private Vector3 CalcColor(Ray ray, int pathTracingLimit, int reflectionLimit)
{
var rgb = Vector3.Zero;
var hitPoint = FindClosestHitPoint(ray);
if (hitPoint != null)
{
var sphere = hitPoint.Sphere;
var rayVecNorm = Vector3.Normalize(hitPoint.Ray.DirectionVec);
var rayVec = (hitPoint.Ray.Lambda * rayVecNorm) + (-rayVecNorm * 0.001f) /* nudging..? */;
var hitPointVec = hitPoint.Ray.StartVec + rayVec;
var nVecNorm = Vector3.Normalize(hitPointVec - hitPoint.Sphere.Center);
var material = sphere.CalcColor(hitPointVec);
if (!PathTracing)
{
if (sphere.Brightness > 0)
{
rgb += material * sphere.Brightness;
}
if (Reflection)
{
// Reflection
if (!sphere.IsWall && /* ignore walls */
reflectionLimit > 0)
{
var reflectionMaterial = Conversions.FromColor(Colors.White);
var refVecNorm = Vector3.Normalize(rayVecNorm - 2 * Vector3.Dot(nVecNorm, rayVecNorm) * nVecNorm);
var refVec2 = refVecNorm + (Vector3.One - refVecNorm) * (float)Math.Pow((1 - Vector3.Dot(nVecNorm, refVecNorm)), 5);
var reflectionRay = new Ray(hitPointVec, refVec2);
var reflectionColor = CalcColor(reflectionRay, 0, --reflectionLimit);
var reflection = Vector3.Multiply(reflectionColor, reflectionMaterial) * 0.25f;
rgb += reflection;
}
}
for (int i = 0; i < _lightSources.Length; i++)
{
var lightSource = _lightSources[i];
var lVec = lightSource.Center - hitPointVec;
var lVecNorm = Vector3.Normalize(lVec);
var light_cos = Vector3.Dot(nVecNorm, lVecNorm);
if (light_cos >= 0)
{
var light = Conversions.FromColor(lightSource.Color);
if (Shadows)
{
if (SoftShadows)
{
light_cos *= GetShadowedRatio(hitPointVec, lightSource);
}
else
{
// Shadows
if (HasObjectInFrontOfLightSource(hitPointVec, lightSource.Center))
{
light_cos *= 0.01f;
}
}
}
if (DiffuseLambert)
{
// Diffuse "Lambert"
var diffuse = Vector3.Multiply(light, material) * light_cos;
rgb += diffuse;
}
if (SpecularPhong)
{
// Ignore walls
if (!sphere.IsWall)
{
// Specular "Phong"
var sVec = (lVec - ((Vector3.Dot(lVec, nVecNorm)) * nVecNorm));
var rVec = lVec - (2 * sVec);
var specular = light * (float)Math.Pow((Vector3.Dot(Vector3.Normalize(rVec), rayVecNorm)), SpecularPhongFactor);
rgb += specular;
}
}
}
}
}
else
{
if (pathTracingLimit > 0)
{
var numberOfRandomRays = 0;
bool isBounced = pathTracingLimit < PathTracingMaxBounces;
if (!isBounced)
{
numberOfRandomRays = PathTracingRays;
}
else
{
var russianRoulette = (float)_random.NextDouble();
if (russianRoulette > 0.2f)
{
numberOfRandomRays = 1;
}
}
if (numberOfRandomRays > 0)
{
// Source: https://www.scratchapixel.com/lessons/3d-basic-rendering/global-illumination-path-tracing/global-illumination-path-tracing-practical-implementation
Vector3 indirectDiffuse = Vector3.Zero;
Vector3 ntVec = Vector3.Zero;
if (Math.Abs(nVecNorm.X) > Math.Abs(nVecNorm.Y))
{
ntVec = (new Vector3(nVecNorm.Z, 0, -nVecNorm.X) / (float)Math.Sqrt(nVecNorm.X * nVecNorm.X + nVecNorm.Z * nVecNorm.Z));
