static __regargs UWORD ClipPolygon(Point3D *S, Point3D *O,
UWORD n, UWORD plane)
{
Point3D *E = S + 1;
BOOL S_inside = CheckInside(S, plane);
BOOL needClose = TRUE;
UWORD m = 0;
if (S_inside) {
needClose = FALSE;
O[m++] = *S;
}
while (--n) {
BOOL E_inside = CheckInside(E, plane);
if (S_inside && E_inside) {
O[m++] = *E;
} else if (S_inside && !E_inside) {
ClipEdge(&O[m++], S, E, plane);
} else if (!S_inside && E_inside) {
ClipEdge(&O[m++], E, S, plane);
O[m++] = *E;
}
S_inside = E_inside;
S++; E++;
}
if (needClose)
O[m++] = *O;
return m;
}
void ClipPolygon(float_polygon_type poly, float_polygon_type &poly_out)
{
win_edge_type edge;
for (int edg = 0; edg < 4; edg++)
{
poly_out.n = 0; // Reset poly_out
edge = (win_edge_type)edg;
poly.vertex[poly.n] = poly.vertex[0];
for (int i = 0; i < poly.n; i++)
ClipEdge(poly.vertex[i], poly.vertex[i + 1], edge, poly_out);
poly = poly_out;// Copy poly_out to poly
}
}
void TriangleClipperBase::processFaces()
{
for (UINT32 i = 0; i < (UINT32)mesh.faces.size(); i++)
{
ClipFace& face = mesh.faces[i];
if (face.visible)
{
// The edge is culled. If the edge is exactly on the clip
// plane, it is possible that a visible triangle shares it.
// The edge will be re-added during the face loop.
for (UINT32 j = 0; j < (UINT32)face.edges.size(); j++)
{
ClipEdge& edge = mesh.edges[face.edges[j]];
ClipVert& v0 = mesh.verts[edge.verts[0]];
ClipVert& v1 = mesh.verts[edge.verts[1]];
v0.occurs = 0;
v1.occurs = 0;
}
}
UINT32 start, end;
if (getOpenPolyline(mesh.faces[i], start, end))
{
// Polyline is open, close it
UINT32 closeEdgeIdx = (UINT32)mesh.edges.size();
mesh.edges.push_back(ClipEdge());
ClipEdge& closeEdge = mesh.edges.back();
closeEdge.verts[0] = start;
closeEdge.verts[1] = end;
closeEdge.faces.push_back(i);
face.edges.push_back(closeEdgeIdx);
}
}
}
void OcclusionBuffer::ClipVertices(const Vector4& plane, Vector4* vertices, bool* triangles, unsigned& numTriangles)
{
unsigned num = numTriangles;
for (unsigned i = 0; i < num; ++i)
{
if (triangles[i])
{
unsigned index = i * 3;
float d0 = plane.DotProduct(vertices[index]);
float d1 = plane.DotProduct(vertices[index + 1]);
float d2 = plane.DotProduct(vertices[index + 2]);
// If all vertices behind the plane, reject triangle
if (d0 < 0.0f && d1 < 0.0f && d2 < 0.0f)
{
triangles[i] = false;
continue;
}
// If 2 vertices behind the plane, create a new triangle in-place
else if (d0 < 0.0f && d1 < 0.0f)
{
vertices[index] = ClipEdge(vertices[index], vertices[index + 2], d0, d2);
vertices[index + 1] = ClipEdge(vertices[index + 1], vertices[index + 2], d1, d2);
}
else if (d0 < 0.0f && d2 < 0.0f)
{
vertices[index] = ClipEdge(vertices[index], vertices[index + 1], d0, d1);
vertices[index + 2] = ClipEdge(vertices[index + 2], vertices[index + 1], d2, d1);
}
else if (d1 < 0.0f && d2 < 0.0f)
{
vertices[index + 1] = ClipEdge(vertices[index + 1], vertices[index], d1, d0);
vertices[index + 2] = ClipEdge(vertices[index + 2], vertices[index], d2, d0);
}
// 1 vertex behind the plane: create one new triangle, and modify one in-place
else if (d0 < 0.0f)
{
unsigned newIdx = numTriangles * 3;
triangles[numTriangles] = true;
++numTriangles;
vertices[newIdx] = ClipEdge(vertices[index], vertices[index + 2], d0, d2);
vertices[newIdx + 1] = vertices[index] = ClipEdge(vertices[index], vertices[index + 1], d0, d1);
vertices[newIdx + 2] = vertices[index + 2];
}
else if (d1 < 0.0f)
{
unsigned newIdx = numTriangles * 3;
triangles[numTriangles] = true;
++numTriangles;
vertices[newIdx + 1] = ClipEdge(vertices[index + 1], vertices[index], d1, d0);
vertices[newIdx + 2] = vertices[index + 1] = ClipEdge(vertices[index + 1], vertices[index + 2], d1, d2);
vertices[newIdx] = vertices[index];
}
else if (d2 < 0.0f)
{
unsigned newIdx = numTriangles * 3;
triangles[numTriangles] = true;
++numTriangles;
vertices[newIdx + 2] = ClipEdge(vertices[index + 2], vertices[index + 1], d2, d1);
vertices[newIdx] = vertices[index + 2] = ClipEdge(vertices[index + 2], vertices[index], d2, d0);
vertices[newIdx + 1] = vertices[index + 1];
}
}
}
}
