bool Face::triangleDistanceTest(XYZ &v_test,float dist_test)
{
float d;
XYZ t,u,ret;
Vector v;
if (face_normal.x==face_normal.y==face_normal.z==0) calcFaceNormal();
d = planeDistanceTo(v_test);
v = face_normal;
v.makeUnit();
v *= d;
t = v_test;
t -= v;
u = v_test;
bool onTri = segmentIntersects(ret,t,u);
// printf("ont: %d, dist: %f \n",onTri,d);
if (onTri)
{
return (d <= dist_test);
}
else
{
return false;
}
}
int prepareObject(struct OBJ_Model * obj)
{
if (obj==0) { fprintf(stderr,"Cannot Prepare empty object \n"); return 0; }
if (obj->numFaces==0) { fprintf(stderr,"Object has zero faces \n"); return 0; }
if (obj->faceList==0) { fprintf(stderr,"Object has a null face list \n"); return 0; }
if (obj->vertexList==0) { fprintf(stderr,"Object has a null vertex list \n"); return 0; }
long unsigned int i;
Normal tmpnrm;
for(i=0;i<obj->numFaces;i++)
{
calcFaceNormal(&tmpnrm,obj->vertexList[obj->faceList[i].v[0]],obj->vertexList[obj->faceList[i].v[1]],obj->vertexList[obj->faceList[i].v[2]],0);
obj->faceList[i].fc_normal.n1=tmpnrm.n1;
obj->faceList[i].fc_normal.n2=tmpnrm.n2;
obj->faceList[i].fc_normal.n3=tmpnrm.n3;
}
return 1;
}
/* only works with triangles */
bool Face::segmentIntersects(XYZ &returned_intersect_point, XYZ &segment_start, XYZ &segment_end, float tolerance)
{
cvrFloat ang_a,ang_b,ang_c;
cvrFloat denom,mu,d;
Vector pa,pb,pc;
calcFaceNormal();
d = - face_normal.x * points[0]->x - face_normal.y * points[0]->y - face_normal.z * points[0]->z;
/* calculate position where the plane intersects the segment */
denom = face_normal.x * (segment_end.x - segment_start.x) + face_normal.y * (segment_end.y - segment_start.y) + face_normal.z * (segment_end.z - segment_start.z);
if (fabs(denom) < FLOAT_TOLERANCE) return false; /* point on plane is outside of line, no intersection */
mu = - (d + face_normal.x * segment_start.x + face_normal.y * segment_start.y + face_normal.z * segment_start.z) / denom;
returned_intersect_point = XYZ(
(float)(segment_start.x + mu * (segment_end.x - segment_start.x)),
(float)(segment_start.y + mu * (segment_end.y - segment_start.y)),
(float)(segment_start.z + mu * (segment_end.z - segment_start.z))
);
if (mu < 0 || mu > 1) return false;
pa = returned_intersect_point - *points[0];
pb = returned_intersect_point - *points[1];
pc = returned_intersect_point - *points[2];
pa.makeUnit(); pb.makeUnit(); pc.makeUnit();
ang_a = pa.x*pb.x + pa.y*pb.y + pa.z*pb.z;
ang_b = pb.x*pc.x + pb.y*pc.y + pb.z*pc.z;
ang_c = pc.x*pa.x + pc.y*pa.y + pc.z*pa.z;
/* check to see if angles add up to 2*PI, if so the point lies within the triangle */
if (fabs((acos(ang_a) + acos(ang_b) + acos(ang_c)) - M_TWO_PI) > tolerance) return false;
return true;
}
