gts/tribox3.c

   1 /**
   2  * History:
   3  * 2004-10-27 Stephane Popinet: changed float to double
   4  */
   5
   6 /********************************************************/
   7 /* AABB-triangle overlap test code                      */
   8 /* by Tomas Akenine-Möller                              */
   9 /* Function: int triBoxOverlap(float boxcenter[3],      */
  10 /*          float boxhalfsize[3],float triverts[3][3]); */
  11 /* History:                                             */
  12 /*   2001-03-05: released the code in its first version */
  13 /*   2001-06-18: changed the order of the tests, faster */
  14 /*                                                      */
  15 /* Acknowledgement: Many thanks to Pierre Terdiman for  */
  16 /* suggestions and discussions on how to optimize code. */
  17 /* Thanks to David Hunt for finding a ">="-bug!         */
  18 /********************************************************/
  19 #include <math.h>
  20 #include <stdio.h>
  21
  22 #define X 0
  23 #define Y 1
  24 #define Z 2
  25
  26 #define CROSS(dest,v1,v2) \
  27           dest[0]=v1[1]*v2[2]-v1[2]*v2[1]; \
  28           dest[1]=v1[2]*v2[0]-v1[0]*v2[2]; \
  29           dest[2]=v1[0]*v2[1]-v1[1]*v2[0];
  30
  31 #define DOT(v1,v2) (v1[0]*v2[0]+v1[1]*v2[1]+v1[2]*v2[2])
  32
  33 #define SUB(dest,v1,v2) \
  34           dest[0]=v1[0]-v2[0]; \
  35           dest[1]=v1[1]-v2[1]; \
  36           dest[2]=v1[2]-v2[2];
  37
  38 #define FINDMINMAX(x0,x1,x2,min,max) \
  39   min = max = x0;   \
  40   if(x1<min) min=x1;\
  41   if(x1>max) max=x1;\
  42   if(x2<min) min=x2;\
  43   if(x2>max) max=x2;
  44
  45 int planeBoxOverlap(double normal[3], double vert[3], double maxbox[3]) // -NJMP-
  46 {
  47   int q;
  48   double vmin[3],vmax[3],v;
  49   for(q=X;q<=Z;q++)
  50   {
  51     v=vert[q];                                  // -NJMP-
  52     if(normal[q]>0.0f)
  53     {
  54       vmin[q]=-maxbox[q] - v;   // -NJMP-
  55       vmax[q]= maxbox[q] - v;   // -NJMP-
  56     }
  57     else
  58     {
  59       vmin[q]= maxbox[q] - v;   // -NJMP-
  60       vmax[q]=-maxbox[q] - v;   // -NJMP-
  61     }
  62   }
  63   if(DOT(normal,vmin)>0.0f) return 0;   // -NJMP-
  64   if(DOT(normal,vmax)>=0.0f) return 1;  // -NJMP-
  65
  66   return 0;
  67 }
  68
  69
  70 /*======================== X-tests ========================*/
  71 #define AXISTEST_X01(a, b, fa, fb)                         \
  72         p0 = a*v0[Y] - b*v0[Z];                            \
  73         p2 = a*v2[Y] - b*v2[Z];                            \
  74         if(p0<p2) {min=p0; max=p2;} else {min=p2; max=p0;} \
  75         rad = fa * boxhalfsize[Y] + fb * boxhalfsize[Z];   \
  76         if(min>rad || max<-rad) return 0;
  77
  78 #define AXISTEST_X2(a, b, fa, fb)                          \
  79         p0 = a*v0[Y] - b*v0[Z];                            \
  80         p1 = a*v1[Y] - b*v1[Z];                            \
  81         if(p0<p1) {min=p0; max=p1;} else {min=p1; max=p0;} \
  82         rad = fa * boxhalfsize[Y] + fb * boxhalfsize[Z];   \
  83         if(min>rad || max<-rad) return 0;
  84
  85 /*======================== Y-tests ========================*/
  86 #define AXISTEST_Y02(a, b, fa, fb)                         \
  87         p0 = -a*v0[X] + b*v0[Z];                           \
  88         p2 = -a*v2[X] + b*v2[Z];                           \
  89         if(p0<p2) {min=p0; max=p2;} else {min=p2; max=p0;} \
  90         rad = fa * boxhalfsize[X] + fb * boxhalfsize[Z];   \
  91         if(min>rad || max<-rad) return 0;
  92
  93 #define AXISTEST_Y1(a, b, fa, fb)                          \
  94         p0 = -a*v0[X] + b*v0[Z];                           \
  95         p1 = -a*v1[X] + b*v1[Z];                           \
  96         if(p0<p1) {min=p0; max=p1;} else {min=p1; max=p0;} \
  97         rad = fa * boxhalfsize[X] + fb * boxhalfsize[Z];   \
