public void DrawTriangle(MyPoint v1, MyPoint v2, MyPoint v3, Vector4 color)
{
if (v1.coords2d.Y > v2.coords2d.Y)
{
Swap <MyPoint>(ref v1, ref v2);
}
if (v2.coords2d.Y > v3.coords2d.Y)
{
Swap <MyPoint>(ref v2, ref v3);
}
if (v1.coords2d.Y > v2.coords2d.Y)
{
Swap <MyPoint>(ref v1, ref v2);
}
Vector4 p1 = v1.coords2d;
Vector4 p2 = v2.coords2d;
Vector4 p3 = v3.coords2d;
Vector4 lightPos2 = new Vector4(0, 10, 10, 1);
// Light position
Vector4 lightPos = new Vector4(objects[1].pointList[5]._currentCoords.X - 0.1f, objects[1].pointList[5]._currentCoords.Y - 0.1f, objects[1].pointList[5]._currentCoords.Z - 0.1f, 1);
List <Vector4> lights = new List <Vector4>();
lights.Add(lightPos);
lights.Add(lightPos2);
// computing the cos of the angle between the light vector and the normal vector
// it will return a value between 0 and 1 that will be used as the intensity of the color
float nl1 = 0.0f, nl2 = 0.0f, nl3 = 0.0f;
if (radioButton4.Checked == true)
{
nl1 = CalculateLight(lights, v1);
nl2 = CalculateLight(lights, v2);
nl3 = CalculateLight(lights, v3);
}
var data = new ScanLineData {
};
float dP1P2, dP1P3;
dP1P2 = (p2.Y - p1.Y > 0) ? (p2.X - p1.X) / (p2.Y - p1.Y) : 0;
dP1P3 = (p3.Y - p1.Y > 0) ? (p3.X - p1.X) / (p3.Y - p1.Y) : 0;
// Light position
// first triangle
if (dP1P2 > dP1P3)
{
for (int y = (int)p1.Y; y <= (int)p3.Y; y++)
{
data.currentY = y;
if (y < p2.Y)
{
data.ndotla = nl1;
data.ndotlb = nl3;
data.ndotlc = nl1;
data.ndotld = nl2;
data.normalA = v1.normal;
data.normalB = v3.normal;
data.normalC = v1.normal;
data.normalD = v2.normal;
ProcessScanLine(data, v1, v3, v1, v2, color);
}
else
{
data.ndotla = nl1;
data.ndotlb = nl3;
data.ndotlc = nl2;
data.ndotld = nl3;
data.normalA = v1.normal;
data.normalB = v3.normal;
data.normalC = v2.normal;
data.normalD = v3.normal;
ProcessScanLine(data, v1, v3, v2, v3, color);
}
}
}
// second triangle
else
{
for (int y = (int)p1.Y; y <= (int)p3.Y; y++)
{
data.currentY = y;
if (y < p2.Y)
{
data.ndotla = nl1;
data.ndotlb = nl2;
data.ndotlc = nl1;
data.ndotld = nl3;
data.normalA = v1.normal;
data.normalB = v2.normal;
data.normalC = v1.normal;
data.normalD = v3.normal;
ProcessScanLine(data, v1, v2, v1, v3, color);
}
else
{
data.ndotla = nl2;
data.ndotlb = nl3;
data.ndotlc = nl1;
data.ndotld = nl3;
data.normalA = v2.normal;
data.normalB = v3.normal;
data.normalC = v1.normal;
data.normalD = v3.normal;
ProcessScanLine(data, v2, v3, v1, v3, color);
}
}
}
}
void ProcessScanLine(ScanLineData data, MyPoint va, MyPoint vb, MyPoint vc, MyPoint vd, Vector4 color)
{
Vector4 pa = va.coords2d;
Vector4 pb = vb.coords2d;
Vector4 pc = vc.coords2d;
Vector4 pd = vd.coords2d;
// Thanks to current Y, we can compute the gradient to compute others values like
// the starting X (sx) and ending X (ex) to draw between
// if pa.Y == pb.Y or pc.Y == pd.Y, gradient is forced to 1
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);
// starting Z & ending Z
float z1 = Interpolate(pa.Z, pb.Z, gradient1);
float z2 = Interpolate(pc.Z, pd.Z, gradient2);
float real_z1 = Interpolate(va._currentCoords.Z, vb._currentCoords.Z, gradient1);
float real_z2 = Interpolate(vc._currentCoords.Z, vd._currentCoords.Z, gradient1);
Vector4 Vsnl = new Vector4(), Venl = new Vector4();
float snl = 0.0f, enl = 0.0f;
if (radioButton4.Checked == true)
{
snl = Interpolate(data.ndotla, data.ndotlb, gradient1);
enl = Interpolate(data.ndotlc, data.ndotld, gradient2);
}
else if (radioButton5.Checked == true)
{
Vsnl = Interpolate(data.normalA, data.normalB, gradient1);
Venl = Interpolate(data.normalC, data.normalD, gradient2);
}
Vector4 lightPos2 = new Vector4(0, 10, 10, 1);
// Light position
Vector4 lightPos = new Vector4(objects[1].pointList[5]._currentCoords.X - 0.01f, objects[1].pointList[5]._currentCoords.Y - 0.01f, objects[1].pointList[5]._currentCoords.Z - 0.011f, 1);
List <Vector4> lights = new List <Vector4>();
lights.Add(lightPos);
lights.Add(lightPos2);
// drawing a line from left (sx) to right (ex)
for (var x = sx; x < ex; x++)
{
float gradient = (x - sx) / (float)(ex - sx);
var z = Interpolate(z1, z2, gradient);
var real_z = Interpolate(real_z1, real_z2, gradient);
Vector4 Vndotl;
float ndotl = 0.0f;
if (radioButton4.Checked == true)
{
ndotl = Interpolate(snl, enl, gradient);
}
else if (radioButton5.Checked == true)
{
Vndotl = Interpolate(Vsnl, Venl, gradient);
ndotl = CalculateLight(lights, new Vector4(x / pictureBox1.Width, data.currentY / pictureBox1.Height, real_z, 1), Vndotl);
}
float ndotl1 = Interpolate(snl, enl, gradient);
// changing the color value using the cosine of the angle
// between the light vector and the normal vector
DrawPoint(new Vector4(x, data.currentY, z, 1), color * ndotl);
}
}