public Device(Panel canvas)
{
this.Canvas = canvas;
canvas.Paint += Redraw;
PhongShadingModel = new PhongShadingModel();
}
void ProcessScanLinePhong(int y, Vertex pa, Vertex pb, Vertex pc, Vertex pd, Color color)
{
const double epsilon = 0.0001;
var gradient1 = Math.Abs(pa.ScreenPosition.Y - pb.ScreenPosition.Y) > epsilon ? (y - pa.ScreenPosition.Y) / (pb.ScreenPosition.Y - pa.ScreenPosition.Y) : 1;
var gradient2 = Math.Abs(pc.ScreenPosition.Y - pd.ScreenPosition.Y) > epsilon ? (y - pc.ScreenPosition.Y) / (pd.ScreenPosition.Y - pc.ScreenPosition.Y) : 1;
int sx = (int)MathHelpers.Interpolate(pa.ScreenPosition.X, pb.ScreenPosition.X, gradient1);
int ex = (int)MathHelpers.Interpolate(pc.ScreenPosition.X, pd.ScreenPosition.X, gradient2);
// starting Z & ending Z
double z1 = MathHelpers.Interpolate(pa.ScreenPosition.Z, pb.ScreenPosition.Z, gradient1);
double z2 = MathHelpers.Interpolate(pc.ScreenPosition.Z, pd.ScreenPosition.Z, gradient2);
double sx_world = MathHelpers.Interpolate(pa.Position.X, pb.Position.X, gradient1);
double ex_world = MathHelpers.Interpolate(pc.Position.X, pd.Position.X, gradient2);
double y1_world = MathHelpers.Interpolate(pa.Position.Y, pb.Position.Y, gradient1);
double y2_world = MathHelpers.Interpolate(pc.Position.Y, pd.Position.Y, gradient2);
double z1_world = MathHelpers.Interpolate(pa.Position.Z, pb.Position.Z, gradient1);
double z2_world = MathHelpers.Interpolate(pc.Position.Z, pd.Position.Z, gradient2);
var normal1 = MathHelpers.Interpolate(pa.Normal, pb.Normal, gradient1);
var normal2 = MathHelpers.Interpolate(pc.Normal, pd.Normal, gradient2);
// drawing a line from left (sx) to right (ex)
if (ex < sx)
{
Utils.Swap(ref sx, ref ex);
Utils.Swap(ref gradient1, ref gradient2);
Utils.Swap(ref z1, ref z2);
Utils.Swap(ref sx_world, ref ex_world);
Utils.Swap(ref y1_world, ref y2_world);
Utils.Swap(ref z1_world, ref z2_world);
Utils.Swap(ref normal1, ref normal2);
}
for (var x = sx; x < ex; x++)
{
float gradient = (x - sx) / (float)(ex - sx);
var z = MathHelpers.Interpolate(z1, z2, gradient);
var x_world = MathHelpers.Interpolate(sx_world, ex_world, gradient);
var y_world = MathHelpers.Interpolate(y1_world, y2_world, gradient);
var z_world = MathHelpers.Interpolate(z1_world, z2_world, gradient);
var normal = MathHelpers.Interpolate(normal1, normal2, gradient);
normal = normal.Versor();
var lightCol = PhongShadingModel.ComputeIntensityAt(
new Vertex
{
Normal = normal,
Position = new Vector4(x_world, y_world, z_world, 1)
},
CurrentCamera,
color);
DrawPoint(new Vector3(x, y, z), lightCol);
}
}