public void ProcessScanLine(ScanLineData data, Vertex va, Vertex vb, Vertex vc, Vertex vd, Color4 color, Texture texture)
{
var pa = va.Coordinates;
var pb = vb.Coordinates;
var pc = vc.Coordinates;
var pd = vd.Coordinates;
var gradient1 = pa.Y != pb.Y ? (data.CurrentY - pa.Y) / (pb.Y - pa.Y) : 1;
var gradient2 = pc.Y != pd.Y ? (data.CurrentY - pc.Y) / (pd.Y - pc.Y) : 1;
int sx = (int)MathLib.Interpolate(pa.X, pb.X, gradient1);
int ex = (int)MathLib.Interpolate(pc.X, pd.X, gradient2);
float z1 = MathLib.Interpolate(pa.Z, pb.Z, gradient1);
float z2 = MathLib.Interpolate(pc.Z, pd.Z, gradient2);
var snl = MathLib.Interpolate(data.NDotla, data.NDotlb, gradient1);
var enl = MathLib.Interpolate(data.NDotlc, data.NDotld, gradient2);
var su = MathLib.Interpolate(data.ua, data.ub, gradient1);
var eu = MathLib.Interpolate(data.uc, data.ud, gradient2);
var sv = MathLib.Interpolate(data.va, data.vb, gradient1);
var ev = MathLib.Interpolate(data.vc, data.vd, gradient2);
for (int index = sx; index < ex; index++)
{
var grad = (index - sx) / (float)(ex - sx);
var z = MathLib.Interpolate(z1, z2, grad);
var ndotl = MathLib.Interpolate(snl, enl, grad);
var u = MathLib.Interpolate(su, eu, grad);
var v = MathLib.Interpolate(sv, ev, grad);
var textureColor = texture?.Map(u, v) ?? new Color4(1, 1, 1, 1);
DrawPoint(index, data.CurrentY, z, new Color4(
color.Red * ndotl * textureColor.Red,
color.Green * ndotl * textureColor.Green,
color.Blue * ndotl * textureColor.Blue,
color.Alpha * textureColor.Alpha));
}
}
public void DrawTriangle(Vertex v0, Vertex v1, Vertex v2, Color4 color, Texture texture)
{
if (v0.Coordinates.Y > v1.Coordinates.Y)
{
var temp = v1;
v1 = v0;
v0 = temp;
}
if (v1.Coordinates.Y > v2.Coordinates.Y)
{
var temp = v1;
v1 = v2;
v2 = temp;
}
if (v0.Coordinates.Y > v1.Coordinates.Y)
{
var temp = v1;
v1 = v0;
v0 = temp;
}
var p0 = v0.Coordinates;
var p1 = v1.Coordinates;
var p2 = v2.Coordinates;
//var vnFace = (v0.Normal + v1.Normal + v2.Normal) / 3f;
//var centerPoint = (v0.WorldCoordinates + v1.WorldCoordinates + v2.WorldCoordinates) / 3f;
//var ndotl = MathLib.ComputeNDotL(centerPoint, vnFace, lightPos);
//var data = new ScanLineData{NDotla = ndotl};
//var cent = (v0.Coordinates + v1.Coordinates + v2.Coordinates) / 3f;
//DrawBresenhamLine(cent, cent + vnFace * 10);
float nl0 = MathLib.ComputeNDotL(v0.WorldCoordinates, v0.Normal, lightPos);
float nl1 = MathLib.ComputeNDotL(v1.WorldCoordinates, v1.Normal, lightPos);
float nl2 = MathLib.ComputeNDotL(v2.WorldCoordinates, v2.Normal, lightPos);
var data = new ScanLineData();
float dP0P1, dP0P2;
if (p1.Y - p0.Y > 0)
{
dP0P1 = (p1.X - p0.X) / (p1.Y - p0.Y);
}
else
{
dP0P1 = 0;
}
if (p2.Y - p0.Y > 0)
{
dP0P2 = (p2.X - p0.X) / (p2.Y - p0.Y);
}
else
{
dP0P2 = 0;
}
if (dP0P1 > dP0P2)
{
for (var y = (int)p0.Y; y <= (int)p2.Y; y++)
{
data.CurrentY = y;
if (y < p1.Y)
{
data.NDotla = nl0;
data.NDotlb = nl2;
data.NDotlc = nl0;
data.NDotld = nl1;
data.ua = v0.TextureCoordinates.X;
data.ub = v2.TextureCoordinates.X;
data.uc = v0.TextureCoordinates.X;
data.ud = v1.TextureCoordinates.X;
data.va = v0.TextureCoordinates.Y;
data.vb = v2.TextureCoordinates.Y;
data.vc = v0.TextureCoordinates.Y;
data.vd = v1.TextureCoordinates.Y;
ProcessScanLine(data, v0, v2, v0, v1, color, texture);
}
else
{
data.NDotla = nl0;
data.NDotlb = nl2;
data.NDotlc = nl1;
data.NDotld = nl2;
data.ua = v0.TextureCoordinates.X;
data.ub = v2.TextureCoordinates.X;
data.uc = v1.TextureCoordinates.X;
data.ud = v2.TextureCoordinates.X;
data.va = v0.TextureCoordinates.Y;
data.vb = v2.TextureCoordinates.Y;
data.vc = v1.TextureCoordinates.Y;
data.vd = v2.TextureCoordinates.Y;
ProcessScanLine(data, v0, v2, v1, v2, color, texture);
}
}
}
else
{
for (var y = (int)p0.Y; y <= (int)p2.Y; y++)
{
data.CurrentY = y;
if (y < p1.Y)
{
data.NDotla = nl0;
data.NDotlb = nl1;
data.NDotlc = nl0;
data.NDotld = nl2;
data.ua = v0.TextureCoordinates.X;
data.ub = v1.TextureCoordinates.X;
data.uc = v0.TextureCoordinates.X;
data.ud = v2.TextureCoordinates.X;
data.va = v0.TextureCoordinates.Y;
data.vb = v1.TextureCoordinates.Y;
data.vc = v0.TextureCoordinates.Y;
data.vd = v2.TextureCoordinates.Y;
ProcessScanLine(data, v0, v1, v0, v2, color, texture);
}
else
{
data.NDotla = nl1;
data.NDotlb = nl2;
data.NDotlc = nl0;
data.NDotld = nl2;
data.ua = v1.TextureCoordinates.X;
data.ub = v2.TextureCoordinates.X;
data.uc = v0.TextureCoordinates.X;
data.ud = v2.TextureCoordinates.X;
data.va = v1.TextureCoordinates.Y;
data.vb = v2.TextureCoordinates.Y;
data.vc = v0.TextureCoordinates.Y;
data.vd = v2.TextureCoordinates.Y;
ProcessScanLine(data, v1, v2, v0, v2, color, texture);
}
}
}
}