private void AddSun(RaycastingParameters parameters, Vector4 position, Vector3 lightPosition, Matrix4x4 viewMatrix,
float s, int width, float aspect, int height)
{
var lightDirection = position - new Vector4(lightPosition, 1.0f);
var lightDirectionView = Vector4.Transform(lightDirection, viewMatrix);
if (lightDirectionView.Z < 0)
{
return;
}
lightDirectionView /= lightDirectionView.Z;
var xa = (lightDirectionView.X / s + 0.5f) * width;
var ya = (lightDirectionView.Y / -s * aspect + -0.5f) * -height;
if (xa < 0 || xa >= width || ya < 0 || ya >= height)
{
return;
}
for (int i = -parameters.SunRadius; i <= parameters.SunRadius; i++)
{
for (int j = -parameters.SunRadius; j <= parameters.SunRadius; j++)
{
if (i * i + j * j < parameters.SunRadius * parameters.SunRadius)
{
_directBitmap.SetPixel((int)xa + i, (int)ya + j, new MyColor(255, 255, 255));
}
}
}
}
public void Draw(RaycastingParameters parameters)
{
var width = _directBitmap.Width;
var height = _directBitmap.Height;
using (var g = Graphics.FromImage(_directBitmap.Bitmap))
{
g.Clear(Color.Black);
}
var viewMatrix = _camera.ViewMatrix;
Matrix4x4.Invert(viewMatrix, out var invViewMatrix);
var position = _camera.Position;
float aspect = (float)height / width;
float s = (float)(-2.0 * Math.Tan(_fov * 0.5));
var rx2 = parameters.EllipseX * parameters.EllipseX;
var ry2 = parameters.EllipseY * parameters.EllipseY;
var rz2 = parameters.EllipseZ * parameters.EllipseZ;
var ellipse4 = new Vector4(1.0f / rx2, 1.0f / ry2, 1.0f / rz2, -1.0f);
var posEllips = Vector4.Multiply(position, ellipse4);
var constant = Vector4.Dot(posEllips, position);
var direction = new Vector4(0.0f, 0.0f, 1.0f, 0.0f);
var lightPosition = new Vector3(parameters.LightPositionX, parameters.LightPositionY,
parameters.LightPositionZ);
for (int y = 0; y < height; ++y)
{
direction.Y = -((float)y / height - 0.5f) * s * aspect;
for (int x = 0; x < width; ++x)
{
direction.X = ((float)x / width - 0.5f) * s;
var rotatedDirection = Vector4.Transform(direction, invViewMatrix);
var squaredCoef = Vector4.Dot(Vector4.Multiply(rotatedDirection, ellipse4), rotatedDirection);
var linearCoef = 2 * Vector4.Dot(rotatedDirection, posEllips);
var preRoot = linearCoef * linearCoef - 4 * squaredCoef * constant;
if (!(preRoot >= 0))
{
continue;
}
var sgn = squaredCoef > 0 ? 1.0 : -1.0;
var coef = (float)((sgn * Math.Sqrt(preRoot) - linearCoef) / (2.0 * squaredCoef));
if (coef > 0)
{
continue;
}
var pointPosition = position + coef * rotatedDirection;
var pointPosition3 = new Vector3(pointPosition.X, pointPosition.Y, pointPosition.Z);
var rotatedDirection3 = new Vector3(rotatedDirection.X, rotatedDirection.Y, rotatedDirection.Z);
_directBitmap.SetPixel(x, height - 1 - y,
GetPixelColor(pointPosition3, rotatedDirection3, lightPosition, parameters));
}
}
if (_directBitmap.Width > 500)
{
AddSun(parameters, position, lightPosition, viewMatrix, s, width, aspect, height);
}
}
private static MyColor GetPixelColor(Vector3 pointPosition, Vector3 lookDirection, Vector3 lightPosition, RaycastingParameters parameters)
{
var lightDirection = Vector3.Normalize(lightPosition - pointPosition);
var rx2 = parameters.EllipseX * parameters.EllipseX;
var ry2 = parameters.EllipseY * parameters.EllipseY;
var rz2 = parameters.EllipseZ * parameters.EllipseZ;
var normal = pointPosition;
normal.X /= rx2;
normal.Y /= ry2;
normal.Z /= rz2;
normal = Vector3.Normalize(normal);
double cos = Vector3.Dot(normal, lightDirection);
if (cos < 0)
{
cos = 0;
}
var distR = (byte)(255 * cos * parameters.DistributedCoef);
var distG = (byte)(255 * cos * parameters.DistributedCoef);
var rVector = Vector3.Normalize(2 * Vector3.Dot(normal, lightDirection) * normal - lightDirection);
var toObsVector = Vector3.Normalize(lookDirection);
var specularDot = Vector3.Dot(rVector, toObsVector);
if (specularDot < 0)
{
specularDot = 0;
}
var specular = Math.Pow(specularDot, parameters.CosinusExponent) * 256 * parameters.SpecularCoef;
var r = distR + specular > 255 ? (byte)255 : (byte)(distR + specular);
var g = distG + specular > 255 ? (byte)255 : (byte)(distG + specular);
const byte ambient = 0;
var b = ambient + (byte)specular > 255 ? (byte)255 : (byte)(ambient + specular);
return(new MyColor(r, g, b));
}
