Moderators… If you are reading this, could you please delete this older post of mine? I am asking another question that is similar, but worded better with better examples of my problem and I don’t want to confuse anyone who may be able to help. Thanks…

I have spent all day trying to figure this out and I feel like I am about 90% there. I have made a screencast video of my problem. It is in MP4 format. If you are interested, you can download/view it by clicking here.

ETA: here is another video of the object rotating. It shows more of the problem.

I am using this Matrix and Vector classes found here.

This is sloppy, sloppy code, I know – But, I am just trying to get this to work before I start organizing it so I know how to organize it.

Please watch the video above to better understand what I am trying to do…

```
void CPCSView::OnLButtonDown(UINT nFlags, CPoint point){
Vector3 vecRayNear,vecRayFar;
{ // find the ray based on click point
//GLdouble dblMatMV[16];
GLdouble dlbMatPM[16];
GLint nArrViewPort[4];
//glGetDoublev(GL_MODELVIEW_MATRIX,dblMatMV); // don't need this, it's stored in m_matModelView
glGetDoublev(GL_PROJECTION_MATRIX, dlbMatPM);
glGetIntegerv(GL_VIEWPORT, nArrViewPort);
double dblArrNear[3];
gluUnProject(point.x, point.y, 0.0, m_matModelView.getTransposed(), dlbMatPM,
nArrViewPort, &dblArrNear[0], &dblArrNear[1],&dblArrNear[2]);
vecRayNear = Vector3((float)dblArrNear[0],(float)dblArrNear[1],(float)dblArrNear[2]);
double dblArrFar[3];
gluUnProject(point.x, point.y, 1.0, m_matModelView.getTransposed(), dlbMatPM,
nArrViewPort, &dblArrFar[0], &dblArrFar[1],&dblArrFar[2]);
vecRayFar = Vector3((float)dblArrFar[0],(float)dblArrFar[1],(float)dblArrFar[2]);
}
// calculate the triangle points and normal
Vector3 vecTri[3];
Vector3 vecNormal;
{
// original triangle
//glVertex3f(1, 0, 0);
//glVertex3f(0, 1, 0);
//glVertex3f(0, 0, 2);
const Matrix4 mvT(m_matModelView);
vecTri[0] = Vector3(1,0,0)*mvT;
vecTri[1] = Vector3(0,1,0)*mvT;
vecTri[2] = Vector3(0,0,2)*mvT;
vecNormal = (vecTri[1]-vecTri[0]).cross(vecTri[2]-vecTri[0]);
vecNormal.normalize();
}
{ // this is normal "where does a line (in this case the ray) intersect a triangle" code
const float flDist1 = (vecRayNear-vecTri[0]).dot(vecNormal);
const float flDist2 = (vecRayFar-vecTri[0]).dot(vecNormal);
if((flDist1 * flDist2) >= 0.0f){
TRACE0("line doesn't cross the triangle.
");
}
if(flDist1 == flDist2){
TRACE0("line and plane are parallel.
");
}
const Vector3 vecIntersect = vecRayNear+(vecRayFar-vecRayNear)*(-flDist1/(flDist2-flDist1));
bool bFoundIntersection = true;
Vector3 vecTest;
vecTest = vecNormal.cross(vecTri[1]-vecTri[0]);
if(vecTest.dot(vecIntersect-vecTri[0])<0.0f){
TRACE0("No intersection 1
");
bFoundIntersection = false;
}
vecTest = vecNormal.cross(vecTri[2]-vecTri[1]);
if(vecTest.dot(vecIntersect-vecTri[1])<0.0f){
TRACE0("No intersection 2
");
bFoundIntersection = false;
}
vecTest = vecNormal.cross(vecTri[0]-vecTri[2]);
if(vecTest.dot(vecIntersect-vecTri[0])<0.0f){
TRACE0("No intersection 3
");
bFoundIntersection = false;
}
if(bFoundIntersection){
m_vecClicks.push_back(vecIntersect);
TRACE3("Found Hit: %g; %g; %g
",vecIntersect.x,vecIntersect.y,vecIntersect.z);
Repaint();
}
}
CGLEnabledView::OnLButtonDown(nFlags, point);
}
```

Any insight would be greatly appreciated!