public void DrawTriangle(Vector3 v1, Vector3 v2, Vector3 v3, Color frontFaceColor, Color backFaceColor, float[,] matrix)
{
v1 = v1.Transform(matrix);
v2 = v2.Transform(matrix);
v3 = v3.Transform(matrix);
Vector3 normal = Vector3.Cross(v1 - v2, v1 - v3);
normal.Normalize();
//set color or return for culling
Color color = frontFaceColor;
if (normal.Z > 0)
color = backFaceColor;
if (color == Color.Transparent)
return;
if (EnableShading)
{
float shading = 0.5f + 0.5f * Math.Abs(normal.Z);
color.R = (byte)(color.R * shading);
color.G = (byte)(color.G * shading);
color.B = (byte)(color.B * shading);
}
Vector2 min = new Vector2();
Vector2 max = new Vector2();
min.X = Math.Min(v1.X, Math.Min(v2.X, v3.X));
min.Y = Math.Min(v1.Y, Math.Min(v2.Y, v3.Y));
max.X = Math.Max(v1.X, Math.Max(v2.X, v3.X));
max.Y = Math.Max(v1.Y, Math.Max(v2.Y, v3.Y));
min = min.ClampVector2(Vector2.Zero, ScreenSize.ToVector2());
max = max.ClampVector2(Vector2.Zero, ScreenSize.ToVector2());
Vector3[] verts = new Vector3[3] { v1, v2, v3 };
for (int yp = (int)min.Y; yp < (int)max.Y; yp++)
{
List<Vector3> intersections = new List<Vector3>();
//voor alle lijnen van de triangle, vind alle intersecties (als het goed is altijd 2)
for (int l = 0; l < 3; l++)
{
Vector3 vert1, vert2;
vert1 = verts[l];
vert2 = verts[(l + 1) % 3];
float ymin, ymax;
ymin = Math.Min(vert1.Y, vert2.Y);
ymax = Math.Max(vert1.Y, vert2.Y);
if (yp > ymin && yp < ymax)//check of yp tussen de y-en van de vertices ligt, zo ja, intersectie
{
float xSlope = (vert2.X - vert1.X) / (vert2.Y - vert1.Y);
float xIntersect = vert1.X + xSlope * (yp - vert1.Y);
float zSlope = (vert2.Z - vert1.Z) / (vert2.Y - vert1.Y);
float zIntersect = vert1.Z + zSlope * (yp - vert1.Y);
intersections.Add(new Vector3((int)xIntersect, yp, zIntersect));
}
}
//vul scanline
if (intersections.Count > 1)
{
Vector3 pStart, pEnd;
if (intersections[0].X < intersections[1].X) { pStart = intersections[0]; pEnd = intersections[1]; }
else
{ pStart = intersections[1]; pEnd = intersections[0]; }
//vul de rij met pixels
for (int xp = MathHelper.Clamp((int)pStart.X, 0, ScreenSize.X); xp < MathHelper.Clamp(pEnd.X, 0, ScreenSize.X); xp++)
{
float zSlope = (pEnd.Z - pStart.Z) / (pEnd.X - pStart.X);
float zCurrent = pStart.Z + zSlope * (xp - pStart.X);
//DrawPoint(new Vector3(xp, yp, zCurrent), color, Matrix.GetIdentity());
if (zCurrent < zBuffer[xp, yp] && zCurrent > ZNear)
{
screen[xp, yp] = color;
zBuffer[xp, yp] = zCurrent;
}
}
}
}
}