bool CPolygon::Intersect(CRay &ray, bool cull, float *dist)
{
if(!ray.Intersect(m_vertexList[0], m_vertexList[1],
m_vertexList[2], false, dist)) return false;
if(!cull)
{
if(!ray.Intersect(m_vertexList[2], m_vertexList[1],
m_vertexList[0], false, dist)) return false;
}
return true;
}
void CPolygon::Clip(CPlane &pl, CPolygon *front, CPolygon *back)
{
CVector3 frontVecs[3], backVecs[3];
int frontIndex = 0;
int backIndex = 0;
if(!front && !back) return;
switch(pl.ClassifyPoint(m_vertexList[0]))
{
case UGP_FRONT:
frontVecs[frontIndex++] = m_vertexList[0];
break;
case UGP_BACK:
backVecs[backIndex++] = m_vertexList[0];
break;
case UGP_ON_PLANE:
frontVecs[frontIndex++] = m_vertexList[0];
backVecs[backIndex++] = m_vertexList[0];
//frontVecs[backIndex++] = m_vertexList[0];
break;
default:
return;
}
int index = 0;
int v1Type = 0, v2Type = 0;
CVector3 v1, v2, intersectPoint;
CRay ray;
for(int i = 1; i < 4; i++)
{
if(i == 3) index = 0;
else index = i;
v1 = m_vertexList[i - 1];
v2 = m_vertexList[index];
v1Type = pl.ClassifyPoint(v1);
v2Type = pl.ClassifyPoint(v2);
if(v2Type == UGP_ON_PLANE)
{
frontVecs[frontIndex++] = m_vertexList[index];
backVecs[backIndex++] = m_vertexList[index];
}
else
{
float length = 0;
ray.m_origin = v1;
ray.m_direction = v2 - v1;
length = ray.m_direction.GetLength();
ray.m_direction.Normal();
if(ray.Intersect(pl, false, length, &intersectPoint, 0) &&
(v1Type != UGP_ON_PLANE))
{
frontVecs[frontIndex++] = intersectPoint;
backVecs[backIndex++] = intersectPoint;
}
if(index == 0) continue;
if(v2Type == UGP_FRONT) frontVecs[frontIndex++] = m_vertexList[index];
else if(v2Type == UGP_BACK) backVecs[backIndex++] = m_vertexList[index];
}
}
if(front)
{
CPlane fPl;
CVector3 n, n2;
// Be sure to keep same orientation.
fPl.CreatePlaneFromTri(frontVecs[0], frontVecs[1], frontVecs[2]);
n.x = fPl.a; n.y = fPl.b; n.z = fPl.c;
n2.x = pl.a; n2.y = pl.b; n2.z = pl.c;
if(n.DotProduct3(n2) >= 0.0f)
{
front->m_vertexList[0] = frontVecs[0];
front->m_vertexList[1] = frontVecs[1];
front->m_vertexList[2] = frontVecs[2];
}
else
{
front->m_vertexList[0] = frontVecs[2];
front->m_vertexList[1] = frontVecs[1];
front->m_vertexList[2] = frontVecs[0];
}
}
if(back)
{
CPlane fPl;
CVector3 n, n2;
// Be sure to keep same orientation.
fPl.CreatePlaneFromTri(backVecs[0], backVecs[1], backVecs[2]);
n.x = fPl.a; n.y = fPl.b; n.z = fPl.c;
n2.x = pl.a; n2.y = pl.b; n2.z = pl.c;
if(n.DotProduct3(n2) >= 0.0f)
{
back->m_vertexList[0] = backVecs[0];
back->m_vertexList[1] = backVecs[1];
back->m_vertexList[2] = backVecs[2];
}
else
{
back->m_vertexList[0] = backVecs[2];
back->m_vertexList[1] = backVecs[1];
back->m_vertexList[2] = backVecs[0];
}
}
}