// culling
// TODO: work out how it works on the real thing
// the normalization part is a wild guess

Vertex *v0, *v1, *v2, *v3;
s64 normalX, normalY, normalZ;
s64 dot;

v0 = &TempVertexBuffer[0];
v1 = &TempVertexBuffer[1];
v2 = &TempVertexBuffer[2];
v3 = &TempVertexBuffer[3];

normalX = ((s64)(v0->Position[1]-v1->Position[1]) * (v2->Position[3]-v1->Position[3]))
- ((s64)(v0->Position[3]-v1->Position[3]) * (v2->Position[1]-v1->Position[1]));
normalY = ((s64)(v0->Position[3]-v1->Position[3]) * (v2->Position[0]-v1->Position[0]))
- ((s64)(v0->Position[0]-v1->Position[0]) * (v2->Position[3]-v1->Position[3]));
normalZ = ((s64)(v0->Position[0]-v1->Position[0]) * (v2->Position[1]-v1->Position[1]))
- ((s64)(v0->Position[1]-v1->Position[1]) * (v2->Position[0]-v1->Position[0]));

while ((((normalX>>31) ^ (normalX>>63)) != 0) ||
(((normalY>>31) ^ (normalY>>63)) != 0) ||
(((normalZ>>31) ^ (normalZ>>63)) != 0))
{
normalX >>= 4;
normalY >>= 4;
normalZ >>= 4;
}

dot = ((s64)v1->Position[0] * normalX) + ((s64)v1->Position[1] * normalY) + ((s64)v1->Position[3] * normalZ);

bool facingview = (dot < 0);

if (facingview)
{
if (!(CurPolygonAttr & (1<<7)))
{
LastStripPolygon = NULL;
return;
}
}
else if (dot > 0)
{
if (!(CurPolygonAttr & (1<<6)))
{
LastStripPolygon = NULL;
return;
}
}