public OOModel(MannulDraw drawer)
{
Drawer = drawer;
MeshFilter mf = drawer.gameObject.GetComponent <MeshFilter>();
Model = new OOMesh(mf);
Box = new OOBox(Vector3.one * float.MaxValue, Vector3.one * float.MinValue);
UpdateTransform();
Head = new OOItem();
Tail = new OOItem();
Tail.CNext = null;
Head.CPrev = null;
Head.CNext = Tail;
Tail.CPrev = Head;
CanOcclude = 1;
// GeoDebugDrawUtils.DrawAABB(Box.Min, Box.Max);
}
/// <summary>
/// 绘制一个物体到缓冲区
/// </summary>
/// <param name="obj">待绘制物体</param>
private void DrawOccluder(OOModel obj)
{
// 获取物体的模型
OOMesh mdl = obj.Model;
// 计算 ModelView 矩阵.注意：这里需要相机的变换矩阵的逆矩阵
// 另一问题：左手系和右手系问题。
Matrix4x4 modelViewMatrix = mView * obj.ModelWorldMatrix;
// 变换mesh的顶点到 相机空间 和 裁剪空间
for (int i = 0; i < mdl.NumVert; i++)
{
// Vector3 p = obj.ModelWorldMatrix.MultiplyPoint3x4(mdl.Vertices[i]);
Vector4 tmp = modelViewMatrix.MultiplyPoint3x4(mdl.Vertices[i]);
mdl.CameraSpaceVertices[i] = tmp;
tmp.w = 1;
mdl.ClipSpaceVertices[i] = mProject * tmp;
}
int xmin = 100000;
int xmax = 0;
int ymin = 100000;
int ymax = 0;
// 遍历所有面
for (int i = 0; i < mdl.NumFace; i++)
{
// 面索引
int p1 = mdl.Faces[i][0];
int p2 = mdl.Faces[i][1];
int p3 = mdl.Faces[i][2];
// 计算法向量。此处可以优化成：初始化时计算，而后变换一下法向量即可。
// 构建右手坐标系 逆时针为正方向
Vector3 a = mdl.CameraSpaceVertices[p2] - mdl.CameraSpaceVertices[p1];
Vector3 b = mdl.CameraSpaceVertices[p3] - mdl.CameraSpaceVertices[p1];
Vector3 n = Vector3.Cross(a, b);
// 背面剔除。可计算相机的朝向，然后与三角面的法线计算即可。
// 此处实际上计算 Camera 空间 原点到平面的距离是否小于0
if (Vector3.Dot(n, mdl.CameraSpaceVertices[p1]) < 0)
{
mClip.mClipSpaceVertices[0] = mdl.ClipSpaceVertices[p1];
mClip.mClipSpaceVertices[1] = mdl.ClipSpaceVertices[p2];
mClip.mClipSpaceVertices[2] = mdl.ClipSpaceVertices[p3];
// 裁剪计算
int nv = mClip.ClipAndProject(3);
#if TEST_DRAW_ONE
DebugUtils.Info("ClipAndProject", string.Format("world1({0}, {1})", mClip.mScreenSpaceVertices[0][0], mClip.mScreenSpaceVertices[0][1]));
DebugUtils.Info("ClipAndProject", string.Format("world2({0}, {1})", mClip.mScreenSpaceVertices[1][0], mClip.mScreenSpaceVertices[1][1]));
DebugUtils.Info("ClipAndProject", string.Format("world3({0}, {1})", mClip.mScreenSpaceVertices[2][0], mClip.mScreenSpaceVertices[2][1]));
#endif
// 裁剪判断
if (nv > 2)
{
// 裁剪后，计算屏幕区域的AABB
for (int j = 0; j < nv; j++)
{
if (mClip.mScreenSpaceVertices[j][0] < xmin)
{
xmin = mClip.mScreenSpaceVertices[j][0];
}
else
{
if (mClip.mScreenSpaceVertices[j][0] > xmax)
{
xmax = mClip.mScreenSpaceVertices[j][0];
}
}
if (mClip.mScreenSpaceVertices[j][1] < ymin)
{
ymin = mClip.mScreenSpaceVertices[j][1];
}
else if (mClip.mScreenSpaceVertices[j][1] > ymax)
{
ymax = mClip.mScreenSpaceVertices[j][1];
}
}
// 绘制多边形到缓冲
Map.DrawPolygon(mClip.mScreenSpaceVertices, nv);
}
}
}
// 设置该区域内有被覆盖
Map.SetDirtyRectangle(xmin, ymin, xmax, ymax);
}