mathutils.cpp

rps game symbian os application development

#include <e32math.h>
#include "mathutils.h"

// lookup data for sin and cos

// Fast Integer Square Root look up data
LOCAL_D const TInt32 SqrtTable[] = {
         0,    16,  22,  27,  32,  35,  39,  42,  45,  48,  50,  53,  55,  57,
         59,   61,  64,  65,  67,  69,  71,  73,  75,  76,  78,  80,  81,  83,
         84,   86,  87,  89,  90,  91,  93,  94,  96,  97,  98,  99, 101, 102,
         103, 104, 106, 107, 108, 109, 110, 112, 113, 114, 115, 116, 117, 118,
         119, 120, 121, 122, 123, 124, 125, 126, 128, 128, 129, 130, 131, 132,
         133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 144, 145,
         146, 147, 148, 149, 150, 150, 151, 152, 153, 154, 155, 155, 156, 157,
         158, 159, 160, 160, 161, 162, 163, 163, 164, 165, 166, 167, 167, 168,
         169, 170, 170, 171, 172, 173, 173, 174, 175, 176, 176, 177, 178, 178,
         179, 180, 181, 181, 182, 183, 183, 184, 185, 185, 186, 187, 187, 188,
         189, 189, 190, 191, 192, 192, 193, 193, 194, 195, 195, 196, 197, 197,
         198, 199, 199, 200, 201, 201, 202, 203, 203, 204, 204, 205, 206, 206,
         207, 208, 208, 209, 209, 210, 211, 211, 212, 212, 213, 214, 214, 215,
         215, 216, 217, 217, 218, 218, 219, 219, 220, 221, 221, 222, 222, 223,
         224, 224, 225, 225, 226, 226, 227, 227, 228, 229, 229, 230, 230, 231,
         231, 232, 232, 233, 234, 234, 235, 235, 236, 236, 237, 237, 238, 238,
         239, 240, 240, 241, 241, 242, 242, 243, 243, 244, 244, 245, 245, 246,
         246, 247, 247, 248, 248, 249, 249, 250, 250, 251, 251, 252, 252, 253,
         253, 254, 254, 255
      };
   

//
// Fixed point distance calculator
//
TInt MathUtils::Distance(const TPoint& aA, const TPoint& aB)
	{
	TInt xSide = (aB.iX - aA.iX);
	TInt ySide = (aB.iY - aA.iY);
	
	return SquareRoot(xSide*xSide + ySide*ySide);	
	}

//
// Fast fixed point Square root function (using look up table above)
// Not pretty but rather fast 
//
TInt32 MathUtils::SquareRoot(TInt32 x) 
	{
    TInt32 xn;
     
         if (x >= 0x10000) {
            if (x >= 0x1000000) {
               if (x >= 0x10000000) {
                  if (x >= 0x40000000) {
                     if (x >= 65535ul*65535ul) {
                        return 65535;
                     }
                  
                     xn = SqrtTable[x >> 24] << 8;
                  } 
                  else
                  {
                     xn = SqrtTable[x >> 22] << 7;
                  }
               }
               else {
                  if (x >= 0x4000000) {
                     xn = SqrtTable[x >> 20] << 6;
                  }
                  else
                  {
                     xn = SqrtTable[x >> 18] << 5;
                  }
               }
            
               xn = (xn + 1 + (x / xn)) >> 1;
               xn = (xn + 1 + (x / xn)) >> 1;
               return ((xn * xn) > x) ? --xn : xn;
            }
            else
            {
               if (x >= 0x100000) {
                  if (x >= 0x400000) {
                     xn = SqrtTable[x >> 16] << 4;
                  }
                  else
                  {
                     xn = SqrtTable[x >> 14] << 3;
                  }
               }
               else
               {
                  if (x >= 0x40000) {
                     xn = SqrtTable[x >> 12] << 2;
                  }
                  else
                  {
                     xn = SqrtTable[x >> 10] << 1;
                  }
               }
            
               xn = (xn + 1 + (x / xn)) >> 1;
            
               return ((xn * xn) > x) ? --xn : xn;
            }
         }
         else
         {
            if (x >= 0x100) {
               if (x >= 0x1000) {
                  if (x >= 0x4000) {
                     xn = (SqrtTable[x >> 8]     ) + 1;
                  }
                  else
                  {
                     xn = (SqrtTable[x >> 6] >> 1) + 1;
                  }
               }
               else
               {
                  if (x >= 0x400) {
                     xn = (SqrtTable[x >> 4] >> 2) + 1;
                  }
                  else
                  {
                     xn = (SqrtTable[x >> 2] >> 3) + 1;
                  }
               }
            
               return ((xn * xn) > x) ? --xn : xn;
            } 
            else
            {
               if (x >= 0) {
                  return SqrtTable[x] >> 4;
               }
               else
               {
                  return -1; // 
               }
            }
         }
      }
   
// helper function
LOCAL_D inline TInt checkDirection(TPoint aPt1, TPoint aPt2, TPoint aPt3)
	{
	TInt test =  (((aPt2.iX - aPt1.iX)*(aPt3.iY - aPt1.iY)) - ((aPt3.iX - aPt1.iX)*(aPt2.iY - aPt1.iY))); 		
	if(test == 0)
		return 0;
	else
	if(test >1)
		return 1;
	else
		return -1;
	}

TBool MathUtils::Intersect(TPoint l1p1, TPoint l1p2, TPoint l2p1, TPoint l2p2)	
	{
	TInt test1_a, test1_b, test2_a, test2_b;

	test1_a = checkDirection(l1p1, l1p2, l2p1);
	test1_b = checkDirection(l1p1, l1p2, l2p2);
	if (test1_a != test1_b)
		{	
		test2_a = checkDirection(l2p1, l2p2, l1p1);
		test2_b = checkDirection(l2p1, l2p2, l1p2);
		if (test2_a != test2_b)
			{
			return ETrue;
			}
		}
	 return EFalse;
	}