private Color DiffuseShading(Sphere sphere, SinglePoint viewerPoint, SinglePoint lightPoint, double dx, double dy, double dz, double a, double b, double c, int width, int height)
{
double x, y, z, t;
Vector3D normalVector = new Vector3D();
Vector3D lightVector = new Vector3D();
t = (-b - Math.Sqrt(b * b - 4 * a * c)) / (2 * a);
x = viewerPoint.x + t * dx;
y = viewerPoint.y + t * dy;
z = viewerPoint.z + t * dz;
//Unit normal vector
normalVector.X = ((x - sphere.Center.x) / sphere.Radius);
normalVector.Y = (y - sphere.Center.y) / sphere.Radius;
normalVector.Z = (z - sphere.Center.z) / sphere.Radius;
//Vector from normal to the Light
lightVector.X = lightPoint.x - x;
lightVector.Y = lightPoint.y - y;
lightVector.Z = lightPoint.z - z;
//constants
double kd = 0.8;
double ka = 0.2;
double fctr = Vector3D.DotProduct(normalVector, lightVector);
Color resultColor = new Color();
resultColor.R = (byte)(ka * sphere.R + kd * fctr * sphere.R);
resultColor.G = (byte)(ka * sphere.G + kd * fctr * sphere.G);
resultColor.B = (byte)(ka * sphere.B + kd * fctr * sphere.B);
return(resultColor);
}
private void test()
{
Sphere sampleSphere = new Sphere();
sampleSphere.Radius = 10;
sampleSphere.SpehereColor = Colors.Red;
sampleSphere.R = 255;
sampleSphere.G = 0;
sampleSphere.B = 0;
sampleSphere.Center = new SinglePoint();
sampleSphere.Center.x = 5170;
sampleSphere.Center.y = 60;
sampleSphere.Center.z = 8;
SinglePoint pointOfTheViewer = new SinglePoint();
pointOfTheViewer.x = 100;
pointOfTheViewer.y = 80;
pointOfTheViewer.z = 1;
int canvasWidth = 500;
int canvasHeight = 300;
int[,] intersections = new int[canvasWidth, canvasHeight];
SphereInterscetionCheck(sampleSphere, pointOfTheViewer, canvasWidth, canvasHeight);
}
/* A sphere is given by its center (cx, cy, cz), its radius R, and its color (SR, SG, SB).
* line segment (ray) is given by its endpoints: P0 = (x0, y0, z0) and P1 = (x1, y1, z1).
* To find visible spheres, set P0 = viewer’s coordinates, VP = (VPx, VPy, VPz) and let P1 run through
* all the points (x1, y1, 0) where (x1, y1) is a pixel in the display area.
*/
private void SphereInterscetionCheck(Sphere sphere, SinglePoint viewerPoint, int width, int height)
{
double dx, dy, dz, a, b, c, delta;
SinglePoint lightPoint = new SinglePoint();
lightPoint.x = 10;
lightPoint.y = 15;
lightPoint.z = 5;
int[,] resultOfIntersection = new int[width, height];
for (int i = 0; i < width; i++)
{
for (int j = 0; j < height; j++)
{
dx = i - viewerPoint.x;
dy = j - viewerPoint.y;
dz = 0 - viewerPoint.z;
a = dx * dx + dy * dy + dz * dz;
b = 2 * dx * (viewerPoint.z - sphere.Center.x) + 2 * dy * (viewerPoint.y - sphere.Center.y) + 2 * dz * (viewerPoint.z - sphere.Center.z);
c = sphere.Center.x * sphere.Center.x + sphere.Center.y * sphere.Center.y + sphere.Center.z * sphere.Center.z + viewerPoint.x * viewerPoint.x + viewerPoint.y * viewerPoint.y + viewerPoint.z * viewerPoint.z - 2 * (sphere.Center.x * viewerPoint.x + sphere.Center.y * viewerPoint.y + sphere.Center.z * viewerPoint.z) - sphere.Radius * sphere.Radius;
delta = b * b - 4 * a * c;
if (delta < 0) //Findinghadowws
{
DrawPixel(i, j, Colors.Black);
}
else if (delta == 0)
{
DrawPixel(i, j, (DiffuseShading(sphere, viewerPoint, lightPoint, dx, dy, dz, a, b, c, width, height)));//resultOfIntersection[i, j] = 1;
}
else
{
DrawPixel(i, j, (DiffuseShading(sphere, viewerPoint, lightPoint, dx, dy, dz, a, b, c, width, height)));//resultOfIntersection[i, j] = 2;
}
}
}
}