/********************************************************/

/* AABB-triangle overlap test code                      */

/* by Tomas Akenine-Möller                              */

/* Function: int triBoxOverlap(float boxcenter[3],      */

/*          float boxhalfsize[3],float triverts[3][3]); */

/* History:                                             */

/*   2001-03-05: released the code in its first version */

/*   2001-06-18: changed the order of the tests, faster */

/*                                                      */

/* Acknowledgement: Many thanks to Pierre Terdiman for  */

/* suggestions and discussions on how to optimize code. */

/* Thanks to David Hunt for finding a ">="-bug!         */

/********************************************************/

#include <math.h>

#include <stdio.h>

#include "triboxCollision.h"



#define X 0

#define Y 1

#define Z 2



#define CROSS(dest,v1,v2) \
		dest[0]=v1[1]*v2[2]-v1[2]*v2[1]; \
		dest[1]=v1[2]*v2[0]-v1[0]*v2[2]; \
		dest[2]=v1[0]*v2[1]-v1[1]*v2[0]; 



#define DOT(v1,v2) (v1[0]*v2[0]+v1[1]*v2[1]+v1[2]*v2[2])



#define SUB(dest,v1,v2) \
	dest[0]=v1[0]-v2[0]; \
	dest[1]=v1[1]-v2[1]; \
	dest[2]=v1[2]-v2[2]; 



#define FINDMINMAX(x0,x1,x2,min,max) \
	min = max = x0;   \
	if(x1<min) min=x1;\
	if(x1>max) max=x1;\
	if(x2<min) min=x2;\
	if(x2>max) max=x2;



int planeBoxOverlap(double normal[3], double vert[3], double maxbox[3])	// -NJMP-

{

  int q;

  double vmin[3],vmax[3],v;

  for(q=X;q<=Z;q++)

  {

    v=vert[q];					// -NJMP-

    if(normal[q]>0.0f)

    {

      vmin[q]=-maxbox[q] - v;	// -NJMP-

      vmax[q]= maxbox[q] - v;	// -NJMP-

    }

    else

    {

      vmin[q]= maxbox[q] - v;	// -NJMP-

      vmax[q]=-maxbox[q] - v;	// -NJMP-

    }

  }

  if(DOT(normal,vmin)>0.0f) return 0;	// -NJMP-

  if(DOT(normal,vmax)>=0.0f) return 1;	// -NJMP-

  

  return 0;

}





/*======================== X-tests ========================*/

#define AXISTEST_X01(a, b, fa, fb)			   \
	p0 = a*v0[Y] - b*v0[Z];			       	   \
	p2 = a*v2[Y] - b*v2[Z];			       	   \
	if(p0<p2) {min=p0; max=p2;} else {min=p2; max=p0;} \
	rad = fa * boxhalfsize[Y] + fb * boxhalfsize[Z];   \
	if(min>rad || max<-rad) return 0;



#define AXISTEST_X2(a, b, fa, fb)			   \
	p0 = a*v0[Y] - b*v0[Z];			           \
	p1 = a*v1[Y] - b*v1[Z];			       	   \
	if(p0<p1) {min=p0; max=p1;} else {min=p1; max=p0;} \
	rad = fa * boxhalfsize[Y] + fb * boxhalfsize[Z];   \
	if(min>rad || max<-rad) return 0;



/*======================== Y-tests ========================*/

#define AXISTEST_Y02(a, b, fa, fb)			   \
	p0 = -a*v0[X] + b*v0[Z];		      	   \
	p2 = -a*v2[X] + b*v2[Z];	       	       	   \
	if(p0<p2) {min=p0; max=p2;} else {min=p2; max=p0;} \
	rad = fa * boxhalfsize[X] + fb * boxhalfsize[Z];   \
	if(min>rad || max<-rad) return 0;



#define AXISTEST_Y1(a, b, fa, fb)			   \
	p0 = -a*v0[X] + b*v0[Z];		      	   \
	p1 = -a*v1[X] + b*v1[Z];	     	       	   \
	if(p0<p1) {min=p0; max=p1;} else {min=p1; max=p0;} \
	rad = fa * boxhalfsize[X] + fb * boxhalfsize[Z];   \
	if(min>rad || max<-rad) return 0;



