public override void Render()
{
if (mesh == null)
{
return;
}
Vertex[] tempVerts = new Vertex[] { new Vertex(), new Vertex(), new Vertex() };
int length = mesh.Surfaces.Length;
for (int i = 0; i < length; i++)
{
var surface = mesh.Surfaces[i];
//不把变换后的结果保存顶点中，否则下次渲染顶点位置就不对了
tempVerts[0].Copy(mesh.Vertices[surface.A]);
tempVerts[1].Copy(mesh.Vertices[surface.B]);
tempVerts[2].Copy(mesh.Vertices[surface.C]);
Vector v1 = tempVerts[0].pos;
Vector v2 = tempVerts[1].pos;
Vector v3 = tempVerts[2].pos;
//Obj -> World
Vector wp1 = transform.ApplyObj2World(v1);
Vector wp2 = transform.ApplyObj2World(v2);
Vector wp3 = transform.ApplyObj2World(v3);
//World -> view
Vector vp1 = transform.ApplyWorldToView(wp1);
Vector vp2 = transform.ApplyWorldToView(wp2);
Vector vp3 = transform.ApplyWorldToView(wp3);
//背面消隐
if (TransformUtility.IsBackCulling(vp1, vp2, vp3))
{
continue;
}
//view -> 齐次裁剪空间
Vector cp1 = transform.ApplyViewToClip(vp1);
Vector cp2 = transform.ApplyViewToClip(vp2);
Vector cp3 = transform.ApplyViewToClip(vp3);
// CVV裁剪
//if(...)
//变换到齐次裁剪空间后，w值保存view空间下的z信息
//保存 1/z 用于后面求u'、v'
tempVerts[0].onePerZ = 1 / cp1.w;
tempVerts[1].onePerZ = 1 / cp2.w;
tempVerts[2].onePerZ = 1 / cp3.w;
tempVerts[0].u *= tempVerts[0].onePerZ;
tempVerts[0].v *= tempVerts[0].onePerZ;
tempVerts[1].u *= tempVerts[1].onePerZ;
tempVerts[1].v *= tempVerts[1].onePerZ;
tempVerts[2].u *= tempVerts[2].onePerZ;
tempVerts[2].v *= tempVerts[2].onePerZ;
//透视除法 齐次裁剪空间 -> NDC空间
cp1 /= cp1.w;
cp2 /= cp2.w;
cp3 /= cp3.w;
//屏幕映射 NDC空间下 -> 屏幕空间
Vector sp1 = Screen.ComputeToScreenPos(cp1);
Vector sp2 = Screen.ComputeToScreenPos(cp2);
Vector sp3 = Screen.ComputeToScreenPos(cp3);
tempVerts[0].pos = sp1;
tempVerts[1].pos = sp2;
tempVerts[2].pos = sp3;
switch (Application.RenderType)
{
case RenderType.Wireframe:
graphics.DrawTriangleLine(tempVerts[0].pos, tempVerts[1].pos, tempVerts[2].pos, Color.Red);
break;
case RenderType.Fill:
graphics.FillTriangle(tempVerts[0].pos, tempVerts[1].pos, tempVerts[2].pos, Color.Red);
break;
case RenderType.VertexColor:
graphics.FillTriangle(tempVerts[0], tempVerts[1], tempVerts[2]);
break;
case RenderType.Texture:
graphics.FillTriangle(tempVerts[0], tempVerts[1], tempVerts[2]);
break;
}
}
}
