//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);
}
}
public void ProjectedMapRestore(VertexOut vertexOut)
{
float w = 1.0f / vertexOut.oneDivZ;
vertexOut.posWorld.MultiplyNum(w);
vertexOut.texcoord.MultiplyNum(w);
vertexOut.color.MultiplyNum(w);
}
//处理透视纹理映射
public void ProjectedMap(VertexOut vertexOut)
{
//处理透视纹理映射
vertexOut.oneDivZ = 1.0f / vertexOut.posProjective.w;
vertexOut.posWorld.MultiplyNum(vertexOut.oneDivZ);
vertexOut.texcoord.MultiplyNum(vertexOut.oneDivZ);
vertexOut.color.MultiplyNum(vertexOut.oneDivZ);
}
private void PerspectiveDivision(VertexOut vertexOut)
{
vertexOut.posProjective.x /= vertexOut.posProjective.w;
vertexOut.posProjective.y /= vertexOut.posProjective.w;
vertexOut.posProjective.z /= vertexOut.posProjective.w;
vertexOut.posProjective.w = 1;
//[-1,1] to [0,1]
vertexOut.posProjective.z = (vertexOut.posProjective.z + 1.0f) * 0.5f;
}
//Bresenham画线法 用整数加减法代替浮点数加减法
private void BresenhamLineRasterization(VertexOut from, VertexOut to)
{
int x = (int)from.posProjective.x;
int y = (int)from.posProjective.y;
int toX = (int)to.posProjective.x;
int toY = (int)to.posProjective.y;
int deltax = toX - x;
int deltay = toY - y;
int stepx = 1;
int stepy = 1;
if (deltax < 0)
{
stepx = -1;
}
if (deltay < 0)
{
stepy = -1;
}
int eps = 0;//误差累计
deltax = Mathf.Abs(deltax);
deltay = Mathf.Abs(deltay);
if (deltax > deltay)
{
for (; x != toX; x += stepx)
{
eps += deltay;
if ((eps << 1) >= deltax)
{
y += stepy;
eps -= deltax;
}
backBuffer.DrawPixel(x, y, Color.White());
}
}
else
{
for (; y != toY; y += stepy)
{
eps += deltax;
if ((eps << 1) >= deltay)
{
x += stepx;
eps -= deltay;
}
backBuffer.DrawPixel(x, y, Color.White());
}
}
}
private VertexOut LerpVertexOut(VertexOut v1, VertexOut v2, float weight)
{
VertexOut vertexOut = new VertexOut();
vertexOut.posProjective = Vector4D.Lerp(v1.posProjective, v2.posProjective, weight);
vertexOut.posWorld = Vector4D.Lerp(v1.posWorld, v2.posWorld, weight);
vertexOut.color = Color.Lefp(v1.color, v2.color, weight);
vertexOut.normal = Vector3D.Lerp(v1.normal, v2.normal, weight);
vertexOut.texcoord = Vector2D.Lerp(v1.texcoord, v2.texcoord, weight);
vertexOut.oneDivZ = (1 - weight) * v1.oneDivZ + weight * v2.oneDivZ;
return(vertexOut);
}
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);
}
}
public override VertexOut VertexShader(Vertex vertexIn)
{
VertexOut vertexOut = new VertexOut();
vertexOut.posWorld = Matrix4x4.MultiplyVector4D(modelMatrix, vertexIn.position);
vertexOut.posProjective = Matrix4x4.MultiplyVector4D(viewMatrix, vertexOut.posWorld);
vertexOut.posProjective = Matrix4x4.MultiplyVector4D(projectedMatrix, vertexOut.posProjective);
vertexOut.color = vertexIn.color.Copy();
vertexOut.normal = vertexIn.normal.Copy();
vertexOut.normal = Matrix4x4.MultiplyVector4D(modelMatrixInverse, vertexOut.normal.ToVector4D()).ToVector3D();
vertexOut.texcoord = vertexIn.texcoord.Copy();
//vertexOut.oneDivZ = 1.0f / vertexOut.posProjective.w;
//vertexOut.posWorld.MultiplyNum(vertexOut.oneDivZ);
//vertexOut.texcoord.MultiplyNum(vertexOut.oneDivZ);
//vertexOut.color.MultiplyNum(vertexOut.oneDivZ);
return(vertexOut);
}
public override Color FragmentShader(VertexOut vertexIn)
{
Color color = texture.Sample(vertexIn.texcoord.x, vertexIn.texcoord.y);
//Color color = Color.Red();
if (light != null)
{
if (light.GetType() == typeof(DirectionalLight))
{
color = color * ((DirectionalLight)light).Lighting(
ambientColor,
diffuseColor,
specularColor,
vertexIn.posWorld.ToVector3D(),
vertexIn.normal,
Vector3D.Minus(eyePos, vertexIn.posWorld));
color.a = 1;
}
}
//return vertexIn.color;
return(color);
}
//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 virtual Color FragmentShader(VertexOut vertexIn)
{
return(null);
}