public IVertexOutputData Process(IVertexInputData input)
{
IVertexOutputData output = new VertexOutputData();
output.clip = MVP * input.vertex;
output.viewNormal = N * input.normal;
return(output);
}
private IVertexOutputData[] ClipPolygon(IVertexOutputData[] polygon)
{
for (int planeIndex = 0; planeIndex < 6; planeIndex++)
{
List <IVertexOutputData> vdatas = new List <IVertexOutputData>();
int vi = planeIndex / 2;
int sign = planeIndex % 2 == 0 ? 1 : -1;
for (int pointIndex = 0; pointIndex < polygon.Length; pointIndex++)
{
int index0 = pointIndex;
int index1 = pointIndex == polygon.Length - 1 ? 0 : pointIndex + 1;
IVertexOutputData v0 = polygon[index0];
IVertexOutputData v1 = polygon[index1];
Vector4 p0 = v0.clip;
Vector4 p1 = v1.clip;
Vector3 n0 = v0.viewNormal;
Vector3 n1 = v1.viewNormal;
float d0 = (p0[vi] + p0.w * sign) * p0.w;
float d1 = (p1[vi] + p1.w * sign) * p1.w;
float ds = d0 * d1;
if (ds < 0)
{
// 边与裁剪面相交
float u = d0 / (d0 - d1);
Vector4 p = p0 + (p1 - p0) * u;
Vector3 n = n0 + (n1 - n0) * u;
if (sign * d0 > 0)
{
vdatas.Add(v0);
}
IVertexOutputData data = new VertexOutputData();
data.clip = p;
data.viewNormal = n;
vdatas.Add(data);
}
else if (MathS.Abs(d0) < Threshold)
{
// p0点在裁剪面上
vdatas.Add(v0);
}
else if (sign * d0 > 0 && sign * d1 >= 0)
{
// 边完全位于裁剪面之内
vdatas.Add(v0);
}
}
polygon = vdatas.ToArray();
}
return(polygon);
}
public IVertexOutputData Triangle(IVertexOutputData[] clips, Vector2[] screens, int[] pixel)
{
Vector2 center = new Vector2(pixel[0], pixel[1]);
float a = MathS.Abs(Vector2.Cross(screens[1] - screens[0], screens[2] - screens[0]) * 0.5f);
// 重心法求插值系数
float a0 = MathS.Abs(Vector2.Cross(screens[1] - screens[0], center - screens[0]) * 0.5f) / a;
float a1 = MathS.Abs(Vector2.Cross(screens[2] - screens[1], center - screens[1]) * 0.5f) / a;
float a2 = MathS.Abs(Vector2.Cross(screens[0] - screens[2], center - screens[2]) * 0.5f) / a;
// 插值
IVertexOutputData lerp = new VertexOutputData();
lerp.clip = a0 * clips[0].clip + a1 * clips[1].clip + a2 * clips[2].clip;
lerp.viewNormal = a0 * clips[0].viewNormal + a1 * clips[1].viewNormal + a2 * clips[2].viewNormal;
return(lerp);
}
public ITriangle[] Process(IDrawCall drawCall, ICamera camera)
{
// vertex shade
vertexShade.MVP = camera.P * camera.V * drawCall.M;
vertexShade.N = (camera.V * drawCall.M).Inverse().Transpose().Minor(3, 3);
Vector4[] vertices = drawCall.vertices;
Vector3[] normals = drawCall.normals;
IVertexOutputData[] outputs = new VertexOutputData[vertices.Length];
for (int vIndex = 0; vIndex < vertices.Length; vIndex++)
{
IVertexInputData input = new VertexInputData();
input.vertex = vertices[vIndex];
input.normal = normals[vIndex];
outputs[vIndex] = vertexShade.Process(input);
}
// primitive assembly
ITriangle[] primitives = primitiveAssemble.Process(outputs, drawCall.indices);
Queue <ITriangle> triangles = new Queue <ITriangle>();
for (int pIndex = 0; pIndex < primitives.Length; pIndex++)
{
// back-face culling
ITriangle t = cull.Process(primitives[pIndex]);
if (t != null)
{
// clipping
ITriangle[] ts = clip.Process(t);
if (ts != null)
{
foreach (ITriangle each in ts)
{
triangles.Enqueue(each);
}
}
}
}
return(triangles.ToArray());
}
