Poly - Line Intersection....almost there...

Hey guys, please help me out someone and dont bug me because of my lack of math knowledge

. I just cant get polygon line collision to work properly: I''m testing the edges of a triangle against the polys that build up my view frustum. The problem is, when all edges are within the frustum, a collision is still registered. It seems all code i''ve tried so far checks if the endless ray the line describes hits the poly, not the line itself. So I checked with D3DXPlaneIntersectLine() if the edge hits the plane the poly describes, top of the code. And its NOT working! If all lines are inside the frustum the function returns a collision. Is this funtion also only checking the ray against the plane? Well, I''ll post along the code of my current function, I already wasted some nights on this, so please, help me out until I buy my linear algebra book...


MLE_API bool mleLineHitsTriangle2(const D3DXVECTOR3& pvLineA, 
																  const D3DXVECTOR3& pvLineB, 
																  const D3DXVECTOR3& pvTriA, 
																  const D3DXVECTOR3& pvTriB, 
																  const D3DXVECTOR3& pvTriC, 
																  D3DXVECTOR3* pvOut) // =NULL
{
	D3DXVECTOR3 vOut;
	D3DXPLANE		Plane;

	// die ebene des dreiecks berechnen
	D3DXPlaneFromPoints(&Plane, &pvTriA, &pvTriB, &pvTriC);
	
	// wenn sie die ebene nicht schneidet, kann sie das dreieck nicht schneiden
	if (D3DXPlaneIntersectLine(&vOut, &Plane, &pvLineA, &pvLineB) == NULL)
		return false;
	
	
	// der richtungsvektor der linie
	D3DXVECTOR3 vDir = pvLineB - pvLineA;

	// Find vectors for two edges sharing vert0
  D3DXVECTOR3 edge1 = pvTriB - pvTriA;
  D3DXVECTOR3 edge2 = pvTriC - pvTriA;

	// Begin calculating determinant - also used to calculate U parameter
  D3DXVECTOR3 pvec;
  D3DXVec3Cross(&pvec, &vDir, &edge2);

	// If determinant is near zero, ray lies in plane of triangle
  float det = D3DXVec3Dot(&edge1, &pvec);

	D3DXVECTOR3 tvec;
  if(det > 0)
	{
		tvec = pvLineA - pvTriA;
  }
	else
	{
		tvec = pvTriA - pvLineA;
    det = -det;
  }

	if( det < 0.0001f )
		return false;

  // Calculate U parameter and test bounds
  vOut.x = D3DXVec3Dot(&tvec, &pvec);
  if(vOut.x < 0.0f || vOut.x > det)
		return false;

	// Prepare to test V parameter
  D3DXVECTOR3 qvec;
  D3DXVec3Cross(&qvec, &tvec, &edge1);

	// Calculate V parameter and test bounds
	vOut.y = D3DXVec3Dot(&vDir, &qvec);
  if(vOut.y < 0.0f || vOut.x + vOut.y > det)
		return false;

	// Calculate t, scale parameters, ray intersects triangle
	vOut.z = D3DXVec3Dot(&edge2, &qvec);
  float fInvDet = 1.0f / det;
  vOut.z *= fInvDet;
  vOut.x *= fInvDet;
  vOut.y *= fInvDet;

	if (pvOut != NULL)
		*pvOut = vOut;


	return true;
}

its got mixed german and english comments cause its mainly taken from the DX ''Pick'' sample

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