public double Area()
{
RHVector3 d1 = vertices[1].pos.Subtract(vertices[0].pos);
RHVector3 d2 = vertices[2].pos.Subtract(vertices[1].pos);
return(0.5 * d1.CrossProduct(d2).Length);
}
public void RecomputeNormal()
{
try
{
RHVector3 d1 = vertices[1].pos.Subtract(vertices[0].pos);
RHVector3 d2 = vertices[2].pos.Subtract(vertices[1].pos);
normal = d1.CrossProduct(d2);
normal.NormalizeSafe();
}
catch (System.NullReferenceException)
{ }
}
public double alphaBeta; // Sum of dihedral angles to a virtual shared triangle
public TopoEdgePair(TopoEdge _edgeA, TopoEdge _edgeB)
{
edgeA = _edgeA;
edgeB = _edgeB;
RHVector3 sharedPoint = null;
RHVector3 p1 = null, p2 = null;
if (edgeA.v1 == edgeB.v1)
{
sharedPoint = edgeA.v1.pos;
p1 = edgeA.v2.pos;
p2 = edgeB.v2.pos;
}
else if (edgeA.v1 == edgeB.v2)
{
sharedPoint = edgeA.v1.pos;
p1 = edgeA.v2.pos;
p2 = edgeB.v1.pos;
}
else if (edgeA.v2 == edgeB.v1)
{
sharedPoint = edgeA.v1.pos;
p1 = edgeA.v1.pos;
p2 = edgeB.v2.pos;
}
else if (edgeA.v2 == edgeB.v2)
{
sharedPoint = edgeA.v2.pos;
p1 = edgeA.v1.pos;
p2 = edgeB.v1.pos;
}
RHVector3 d1 = p1.Subtract(sharedPoint);
RHVector3 d2 = p2.Subtract(sharedPoint);
RHVector3 normal = d1.CrossProduct(d2);
normal.NormalizeSafe();
//alphaBeta = normal.AngleForNormalizedVectors(edgeA.faces.First.Value.normal) + normal.AngleForNormalizedVectors(edgeB.faces.First.Value.normal);
//if (alphaBeta > Math.PI) // normal was wrong direction
//alphaBeta = 2 * Math.PI - alphaBeta;
}
//--- MODEL_SLA // milton
// 實作論文的方法 - Fast, Minimum Storage RayTriangle Intersection
// t => delta, 如果有打到物體,t>0,否則t<0
public bool IntersectsLineTest(RHVector3 orig, RHVector3 dir, out double t, out double u, out double v)
{
t = u = v = 0;
//Debug.WriteLine("IntersectsLine orig " + orig + " dir " + dir );
//Debug.WriteLine("IntersectsLine ver1 " + vertices[0].pos + " ver2 " + vertices[1].pos + " ver3 " + vertices[2].pos);
RHVector3 vert0 = vertices[0].pos;
/* find vectors for two edges sharing vert0
* SUB(edge1, vert1, vert0)
* SUB(edge2, vert2, vert0) */
RHVector3 edge1 = vertices[1].pos.Subtract(vert0);
RHVector3 edge2 = vertices[2].pos.Subtract(vert0);
/* begin calculating determinant - also used to calculate U parameter
* CROSS(pvec, dir, edge2)*/
RHVector3 pvec = dir.CrossProduct(edge2);
/* if determinant is near zero, ray lies in plane of triangle
* det = DOT(edge1, pvec)*/
double det = edge1.ScalarProduct(pvec);
//Debug.WriteLine("IntersectsLine det " + det);
/* define TEST_CULL if culling is desired
* if (det < EPSILON)return 0*/
if (det < 0.000001)
{
return(false);
}
/* calculate distance from vert0 to ray origin
* SUB(tvec, orig, vert0)*/
RHVector3 tvec = orig.Subtract(vert0);
//Debug.WriteLine("IntersectsLine tvec " + tvec);
/* calculate U parameter and test bounds
* u = DOT(tvec, pvec)*/
u = tvec.ScalarProduct(pvec);
/*if (*u < 0.0 || *u > det) return 0;*/
//Debug.WriteLine("IntersectsLine u " + u);
if (u < 0 || u > det)
{
return(false);
}
/* prepare to test V parameter
* CROSS(qvec, tvec, edge1)*/
RHVector3 qvec = tvec.CrossProduct(edge1);
/* calculate V parameter and test bounds
* v = DOT(dir, qvec)*/
v = dir.ScalarProduct(qvec);
//Debug.WriteLine("IntersectsLine v " + v);
/*if (*v < 0.0 || *u + *v > det) return 0*/
if (v < 0 || (u + v) > det)
{
return(false);
}
/* calculate t, scale parameters, ray intersects triangle
* t = DOT(edge2, qvec)
* inv_det = 1.0 / det
* t *= inv_det
* u *= inv_det
* v *= inv_det*/
double inv_det = 1.0 / det;
t = edge2.ScalarProduct(qvec);
t *= inv_det;
u *= inv_det;
v *= inv_det;
return(true);
}