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+--- Thread: Issues with picking (/thread-575.html)
Issues with picking - FFaqui - Nov 21, 2009 04:37 PM
I'm designing a program so that you can color the model by using picking. However, whenever I draw on the model, it appears on the back of the model at strange places. I don't know if I'm doing the ray-triangle intersection correctly. Here is my code:
Code:
bool isViewIntersect(vertex sPos0, vertex sPos1, vertex v0, vertex v1, vertex v2,vertex ¢er)
{
vertex e1,e2,direction,h,s,q;
float a,u,v,intersect;
direction.x=sPos1.x-sPos0.x;
direction.y=sPos1.y-sPos0.y;
direction.z=sPos1.z-sPos0.z;
normalize(direction);
e1.x=v1.x-v0.x;
e1.y=v1.y-v0.y;
e1.z=v1.z-v0.z;
e2.x=v2.x-v0.x;
e2.y=v2.y-v0.y;
e2.z=v2.z-v0.z;
normalize(e1);
normalize(e2);
h.x=direction.y*e2.z-direction.z*e2.y;
h.y=direction.x*e2.z-direction.z*e2.x;
h.z=direction.y*e2.z-direction.z*e2.y;
normalize(h);
a=e1.x*h.x+e1.y*h.y+e1.z*h.z;
if(a>-0.00001 && a<0.00001)
return false;
s.x=sPos0.x-v0.x;
s.y=sPos0.y-v0.y;
s.z=sPos0.z-v0.z;
normalize(s);
u=(s.x*h.x+s.y*h.y+s.z*h.z)/a;
if(u<0.0 || u>1.0)
return false;
q.x=s.y*e1.z-s.z*e1.y;
q.y=s.x*e1.z-s.z*e1.x;
q.z=s.x*e1.y-s.y*e1.x;
normalize(q);
v=(direction.x*q.x+direction.y*q.y+direction.z*q.z)/a;
if(v <0.0 || u+v>1.0)
return false;
intersect=(e2.x*q.x+e2.y*q.y+e2.z*q.z)/a;
if(intersect>0.00001)
{
center.x=sPos0.x+intersect*direction.x;
center.y=sPos0.y+intersect*direction.y;
center.z=sPos0.z+intersect*direction.z;
cout << center.x << " " << center.y << " " << center.z << endl;
return true;
}
return false;
}Please help! Thank you!