//从小到大输入
private void RasterBottomTriangle(VertexOut v1, VertexOut v2, VertexOut v3, BaseShader shader)
{
VertexOut left = v1;
VertexOut right = v2;
VertexOut dest = v3;
float weight = 0;
VertexOut newLeft;
VertexOut newRight;
if (left.posProjective.x > right.posProjective.x)
{
VertexOut tmp = left;
left = right;
right = tmp;
}
int dy = (int)dest.posProjective.y - (int)left.posProjective.y + 1;
for (int i = 0; i < dy; i++)
{
if (dy != 0)
{
weight = (float)i / dy;
}
newLeft = LerpVertexOut(left, dest, weight);
newRight = LerpVertexOut(right, dest, weight);
newLeft.posProjective.y = left.posProjective.y + i;
newRight.posProjective.y = left.posProjective.y + i;
ScanLinePerRow(newLeft, newRight, shader);
}
}
//按列逐行扫描
private void ScanLinePerRow(VertexOut left, VertexOut right, BaseShader shader)
{
VertexOut current;
int length = (int)right.posProjective.x - (int)left.posProjective.x;
if (length == 0)
{
return;
}
for (int i = 0; i <= length; i++)
{
float weight = (float)i / length;
current = LerpVertexOut(left, right, weight);
if (shader.ZTest == true)
{
if (current.posProjective.z >= 0.5f &&
current.posProjective.z > backBuffer.GetDepth((int)current.posProjective.x, (int)current.posProjective.y))
{
continue;
}
}
if (shader.ZWrite == true)
{
backBuffer.DrawDepth((int)current.posProjective.x, (int)current.posProjective.y, current.posProjective.z);
}
current.posProjective.x = left.posProjective.x + i;
current.posProjective.y = left.posProjective.y;
//透视纹理处理
shader.ProjectedMapRestore(current);
//片段着色
backBuffer.DrawPixel((int)current.posProjective.x, (int)current.posProjective.y, shader.FragmentShader(current));
}
}
public void Render()
{
////测试画线函数------>>>>>>
//VertexOut pA = new VertexOut();
//pA.posProjective = new Vector4D(100,0,0,1);
//VertexOut pB = new VertexOut();
//pB.posProjective = new Vector4D(100, 100, 0, 1);
//BresenhamLineRasterization(pA, pB);
//return;
////测试画线函数<<<<<<<--------
///
Vector3D tmp = scene.camera.transform.GetPosition();
cameraPosition = new Vector3D(tmp.x, tmp.y, tmp.z);
//cameraPosition.x = -cameraPosition.x;
//cameraPosition.y = -cameraPosition.y;
//cameraPosition.z = -cameraPosition.z;
Vector3D up = new Vector3D(0, 1, 0);
//up.x = -up.x;
//up.y = -up.y;
//up.z = -up.z;
viewMatrix.SetLookAt(cameraPosition, new Vector3D(0, 0, 0), up);
backBuffer.Clear();
//scene.camera
for (int i = 0; i < scene.gameObjects.Count; i++)
{
GameObject3D gameObject = scene.gameObjects[i];
BaseShader shader = gameObject.meshRenderer.material.shader;
shader.SetModelMatrix(gameObject.transform.ToMatrix());
shader.SetViewMatrix(viewMatrix);
shader.SetEyePos(cameraPosition);
shader.SetProjectMatrix(projectMatrix);
shader.SetLight(scene.light);
//图元装配
Mesh mesh = gameObject.meshRenderer.mesh;
//Debug.LogError("%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%");
for (int j = 0; j < mesh.indices.Length; j += 3)
{
Vertex p1, p2, p3;
p1 = mesh.vertices[mesh.indices[j]];
p2 = mesh.vertices[mesh.indices[j + 1]];
