public unsafe static void RenderTriangle(Pixbuf pb, ColoredPoint cp0, ColoredPoint cp1, ColoredPoint cp2)
{
int x0 = cp0.X;
int y0 = cp0.Y;
int x1 = cp1.X;
int y1 = cp1.Y;
int x2 = cp2.X;
int y2 = cp2.Y;
// Fij(x, y, xi, xj, yi, yj) = (yi - yj) * x + (xj - xi) * y + xi * yj - xj * yi
float d_a = (y1 - y2) * x0 + (x1 - x2) * y0 + x1 * y2 - x2 * y1;
float d_b = (y2 - y0) * x1 + (x0 - x2) * y1 + x2 * y0 - x0 * y2;
float d_c = (y0 - y1) * x2 + (x1 - x0) * y2 + x0 * y1 - x1 * y0;
float a_i = y1 - y2;
float a_j = x2 - x1;
float a_k = x1 * y2 - x2 * y1;
float b_i = y2 - y0;
float b_j = x0 - x2;
float b_k = x2 * y0 - x0 * y2;
float c_i = y0 - y1;
float c_j = x1 - x0;
float c_k = x0 * y1 - x1 * y0;
int ymin = Math.Min(Math.Min(y0, y1), y2);
int ymax = Math.Max(Math.Max(y0, y1), y2);
int xmin = Math.Min(Math.Min(x0, x1), x2);
int xmax = Math.Max(Math.Max(x0, x1), x2);
byte *bptr = (byte *)pb.Pixels.ToPointer();
byte *p;
float alpha, beta, gamma;
for (int y = ymin; y < ymax; y++)
{
for (int x = xmin; x < xmax; x++)
{
alpha = (a_i * x + a_j * y + a_k) / d_a;
beta = (b_i * x + b_j * y + b_k) / d_b;
gamma = (c_i * x + c_j * y + c_k) / d_c;
if (alpha >= 0 && beta >= 0 && gamma >= 0)
{
p = bptr + y * pb.Rowstride + x * pb.NChannels;
p[0] = (byte)((cp0.R * alpha + cp1.R * beta + cp2.R * gamma) * 255); // r
p[1] = (byte)((cp0.G * alpha + cp1.G * beta + cp2.G * gamma) * 255); // g
p[2] = (byte)((cp0.B * alpha + cp1.B * beta + cp2.B * gamma) * 255); // b
p[3] = (byte)((cp0.A * alpha + cp1.A * beta + cp2.A * gamma) * 255); // a
}
}
}
}
public static unsafe void RenderTriangle(Pixbuf pb, ColoredPoint cp0, ColoredPoint cp1, ColoredPoint cp2)
{
int x0 = cp0.X;
int y0 = cp0.Y;
int x1 = cp1.X;
int y1 = cp1.Y;
int x2 = cp2.X;
int y2 = cp2.Y;
// Fij(x, y, xi, xj, yi, yj) = (yi - yj) * x + (xj - xi) * y + xi * yj - xj * yi
float d_a = (y1 - y2) * x0 + (x1 - x2) * y0 + x1 * y2 - x2 * y1;
float d_b = (y2 - y0) * x1 + (x0 - x2) * y1 + x2 * y0 - x0 * y2;
float d_c = (y0 - y1) * x2 + (x1 - x0) * y2 + x0 * y1 - x1 * y0;
float a_i = y1 - y2;
float a_j = x2 - x1;
float a_k = x1 * y2 - x2 * y1;
float b_i = y2 - y0;
float b_j = x0 - x2;
float b_k = x2 * y0 - x0 * y2;
float c_i = y0 - y1;
float c_j = x1 - x0;
float c_k = x0 * y1 - x1 * y0;
int ymin = Math.Min(Math.Min(y0, y1), y2);
int ymax = Math.Max(Math.Max(y0, y1), y2);
int xmin = Math.Min(Math.Min(x0, x1), x2);
int xmax = Math.Max(Math.Max(x0, x1), x2);
byte* bptr = (byte*)pb.Pixels.ToPointer();
byte* p;
float alpha, beta, gamma;
for (int y = ymin; y < ymax; y++)
for (int x = xmin; x < xmax; x++)
{
alpha = (a_i * x + a_j * y + a_k) / d_a;
beta = (b_i * x + b_j * y + b_k) / d_b;
gamma = (c_i * x + c_j * y + c_k) / d_c;
if (alpha >= 0 && beta >= 0 && gamma >= 0)
{
p = bptr + y * pb.Rowstride + x * pb.NChannels;
p[0] = (byte)((cp0.R * alpha + cp1.R * beta + cp2.R * gamma) * 255); // r
p[1] = (byte)((cp0.G * alpha + cp1.G * beta + cp2.G * gamma) * 255); // g
p[2] = (byte)((cp0.B * alpha + cp1.B * beta + cp2.B * gamma) * 255); // b
p[3] = (byte)((cp0.A * alpha + cp1.A * beta + cp2.A * gamma) * 255); // a
}
}
}