  98         if(min>rad || max<-rad) return 0;
  99
 100 /*======================== Z-tests ========================*/
 101
 102 #define AXISTEST_Z12(a, b, fa, fb)                         \
 103         p1 = a*v1[X] - b*v1[Y];                            \
 104         p2 = a*v2[X] - b*v2[Y];                            \
 105         if(p2<p1) {min=p2; max=p1;} else {min=p1; max=p2;} \
 106         rad = fa * boxhalfsize[X] + fb * boxhalfsize[Y];   \
 107         if(min>rad || max<-rad) return 0;
 108
 109 #define AXISTEST_Z0(a, b, fa, fb)                          \
 110         p0 = a*v0[X] - b*v0[Y];                            \
 111         p1 = a*v1[X] - b*v1[Y];                            \
 112         if(p0<p1) {min=p0; max=p1;} else {min=p1; max=p0;} \
 113         rad = fa * boxhalfsize[X] + fb * boxhalfsize[Y];   \
 114         if(min>rad || max<-rad) return 0;
 115
 116 int triBoxOverlap(double boxcenter[3],double boxhalfsize[3],double triverts[3][3])
 117 {
 118
 119   /*    use separating axis theorem to test overlap between triangle and box */
 120   /*    need to test for overlap in these directions: */
 121   /*    1) the {x,y,z}-directions (actually, since we use the AABB of the triangle */
 122   /*       we do not even need to test these) */
 123   /*    2) normal of the triangle */
 124   /*    3) crossproduct(edge from tri, {x,y,z}-directin) */
 125   /*       this gives 3x3=9 more tests */
 126    double v0[3],v1[3],v2[3];
 127 //   double axis[3];
 128    double min,max,p0,p1,p2,rad,fex,fey,fez;             // -NJMP- "d" local variable removed
 129    double normal[3],e0[3],e1[3],e2[3];
 130
 131    /* This is the fastest branch on Sun */
 132    /* move everything so that the boxcenter is in (0,0,0) */
 133    SUB(v0,triverts[0],boxcenter);
 134    SUB(v1,triverts[1],boxcenter);
 135    SUB(v2,triverts[2],boxcenter);
 136
 137    /* compute triangle edges */
 138    SUB(e0,v1,v0);      /* tri edge 0 */
 139    SUB(e1,v2,v1);      /* tri edge 1 */
 140    SUB(e2,v0,v2);      /* tri edge 2 */
 141
 142    /* Bullet 3:  */
 143    /*  test the 9 tests first (this was faster) */
 144    fex = fabsf(e0[X]);
 145    fey = fabsf(e0[Y]);
 146    fez = fabsf(e0[Z]);
 147    AXISTEST_X01(e0[Z], e0[Y], fez, fey);
 148    AXISTEST_Y02(e0[Z], e0[X], fez, fex);
 149    AXISTEST_Z12(e0[Y], e0[X], fey, fex);
 150
 151    fex = fabsf(e1[X]);
 152    fey = fabsf(e1[Y]);
 153    fez = fabsf(e1[Z]);
 154    AXISTEST_X01(e1[Z], e1[Y], fez, fey);
 155    AXISTEST_Y02(e1[Z], e1[X], fez, fex);
 156    AXISTEST_Z0(e1[Y], e1[X], fey, fex);
 157
 158    fex = fabsf(e2[X]);
 159    fey = fabsf(e2[Y]);
 160    fez = fabsf(e2[Z]);
 161    AXISTEST_X2(e2[Z], e2[Y], fez, fey);
 162    AXISTEST_Y1(e2[Z], e2[X], fez, fex);
 163    AXISTEST_Z12(e2[Y], e2[X], fey, fex);
 164
 165    /* Bullet 1: */
 166    /*  first test overlap in the {x,y,z}-directions */
 167    /*  find min, max of the triangle each direction, and test for overlap in */
 168    /*  that direction -- this is equivalent to testing a minimal AABB around */
 169    /*  the triangle against the AABB */
 170
 171    /* test in X-direction */
 172    FINDMINMAX(v0[X],v1[X],v2[X],min,max);
 173    if(min>boxhalfsize[X] || max<-boxhalfsize[X]) return 0;
 174
 175    /* test in Y-direction */
 176    FINDMINMAX(v0[Y],v1[Y],v2[Y],min,max);
 177    if(min>boxhalfsize[Y] || max<-boxhalfsize[Y]) return 0;
 178
 179    /* test in Z-direction */
 180    FINDMINMAX(v0[Z],v1[Z],v2[Z],min,max);
 181    if(min>boxhalfsize[Z] || max<-boxhalfsize[Z]) return 0;
 182
 183    /* Bullet 2: */
 184    /*  test if the box intersects the plane of the triangle */
 185    /*  compute plane equation of triangle: normal*x+d=0 */
 186    CROSS(normal,e0,e1);
 187    // -NJMP- (line removed here)
 188    if(!planeBoxOverlap(normal,v0,boxhalfsize)) return 0;        // -NJMP-
 189
 190    return 1;   /* box and triangle overlaps */
 191 }
 192