public void DrawTriangle_PS(Vertex v1, Vertex v2, Vertex v3, Color color, double Time, Vector3 viewerPos, bool blin = false)
{
if (v1.Position.y > v2.Position.y)
{
Swap(ref v1, ref v2);
}
if (v2.Position.y > v3.Position.y)
{
Swap(ref v2, ref v3);
}
if (v1.Position.y > v2.Position.y)
{
Swap(ref v1, ref v2);
}
var p1 = v1.Position;
var p2 = v2.Position;
var p3 = v3.Position;
var wp1 = v1.WorldPosition;
var wp2 = v2.WorldPosition;
var wp3 = v3.WorldPosition;
Vector3 lightPos = LP;
var data = new ScanLineDataPhong {
};
double dP1P2, dP1P3;
if (p2.y - p1.y > 0)
{
dP1P2 = (p2.x - p1.x) / (p2.y - p1.y);
}
else
{
dP1P2 = 0;
}
if (p3.y - p1.y > 0)
{
dP1P3 = (p3.x - p1.x) / (p3.y - p1.y);
}
else
{
dP1P3 = 0;
}
if (dP1P2 > dP1P3)
{
for (var y = (int)p1.y; y <= (int)p3.y; y++)
{
double gradient = (y - p1.y) / (double)(p3.y - p1.y);
data.currentWorldY = Interpolate(wp1.y, wp3.y, gradient);
data.currentY = y;
if (y < p2.y)
{
data.Na = v1.Normal;
data.Nb = v3.Normal;
data.Nc = v1.Normal;
data.Nd = v2.Normal;
ProcessScanLine_PS(data, v1, v3, v1, v2, color, lightPos, viewerPos, blin);
}
else
{
data.Na = v1.Normal;
data.Nb = v3.Normal;
data.Nc = v2.Normal;
data.Nd = v3.Normal;
ProcessScanLine_PS(data, v1, v3, v2, v3, color, lightPos, viewerPos, blin);
}
}
}
else
{
for (var y = (int)p1.y; y <= (int)p3.y; y++)
{
double gradient = (y - p1.y) / (double)(p3.y - p1.y);
data.currentWorldY = Interpolate(wp1.y, wp3.y, gradient);
data.currentY = y;
if (y < p2.y)
{
data.Na = v1.Normal;
data.Nb = v2.Normal;
data.Nc = v1.Normal;
data.Nd = v3.Normal;
ProcessScanLine_PS(data, v1, v2, v1, v3, color, lightPos, viewerPos, blin);
}
else
{
data.Na = v2.Normal;
data.Nb = v3.Normal;
data.Nc = v1.Normal;
data.Nd = v3.Normal;
ProcessScanLine_PS(data, v2, v3, v1, v3, color, lightPos, viewerPos, blin);
}
}
}
}
void ProcessScanLine_PS(ScanLineDataPhong data, Vertex A, Vertex B, Vertex C, Vertex D, Color color, Vector3 lightPosition, Vector3 viewerPosition, bool blin)
{
var pa = A.Position;
var pb = B.Position;
var pc = C.Position;
var pd = D.Position;
var wpa = A.WorldPosition;
var wpb = B.WorldPosition;
var wpc = C.WorldPosition;
var wpd = D.WorldPosition;
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)Interpolate(pa.x, pb.x, gradient1);
int ex = (int)Interpolate(pc.x, pd.x, gradient2);
int swx = (int)Interpolate(wpa.x, wpb.x, gradient1);
int ewx = (int)Interpolate(wpc.x, wpd.x, gradient2);
double z1 = Interpolate(pa.z, pb.z, gradient1);
double z2 = Interpolate(pc.z, pd.z, gradient2);
double wz1 = Interpolate(wpa.z, wpb.z, gradient1);
double wz2 = Interpolate(wpc.z, wpd.z, gradient2);
var sN = InterpolateVector(data.Na, data.Nb, gradient1);
var eN = InterpolateVector(data.Nc, data.Nd, gradient2);
for (var x = sx; x < ex; x++)
{
double gradient = (x - sx) / (double)(ex - sx);
var z = Interpolate(z1, z2, gradient);
var position = new Vector3(x, data.currentY, z);
var wx = Interpolate(swx, ewx, gradient);
var wy = data.currentWorldY;
var wz = Interpolate(wz1, wz2, gradient);
var wPosition = new Vector3(wx, wy, wz);
var N = InterpolateVector(sN, eN, gradient);
var NoL = Compute_NoL(wPosition, N, lightPosition);
byte r = 0, g = 0, b = 0;
if (blin)
{
var H = Compute_H(wPosition, viewerPosition, lightPosition);
H.Normalize();
var Nnorm = N;
Nnorm.Normalize();
var NoH = Vector3.Dot(Nnorm, H);
NoH = Math.Pow(NoH, alpha);
r = Limit(kd * color.R * NoL + ks * color.R * NoH);
g = Limit(kd * color.R * NoL + ks * color.R * NoH);
b = Limit(kd * color.R * NoL + ks * color.R * NoH);
}
else
{
var R = Compute_R(wPosition, N, lightPosition);
R.Normalize();
var V = viewerPosition - wPosition;
V.Normalize();
var RoV = OverZero(Vector3.Dot(R, V));
RoV = Math.Pow(RoV, alpha);
r = Limit(kd * color.R * NoL + ks * color.R * RoV);
g = Limit(kd * color.R * NoL + ks * color.R * RoV);
b = Limit(kd * color.R * NoL + ks * color.R * RoV);
}
var shadedColor = Color.FromArgb(color.A, r, g, b);
DrawPoint(position, shadedColor);
}
}