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);
}
}
//扫描填色
public void DrawScanline(Vectex v1, Vectex v2, int yIndex)
{
float x1 = v1.pos.x;
float x2 = v2.pos.x;
float dx = v2.pos.x - v1.pos.x;
float x = x1;
//扫描密度，可以减小
float stepx = 0.5f;
int xIndex = (int)(x + 0.5f);
for (; x <= x2 && xIndex <= x2; x += stepx)
{
//插值当前点
Vectex p;
float t = (x - x1) / dx;
p = NewMath.Interp(v1, v2, t);
//画点坐标
xIndex = (int)(x + 0.5f);
if (xIndex >= device.width || xIndex <= 0 || yIndex <= 0 || yIndex >= device.height)
{
return;
}
if (p.rhw >= device.zBuffer[xIndex, yIndex])
{
device.zBuffer[xIndex, yIndex] = p.rhw;
float w = 1 / p.rhw;
if (device.lightMode == LightMode.ON)
{
Color lighlingColor = new Color(1, 1, 1);
lighlingColor = w * p.lightcolor;
if (device.renderState == RenderState.COLOR)
{
Color vertColor = new Color(1, 1, 1);
vertColor = w * p.color;
Color newColor = NewMath.Round(0.7f * vertColor + 0.3f * lighlingColor, 0, 1);
device.frameBuffer.SetPixel(xIndex, yIndex, Color.SystemColor(newColor));
}
if (device.renderState == RenderState.TEXTURE)
{
int uIndex;
int vIndex;
//目前只有点插值
int u = (int)(p.uvs.u * w * device.texWidth + 0.5f);
int v = (int)(p.uvs.v * w * device.texHeight + 0.5f);
uIndex = (int)NewMath.Round(u, 0, device.texWidth - 1);
vIndex = (int)NewMath.Round(v, 0, device.texHeight - 1);
//获取颜色
Color texColor = new Color(1, 1, 1);
texColor = new Color(device.textureBuffer.GetPixel(uIndex, vIndex));
Color newColor = NewMath.Round(0.7f * texColor + 0.3f * lighlingColor, 0, 1);
//画像素点
device.frameBuffer.SetPixel(xIndex, yIndex, Color.SystemColor(newColor));
}
}
else
{
if (device.renderState == RenderState.COLOR)
{
//用顶点颜色插值
Color vertColor = new Color(1, 1, 1);
vertColor = w * p.color;
device.frameBuffer.SetPixel(xIndex, yIndex, Color.SystemColor(vertColor));
}
if (device.renderState == RenderState.TEXTURE)
{
int uIndex;
int vIndex;
//目前只有点插值
int u = (int)(p.uvs.u * w * device.texWidth + 0.5f);
int v = (int)(p.uvs.v * w * device.texHeight + 0.5f);
uIndex = (int)NewMath.Round(u, 0, device.texWidth - 1);
vIndex = (int)NewMath.Round(v, 0, device.texHeight - 1);
//获取颜色
Color texColor = new Color(1, 1, 1);
texColor = new Color(device.textureBuffer.GetPixel(uIndex, vIndex));
//画像素点
device.frameBuffer.SetPixel(xIndex, yIndex, Color.SystemColor(texColor));
}
}
}
}
}