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| /********************************************************/
/* 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! */
/* See also: https://doi.org/10.1145/1198555.1198747 */
/* http://fileadmin.cs.lth.se/cs/personal/tomas_akenine-moller/code/ */
/********************************************************/
#include <math.h>
#include <stdio.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(float normal[3], float vert[3], float maxbox[3]) // -NJMP-
{
int q;
float 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(float boxcenter[3],float boxhalfsize[3],float 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 */
float v0[3],v1[3],v2[3];
// float axis[3];
float min,max,p0,p1,p2,rad,fex,fey,fez; // -NJMP- "d" local variable removed
float 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 = fabsf(e0[X]);
fey = fabsf(e0[Y]);
fez = fabsf(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 = fabsf(e1[X]);
fey = fabsf(e1[Y]);
fez = fabsf(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 = fabsf(e2[X]);
fey = fabsf(e2[Y]);
fez = fabsf(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 */
}
bool segBoxOverlap (coord * min, coord * max,
coord * p1, coord * p2)
{
// Find min and max X for the segment
double minX = p1->x;
double maxX = p2->x;
if(p1->x > p2->x)
{
minX = p2->x;
maxX = p1->x;
}
// Find the intersection of the segment's and rectangle's x-projections
if(maxX > max->x)
{
maxX = max->x;
}
if(minX < min->x)
{
minX = min->x;
}
if(minX > maxX) // If their projections do not intersect return false
{
return false;
}
// Find corresponding min and max Y for min and max X we found before
double minY = p1->y;
double maxY = p2->y;
double dx = p2->x - p1->x;
if(fabs(dx) > 0.0000001)
{
double a = (p2->y - p1->y) / dx;
double b = p1->y - a * p1->x;
minY = a * minX + b;
maxY = a * maxX + b;
}
if(minY > maxY)
{
double tmp = maxY;
maxY = minY;
minY = tmp;
}
// Find the intersection of the segment's and rectangle's y-projections
if(maxY > max->y)
{
maxY = max->y;
}
if(minY < min->y)
{
minY = min->y;
}
if(minY > maxY) // If Y-projections do not intersect return false
{
return false;
}
return true;
}
|
