public void ClipSubMesh(RDBoundingBox boundingBox, int subMeshNumber)
{
clippedVerticesRD = new List <Vector3RD>();
if (subMeshNumber >= mesh.subMeshCount)
{
return;
}
int[] indices = mesh.GetIndices(subMeshNumber);
temporaryOrigin = new Vector3RD(boundingBox.minX, boundingBox.minY, 0);
Vector3 point1;
Vector3 point2;
Vector3 point3;
List <Vector3> clippingPolygon = CreateClippingPolygon(boundingBox);
List <Vector3> clippingVectorList = new List <Vector3>();
clippingVectorList.Capacity = 3;
for (int i = 0; i < indices.Length; i += 3)
{
point1 = OffsetRDVertex(rdVertices[indices[i]], temporaryOrigin);
point2 = OffsetRDVertex(rdVertices[indices[i + 1]], temporaryOrigin);
point3 = OffsetRDVertex(rdVertices[indices[i + 2]], temporaryOrigin);
trianglePosition position = GetTrianglePosition(point1, point2, point3, boundingBox);
if (position == trianglePosition.inside)
{
clippedVerticesRD.Add(RestoreRDVertex(point1, temporaryOrigin));
clippedVerticesRD.Add(RestoreRDVertex(point2, temporaryOrigin));
clippedVerticesRD.Add(RestoreRDVertex(point3, temporaryOrigin));
}
else if (position == trianglePosition.overlap)
{
clippingVectorList.Clear();
clippingVectorList.Add(point1);
clippingVectorList.Add(point2);
clippingVectorList.Add(point3);
List <Vector3> clippedTriangle = Netherlands3D.Utilities.TriangleClipping.SutherlandHodgman.ClipPolygon(clippingVectorList, clippingPolygon);
int vertexcount = clippedTriangle.Count;
if (vertexcount < 3)
{
continue;
}
clippedVerticesRD.Add(RestoreRDVertex(clippedTriangle[0], temporaryOrigin));
clippedVerticesRD.Add(RestoreRDVertex(clippedTriangle[1], temporaryOrigin));
clippedVerticesRD.Add(RestoreRDVertex(clippedTriangle[2], temporaryOrigin));
// add extra vectors. vector makes a triangle with the first and the previous vector.
for (int j = 3; j < vertexcount; j++)
{
clippedVerticesRD.Add(RestoreRDVertex(clippedTriangle[0], temporaryOrigin));
clippedVerticesRD.Add(RestoreRDVertex(clippedTriangle[j - 1], temporaryOrigin));
clippedVerticesRD.Add(RestoreRDVertex(clippedTriangle[j], temporaryOrigin));
}
}
}
}
private List <Vector3> CreateClippingPolygon(RDBoundingBox boundingBox)
{
List <Vector3> output = new List <Vector3>(4);
output.Add(new Vector3(0, 0, 0));
output.Add(new Vector3((float)boundingBox.width, 0, 0));
output.Add(new Vector3((float)boundingBox.width, 0, (float)boundingBox.height));
output.Add(new Vector3(0, 0, (float)boundingBox.height));
return(output);
}
private bool PointISInsideArea(Vector3 vector, RDBoundingBox boundingBox)
{
if (vector.x < 0 || vector.x > boundingBox.width)
{
return(false);
}
if (vector.z < 0 || vector.z > boundingBox.height)
{
return(false);
}
return(true);
}
private trianglePosition GetTrianglePosition(Vector3 point1, Vector3 point2, Vector3 point3, RDBoundingBox boundingBox)
{
int counter = 0;
if (PointISInsideArea(point1, boundingBox))
{
counter++;
}
if (PointISInsideArea(point2, boundingBox))
{
counter++;
}
if (PointISInsideArea(point3, boundingBox))
{
counter++;
}
if (counter == 0)
{
return(trianglePosition.outside);
}
else if (counter == 3)
{
return(trianglePosition.inside);
}
else
{
return(trianglePosition.overlap);
}
}