protected void AddPolygon(ref SmallList <Vertex> vertices)
{
if (vertices.Count <= 2)
{
return;
}
int vertexCount = VertexCount;
Vertex vertex;
vertices.Get(0, out vertex);
AddVertex(ref vertex);
vertices.Get(1, out vertex);
AddVertex(ref vertex);
for (int i = 3; i < vertices.Count; i += 2)
{
vertices.Get(i - 1, out vertex);
AddVertex(ref vertex);
vertices.Get(i, out vertex);
AddVertex(ref vertex);
AddIndices(vertexCount, vertexCount + i - 2, vertexCount + i - 1, vertexCount + i);
}
if (vertices.Count % 2 == 1)
{
vertices.Get(vertices.Count - 1, out vertex);
AddVertex(ref vertex);
AddIndices(vertexCount, vertexCount + vertices.Count - 2, vertexCount + vertices.Count - 1);
}
}
/// <summary>
/// Sutherland-Hodgman algorithmでクリップする。
/// </summary>
/// <param name="list">三角形か凸な四角形</param>
void SutherlandHodgman(ref SmallList <Vertex> list)
{
var list2 = new SmallList <Vertex>();
Vertex vertex, prev, temporary;
list.Get(list.Count - 1, out prev);
for (int i = 0; i < list.Count; ++i)
{
list.Get(i, out vertex);
if (vertex.Position.x >= mask.x)
{
if (prev.Position.x < mask.x)
{
var t = (mask.x - vertex.Position.x) / (prev.Position.x - vertex.Position.x);
Vertex.Lerp(ref vertex, ref prev, t, out temporary);
list2.Add(ref temporary);
}
list2.Add(ref vertex);
}
else if (prev.Position.x >= mask.x)
{
var t = (mask.x - vertex.Position.x) / (prev.Position.x - vertex.Position.x);
Vertex.Lerp(ref vertex, ref prev, t, out temporary);
list2.Add(ref temporary);
}
prev = vertex;
}
list.Clear();
if (list2.Count <= 2)
{
return;
}
list2.Get(list2.Count - 1, out prev);
for (int i = 0; i < list2.Count; ++i)
{
list2.Get(i, out vertex);
if (vertex.Position.y >= mask.y)
{
if (prev.Position.y < mask.y)
{
var t = (mask.y - vertex.Position.y) / (prev.Position.y - vertex.Position.y);
Vertex.Lerp(ref vertex, ref prev, t, out temporary);
list.Add(ref temporary);
}
list.Add(ref vertex);
}
else if (prev.Position.y >= mask.y)
{
var t = (mask.y - vertex.Position.y) / (prev.Position.y - vertex.Position.y);
Vertex.Lerp(ref vertex, ref prev, t, out temporary);
list.Add(ref temporary);
}
prev = vertex;
}
if (list.Count <= 2)
{
return;
}
list2.Clear();
list.Get(list.Count - 1, out prev);
for (int i = 0; i < list.Count; ++i)
{
list.Get(i, out vertex);
if (vertex.Position.x <= mask.z)
{
if (prev.Position.x > mask.z)
{
var t = (mask.z - vertex.Position.x) / (prev.Position.x - vertex.Position.x);
Vertex.Lerp(ref vertex, ref prev, t, out temporary);
list2.Add(ref temporary);
}
list2.Add(ref vertex);
}
else if (prev.Position.x <= mask.z)
{
var t = (mask.z - vertex.Position.x) / (prev.Position.x - vertex.Position.x);
Vertex.Lerp(ref vertex, ref prev, t, out temporary);
list2.Add(ref temporary);
}
prev = vertex;
}
list.Clear();
if (list2.Count <= 2)
{
return;
}
list2.Get(list2.Count - 1, out prev);
for (int i = 0; i < list2.Count; ++i)
{
list2.Get(i, out vertex);
if (vertex.Position.y <= mask.w)
{
if (prev.Position.y > mask.w)
{
var t = (mask.w - vertex.Position.y) / (prev.Position.y - vertex.Position.y);
Vertex.Lerp(ref vertex, ref prev, t, out temporary);
list.Add(ref temporary);
}
list.Add(ref vertex);
}
else if (prev.Position.y <= mask.w)
{
var t = (mask.w - vertex.Position.y) / (prev.Position.y - vertex.Position.y);
Vertex.Lerp(ref vertex, ref prev, t, out temporary);
list.Add(ref temporary);
}
prev = vertex;
}
}