public static Color Lerp(Color c1, Color c2, float t)
{
int r = (int)MathUtility.Lerp(c1.R, c2.R, t);
int g = (int)MathUtility.Lerp(c1.G, c2.G, t);
int b = (int)MathUtility.Lerp(c1.B, c2.B, t);
return(ColorUtility.ToColor(r, g, b));
}
public static Vector Lerp(Vector a, Vector b, float t)
{
Vector vec = Vector.Zero;
vec.x = MathUtility.Lerp(a.x, b.x, t);
vec.y = MathUtility.Lerp(a.y, b.y, t);
vec.z = MathUtility.Lerp(a.z, b.z, t);
return(vec);
}
public static Vertex LerpVertexInScreenSpace(Vertex v1, Vertex v2, float t)
{
Vertex vert = new Vertex();
vert.pos = MathUtility.Lerp(v1.pos, v2.pos, t);
vert.color = ColorUtility.Lerp(v1.color, v2.color, t);
vert.u = MathUtility.Lerp(v1.u, v2.u, t);
vert.v = MathUtility.Lerp(v1.v, v2.v, t);
vert.onePerZ = MathUtility.Lerp(v1.onePerZ, v2.onePerZ, t);
return(vert);
}
public void DrawScanLine(Vertex left, Vertex right)
{
Texture2D texture = Application.Texture;
int length = (int)(right.pos.x - left.pos.x);
float onePerLength = length == 0 ? 0 : 1f / length;
int y = (int)left.pos.y;
for (int i = (int)left.pos.x; i < right.pos.x; i++)
{
float t = (i - left.pos.x) * onePerLength;
float onePerZ = MathUtility.Lerp(left.onePerZ, right.onePerZ, t);
if (false) //TODO: 深度测试
{
continue;
}
//x'、y'与1/z是线性关系，u/z、v/z 与 x’、y’也是线性关系
//所以可以对 1/z关于 x’、y'插值得到 1/z’
//然后对u/z、v/z 关于 x’、y’插值得到 u'/z' 和 v'/z'
// u'/z' 和 v'/z'除以 1/z’得出正确的u’、v'
float tz = 1 / onePerZ;
float u = MathUtility.Lerp(left.u, right.u, t) * tz * (texture.width - 1);
float v = MathUtility.Lerp(left.v, right.v, t) * tz * (texture.height - 1);
int uIndex = (int)Math.Round(u, MidpointRounding.AwayFromZero);
int vIndex = (int)Math.Round(v, MidpointRounding.AwayFromZero);
Color color = Color.White;
//if (uIndex > 128)
//{
// color = Color.Yellow;
// if (vIndex > 128)
// {
// color = Color.YellowGreen;
// }
//}
//else if (vIndex > 128)
//{
// color = Color.SlateBlue;
//}
color = texture.ReadTexture(uIndex, vIndex);
DrawPoint(i, y, color);
}
}