public void DrawTriangleBottom(Vectex v1, Vectex v2, Vectex v3)
{
//先确定好形状
if (v1.pos.x > v2.pos.x)
{
Vectex p;
p = Vectex.Colone(v1);
v1 = Vectex.Colone(v2);
v2 = Vectex.Colone(p);
}
float y, dy, dy2, t;
int yIndex, stepy;
stepy = -1;
dy = v1.pos.y - v3.pos.y;
y = v1.pos.y;
yIndex = (int)y;
for (; yIndex > v3.pos.y; yIndex += stepy)
{
//求该y值处的左右顶点
dy2 = yIndex - v3.pos.y;
t = dy2 / dy;
Vectex left, right;
left = NewMath.Interp(v3, v1, t);
right = NewMath.Interp(v3, v2, t);
DrawScanline(left, right, yIndex);
}
}
//光栅化开始
public void Rasterization(Vectex v1, Vectex v2, Vectex v3)
{
//保护?
if (v1.pos.y == v2.pos.y && v1.pos.y == v3.pos.y)
{
return;
}
//交换v1,v2,v3使纵向1<2<3
if (v1.pos.y > v2.pos.y)
{
Vectex v = Vectex.Colone(v2);
v2 = Vectex.Colone(v1);
v1 = Vectex.Colone(v);
}
if (v1.pos.y > v3.pos.y)
{
Vectex v = Vectex.Colone(v3);
v3 = Vectex.Colone(v1);
v1 = Vectex.Colone(v);
}
if (v2.pos.y > v3.pos.y)
{
Vectex v = Vectex.Colone(v3);
v3 = Vectex.Colone(v2);
v2 = Vectex.Colone(v);
}
//初步分析
if (v1.pos.y == v2.pos.y)
{
DrawTriangleTop(v1, v2, v3);
}
else if (v2.pos.y == v3.pos.y)
{
DrawTriangleBottom(v2, v3, v1);
}
else//分割三角形
{
//重点在于找到13边上的中间点 作为新顶点
Vectex newMiddle = new Vectex();
float x1 = v1.pos.x;
float y1 = v1.pos.y;
float dx = v3.pos.x - v1.pos.x;
float dy = v3.pos.y - v1.pos.y;
//确定纵坐标
float y = v2.pos.y;
//进行插值
float dy2 = y - v1.pos.y;
float t = dy2 / dy;
newMiddle = NewMath.Interp(v1, v3, t);
//来吧
DrawTriangleBottom(newMiddle, v2, v1);
DrawTriangleTop(newMiddle, v2, v3);
}
}
//光照相关
public void SetLightingColor(Vectex v1)
{
//将顶点转换到世界空间中
Vectex v = Vectex.Colone(v1);
//求世界空间中的法向量
Vector3 n = v.nomal * device.ts.world.Inverse().Transpose();
//光线向量
Vector3 l = device.light.lightPosition - v.pos;
//公式 c=cr(ca+cl*n*l)
float t = NewMath.Round(Vector3.Dot(n, l), 0, 1);
Color c = device.light.diffuse * (device.light.ambient + device.light.sourse * t);
c = NewMath.Round(c, 0, 1);
v1.lightcolor = c;
}
public void DrawTriangle(Vectex v1, Vectex v2, Vectex v3)
{
Vector3 p1, p2, p3, c1, c2, c3;
//背面剔除 2 3
p1 = v1.pos * (device.ts.world * device.ts.view);
p2 = v2.pos * (device.ts.world * device.ts.view);
p3 = v3.pos * (device.ts.world * device.ts.view);
if (device.renderState != RenderState.WIRE)
{
if (!CheckIsFront(p1, p2, p3))
{
return;
}
}
//设置顶点光照颜色 4
if (device.lightMode == LightMode.ON)
{
SetLightingColor(v1);
SetLightingColor(v2);
SetLightingColor(v3);
}
//坐标转换 123
p1 = v1.pos * device.ts.transform;
p2 = v2.pos * device.ts.transform;
p3 = v3.pos * device.ts.transform;
//cvv裁剪 123
if (!p1.CheckCVV() || !p2.CheckCVV() || !p3.CheckCVV())
{
return;
}
//归一化得到屏幕坐标 123
c1 = Vector3.Homogenize(device.ts, p1);
c2 = Vector3.Homogenize(device.ts, p2);
c3 = Vector3.Homogenize(device.ts, p3);
//坐标转换完毕 c为屏幕坐标,顶点其他信息来自v
//开始渲染
//初始化渲染顶点信息 123
Vectex d1, d2, d3;
//顶点的color等信息来自v
d1 = Vectex.Colone(v1);
d2 = Vectex.Colone(v2);
d3 = Vectex.Colone(v3);
//顶点位置信息来自最终屏幕坐标c
d1.pos = Vector3.Colone(c1);
d2.pos = Vector3.Colone(c2);
d3.pos = Vector3.Colone(c3);
//顶点w信息来自未归一化的p，w代表原z值
d1.pos.w = p1.w;
d2.pos.w = p2.w;
d3.pos.w = p3.w;
//初始化顶点的rhw数据并用此数据加工颜色，uv数据,为后续顶点颜色的深度插值作准备
d1.InitRhw();
d2.InitRhw();
d3.InitRhw();
//线框模式 1
if (device.renderState == RenderState.WIRE)
{
DrawLine(d1, d2);
DrawLine(d1, d3);
DrawLine(d3, d2);
}
else
{
//color2
Rasterization(d1, d2, d3);
}
}