/*======================== Z-tests ========================*/



#define AXISTEST_Z12(a, b, fa, fb)			   \
	p1 = a*v1[X] - b*v1[Y];			           \
	p2 = a*v2[X] - b*v2[Y];			       	   \
	if(p2<p1) {min=p2; max=p1;} else {min=p1; max=p2;} \
	rad = fa * boxhalfsize[X] + fb * boxhalfsize[Y];   \
	if(min>rad || max<-rad) return 0;



#define AXISTEST_Z0(a, b, fa, fb)			   \
	p0 = a*v0[X] - b*v0[Y];				   \
	p1 = a*v1[X] - b*v1[Y];			           \
	if(p0<p1) {min=p0; max=p1;} else {min=p1; max=p0;} \
	rad = fa * boxhalfsize[X] + fb * boxhalfsize[Y];   \
	if(min>rad || max<-rad) return 0;



int triBoxOverlap(double boxcenter[3],double boxhalfsize[3],double triverts[3][3])

{

  /*    use separating axis theorem to test overlap between triangle and box */
  /*    need to test for overlap in these directions: */
  /*    1) the {x,y,z}-directions (actually, since we use the AABB of the triangle */
  /*       we do not even need to test these) *
  /*    2) normal of the triangle */
  /*    3) crossproduct(edge from tri, {x,y,z}-directin) */
  /*       this gives 3x3=9 more tests */

   double v0[3],v1[3],v2[3];

//   float axis[3];

   double min,max,p0,p1,p2,rad,fex,fey,fez;		// -NJMP- "d" local variable removed

   double normal[3],e0[3],e1[3],e2[3];



   /* This is the fastest branch on Sun */

   /* move everything so that the boxcenter is in (0,0,0) */

   SUB(v0,triverts[0],boxcenter);

   SUB(v1,triverts[1],boxcenter);

   SUB(v2,triverts[2],boxcenter);



   /* compute triangle edges */

   SUB(e0,v1,v0);      /* tri edge 0 */

   SUB(e1,v2,v1);      /* tri edge 1 */

   SUB(e2,v0,v2);      /* tri edge 2 */



   /* Bullet 3:  */

   /*  test the 9 tests first (this was faster) */

   fex = fabs(e0[X]);

   fey = fabs(e0[Y]);

   fez = fabs(e0[Z]);

   AXISTEST_X01(e0[Z], e0[Y], fez, fey);

   AXISTEST_Y02(e0[Z], e0[X], fez, fex);

   AXISTEST_Z12(e0[Y], e0[X], fey, fex);



   fex = fabs(e1[X]);

   fey = fabs(e1[Y]);

   fez = fabs(e1[Z]);

   AXISTEST_X01(e1[Z], e1[Y], fez, fey);

   AXISTEST_Y02(e1[Z], e1[X], fez, fex);

   AXISTEST_Z0(e1[Y], e1[X], fey, fex);



   fex = fabs(e2[X]);

   fey = fabs(e2[Y]);

   fez = fabs(e2[Z]);

   AXISTEST_X2(e2[Z], e2[Y], fez, fey);

   AXISTEST_Y1(e2[Z], e2[X], fez, fex);

   AXISTEST_Z12(e2[Y], e2[X], fey, fex);



   /* Bullet 1: */

   /*  first test overlap in the {x,y,z}-directions */

   /*  find min, max of the triangle each direction, and test for overlap in */

   /*  that direction -- this is equivalent to testing a minimal AABB around */

   /*  the triangle against the AABB */



   /* test in X-direction */

   FINDMINMAX(v0[X],v1[X],v2[X],min,max);

   if(min>boxhalfsize[X] || max<-boxhalfsize[X]) return 0;



   /* test in Y-direction */

   FINDMINMAX(v0[Y],v1[Y],v2[Y],min,max);

   if(min>boxhalfsize[Y] || max<-boxhalfsize[Y]) return 0;



   /* test in Z-direction */

   FINDMINMAX(v0[Z],v1[Z],v2[Z],min,max);

   if(min>boxhalfsize[Z] || max<-boxhalfsize[Z]) return 0;



   /* Bullet 2: */

   /*  test if the box intersects the plane of the triangle */

   /*  compute plane equation of triangle: normal*x+d=0 */

   CROSS(normal,e0,e1);

   // -NJMP- (line removed here)

   if(!planeBoxOverlap(normal,v0,boxhalfsize)) return 0;	// -NJMP-



   return 1;   /* box and triangle overlaps */

}



