// Intersect ray r with the triangle abc. If it hits returns true,
// and puts the t parameter, barycentric coordinates, normal, object id,
// and object material in the isect object
bool TrimeshFace::intersectLocal( const ray& r, isect& i ) const
{
const Vec3d& a = parent->vertices[ids[0]];
const Vec3d& b = parent->vertices[ids[1]];
const Vec3d& c = parent->vertices[ids[2]];
// tangent vectors
Vec3d t1 = b - a;
Vec3d t2 = c - a;
Vec3d n = crossProd(t1,t2);
double D = -n*a;
// if the surface is parallel to the ray there is no intersection
if(r.getDirection()*n == 0)
{
return false;
}
double t = -(n*r.getPosition() + D)/(n*r.getDirection() );
if (t <= RAY_EPSILON)
return false;
// point of intersection with the same plane (doesn't mean intersection with triangle) p(t)=p+t*d
Vec3d p = r.at(t);
// triangle area
double A = n.length()/2.0;
// barycentric coords
double wa = crossProd(c-b, p-b).length() / (2.0*A);
double wb = crossProd(a-c, p-c).length() / (2.0*A);
double wc = crossProd(b-a, p-a).length() / (2.0*A);
if((wa >= 0.0) && (wb >= 0.0) && (wc >= 0.0) && (wa+wb+wc-1.0 <= 0.00001)) {
i.setT(t);
i.setBary(wa, wb, wc);
if (parent->normals.size() == 0) {
i.setN(n);
} else {
Vec3d inter_n = wa*parent->normals[ids[0]] + wb*parent->normals[ids[1]]
+ wc*parent->normals[ids[2]];
inter_n.normalize();
i.setN(inter_n);
}
i.setObject(this);
if (parent->materials.size() == 0) {
i.setMaterial(this->getMaterial() );
} else {
Material inter_m = wa*(*parent->materials[ids[0]]);
inter_m += wb*(*parent->materials[ids[1]]);
inter_m += wc*(*parent->materials[ids[2]]);
i.setMaterial(inter_m);
}
return true;
}
return false;
}
bool Box::intersectLocal( const ray& r, isect& i ) const
{
Vec3d p = r.getPosition();
Vec3d d = r.getDirection();
int it;
double x, y, t, bestT;
int mod0, mod1, mod2, bestIndex;
bestT = HUGE_DOUBLE;
bestIndex = -1;
for(it=0; it<6; it++){
mod0 = it%3;
if(d[mod0] == 0){
continue;
}
t = ((it/3) - 0.5 - p[mod0]) / d[mod0];
if(t < RAY_EPSILON || t > bestT){
continue;
}
mod1 = (it+1)%3;
mod2 = (it+2)%3;
x = p[mod1]+t*d[mod1];
y = p[mod2]+t*d[mod2];
if( x<=0.5 && x>=-0.5 &&
y<=0.5 && y>=-0.5)
{
if(bestT > t){
bestT = t;
bestIndex = it;
}
}
}
if(bestIndex < 0) return false;
i.setT(bestT);
i.setObject(this);
Vec3d intersect_point = r.at(i.t);
int i1 = (bestIndex + 1) % 3;
int i2 = (bestIndex + 2) % 3;
if(bestIndex < 3)
{
i.setN(Vec3d(-double(bestIndex == 0), -double(bestIndex == 1), -double(bestIndex == 2)));
i.setUVCoordinates( Vec2d( 0.5 - intersect_point[ min(i1, i2) ],
0.5 + intersect_point[ max(i1, i2) ] ) );
}
else
{
i.setN(Vec3d(double(bestIndex==3), double(bestIndex == 4), double(bestIndex == 5)));
i.setUVCoordinates( Vec2d( 0.5 + intersect_point[ min(i1, i2) ],
0.5 + intersect_point[ max(i1, i2) ] ) );
}
return true;
}