public static CSGVertex Interpolate(CSGVertex _vertexA, CSGVertex _vertexB, float _step)
{
CSGVertex result = new CSGVertex();
result.m_position = Vector3.Lerp(_vertexA.m_position, _vertexB.m_position, _step);
result.m_normal = Vector3.Lerp(_vertexA.m_normal, _vertexB.m_normal, _step);
result.m_uv = Vector2.Lerp(_vertexA.m_uv, _vertexB.m_uv, _step);
result.m_color = (_vertexA.m_color + _vertexB.m_color) / 2f;
return(result);
}
// Split `polygon` by this plane if needed, then put the polygon or polygon
// fragments in the appropriate lists. Coplanar polygons go into either
// `coplanarFront` or `coplanarBack` depending on their orientation with
// respect to this plane. Polygons in front or in back of this plane go into
// either `front` or `back`.
public void SplitPolygon(CSGPolygon _polygon, List <CSGPolygon> _coplanarFront,
List <CSGPolygon> _coplanarBack, List <CSGPolygon> _front, List <CSGPolygon> _back)
{
// Classify each point as well as the entire polygon into one of the above
// four classes.
PolygonType polygonType = 0;
List <PolygonType> types = new List <PolygonType>();
for (int i = 0; i < _polygon.m_vertices.Count; i++)
{
float t = Vector3.Dot(m_normal, _polygon.m_vertices[i].m_position) - m_planeWidth;
PolygonType type = (t < -CSG.EPSILON) ? PolygonType.Back : ((t > CSG.EPSILON) ?
PolygonType.Front : PolygonType.Coplanar);
polygonType |= type;
types.Add(type);
}
// Put the polygon in the correct list, splitting it when necessary.
switch (polygonType)
{
case PolygonType.Coplanar:
{
if (Vector3.Dot(m_normal, _polygon.m_plane.m_normal) > 0)
{
_coplanarFront.Add(_polygon);
}
else
{
_coplanarBack.Add(_polygon);
}
}
break;
case PolygonType.Front:
{
_front.Add(_polygon);
}
break;
case PolygonType.Back:
{
_back.Add(_polygon);
}
break;
case PolygonType.Spanning:
{
List <CSGVertex> front = new List <CSGVertex>();
List <CSGVertex> back = new List <CSGVertex>();
for (int vertexIter = 0; vertexIter < _polygon.m_vertices.Count; vertexIter++)
{
int nextVertexIndex = (vertexIter + 1) % _polygon.m_vertices.Count;
PolygonType currentType = types[vertexIter];
PolygonType nextType = types[nextVertexIndex];
CSGVertex currentVertex = _polygon.m_vertices[vertexIter];
CSGVertex nextVertex = _polygon.m_vertices[nextVertexIndex];
if (currentType != PolygonType.Back)
{
front.Add(currentVertex);
}
if (currentType != PolygonType.Front)
{
back.Add(currentVertex);
}
if ((currentType | nextType) == PolygonType.Spanning)
{
float step = (m_planeWidth - Vector3.Dot(m_normal, currentVertex.m_position)) / Vector3.Dot(m_normal, nextVertex.m_position - currentVertex.m_position);
CSGVertex vertex = CSGVertex.Interpolate(currentVertex, nextVertex, step);
front.Add(vertex);
back.Add(vertex);
}
}
if (front.Count >= 3)
{
_front.Add(new CSGPolygon(front));
}
if (back.Count >= 3)
{
_back.Add(new CSGPolygon(back));
}
}
break;
}
}