p3 = mesh.vertices[mesh.indices[j + 2]];
//顶点着色(遍历三角形)
VertexOut vertexOut1, vertexOut2, vertexOut3;
vertexOut1 = shader.VertexShader(p1);
vertexOut2 = shader.VertexShader(p2);
vertexOut3 = shader.VertexShader(p3);
shader.ProjectedMap(vertexOut1);
shader.ProjectedMap(vertexOut2);
shader.ProjectedMap(vertexOut3);
//背面裁剪
if (shader.backFaceCulling)
{
if (polygonMode != PolygonMode.Wire && !BackFaceCulling(vertexOut1.posWorld, vertexOut2.posWorld, vertexOut3.posWorld))
{
continue;
}
}
//透视处理
PerspectiveDivision(vertexOut1);
PerspectiveDivision(vertexOut2);
PerspectiveDivision(vertexOut3);
//几何裁剪
//屏幕空间转换
vertexOut1.posProjective = Matrix4x4.MultiplyVector4D(viewPortMatrix, vertexOut1.posProjective);
vertexOut2.posProjective = Matrix4x4.MultiplyVector4D(viewPortMatrix, vertexOut2.posProjective);
vertexOut3.posProjective = Matrix4x4.MultiplyVector4D(viewPortMatrix, vertexOut3.posProjective);
//Debug.LogError("vertexOut1.posProjective " + vertexOut1.posProjective.x
// + " " + vertexOut1.posProjective.y + " " + vertexOut1.posProjective.z );
//Debug.LogError("vertexOut2.posProjective " + vertexOut2.posProjective.x
// + " " + vertexOut2.posProjective.y + " " + vertexOut2.posProjective.z );
//Debug.LogError("vertexOut3.posProjective " + vertexOut3.posProjective.x
// + " " + vertexOut3.posProjective.y + " " + vertexOut3.posProjective.z );
//Debug.LogError("-----------------");
//片段着色
if (polygonMode == PolygonMode.Wire)
{
//线框模式
BresenhamLineRasterization(vertexOut1, vertexOut2);
BresenhamLineRasterization(vertexOut1, vertexOut3);
BresenhamLineRasterization(vertexOut2, vertexOut3);
}
else
{
//三角形填充模式
EdgeWalkingFillRasterization(vertexOut1, vertexOut2, vertexOut3, shader);
}
}
}
}
private void EdgeWalkingFillRasterization(VertexOut v1, VertexOut v2, VertexOut v3, BaseShader shader)
{
//先把三个点按y从小到大排序
VertexOut[] targets = { v1, v2, v3 };
VertexOut tmp;
if (targets[0].posProjective.y > targets[1].posProjective.y)
{
tmp = targets[0];
targets[0] = targets[1];
targets[1] = tmp;
}
if (targets[0].posProjective.y > targets[2].posProjective.y)
{
tmp = targets[0];
targets[0] = targets[2];
targets[2] = tmp;
}
if (targets[1].posProjective.y > targets[2].posProjective.y)
{
tmp = targets[1];
targets[1] = targets[2];
targets[2] = tmp;
}
if ((int)targets[0].posProjective.y == (int)targets[1].posProjective.y)
{
//下三角形
RasterBottomTriangle(targets[0], targets[1], targets[2], shader);
}
else if ((int)targets[1].posProjective.y == (int)targets[2].posProjective.y)
{
//上三角形
RasterTopTriangle(targets[0], targets[1], targets[2], shader);
}
else
{
//需要分割为上三角形下三角形
float weight = (targets[1].posProjective.y - targets[0].posProjective.y)
/ (targets[2].posProjective.y - targets[0].posProjective.y);
VertexOut vertexOutNew = LerpVertexOut(targets[0], targets[2], weight);
vertexOutNew.posProjective.y = targets[1].posProjective.y;
RasterTopTriangle(targets[0], vertexOutNew, targets[1], shader);
RasterBottomTriangle(vertexOutNew, targets[1], targets[2], shader);
}
}