}
else
{
ntVec = (new Vector3(0, -nVecNorm.Z, nVecNorm.Y) / (float)Math.Sqrt(nVecNorm.Y * nVecNorm.Y + nVecNorm.Z * nVecNorm.Z));
}
var nbVec = Vector3.Cross(nVecNorm, ntVec);
for (int i = 0; i < numberOfRandomRays; i++)
{
var cosTheta = (float)_random.NextDouble();
var phi = (float)(_random.NextDouble() * 2 * Math.PI);
var sinTheta = (float)Math.Sqrt(1 - cosTheta * cosTheta);
float x = sinTheta * (float)Math.Cos(phi);
float z = sinTheta * (float)Math.Sin(phi);
var sampleLocalVec = new Vector3(x, cosTheta, z);
var sampleWorldVec = new Vector3()
{
X = sampleLocalVec.X * nbVec.X + sampleLocalVec.Y * nVecNorm.X + sampleLocalVec.Z * ntVec.X,
Y = sampleLocalVec.X * nbVec.Y + sampleLocalVec.Y * nVecNorm.Y + sampleLocalVec.Z * ntVec.Y,
Z = sampleLocalVec.X * nbVec.Z + sampleLocalVec.Y * nVecNorm.Z + sampleLocalVec.Z * ntVec.Z
};
var randomRay = new Ray(hitPointVec, sampleWorldVec);
indirectDiffuse += CalcColor(randomRay, pathTracingLimit - 1, 0) * cosTheta;
}
indirectDiffuse /= numberOfRandomRays * _pdf;
rgb += Vector3.Multiply(indirectDiffuse, material) * sphere.Reflectiveness;
}
else
{
rgb += material * sphere.Brightness;
}
}
else
{
rgb += material * sphere.Brightness;
}
}
}
return(rgb);
}
public ImageSource GetImage()
{
//** clear buffers
Array.Clear(_rgbArray, 0, _rgbArray.Length);
for (int x = 0; x < _screenWidth; x++)
{
for (int y = 0; y < _screenHeight; y++)
{
_zBufferArray[x, y] = float.PositiveInfinity;
}
}
if (_useDeferredRenderer)
{
//** first pass (Z-Prepass)
for (int i = 0; i < _triangles.Length; i++)
{
var triangle = _triangles[i];
if (!triangle.IsBackfacing)
{
for (int x = (int)Math.Min(0, Math.Max(triangle.MinScreenX, 0)); x < (int)Math.Min(Math.Max(triangle.MaxScreenX, 0), _screenWidth); x++)
{
for (int y = (int)Math.Min(0, Math.Max(triangle.MinScreenY, 0)); y < (int)Math.Min(Math.Max(triangle.MaxScreenY, 0), _screenHeight); y++)
{
var z = triangle.CalcZ(x, y);
if (!float.IsInfinity(z) &&
!float.IsNaN(z) &&
z < _zBufferArray[x, y])
{
_zBufferArray[x, y] = z;
}
}
}
}
}
//** second pass
for (int i = 0; i < _triangles.Length; i++)
{
var triangle = _triangles[i];
if (!triangle.IsBackfacing)
{
for (int x = (int)Math.Min(0, Math.Max(triangle.MinScreenX, 0)); x < (int)Math.Min(Math.Max(triangle.MaxScreenX, 0), _screenWidth); x++)
{
for (int y = (int)Math.Min(0, Math.Max(triangle.MinScreenY, 0)); y < (int)Math.Min(Math.Max(triangle.MaxScreenY, 0), _screenHeight); y++)
{
float z = _zBufferArray[x, y];
if (_visualizeZBuffer)
{
var zcolor = (int)((z - ZBUFFER_VISUALIZE_MIN) / (ZBUFFER_VISUALIZE_MAX - ZBUFFER_VISUALIZE_MIN) * 255) * new Vector3(1f / 255, 1f / 255, 1f / 255);
_rgbArray[x, y] = zcolor;
}
else
{
var rgb = Vector3.Zero;
if (triangle.CalcColorDeferred(x, y, _lightSources, z, out rgb))
{
_rgbArray[x, y] = rgb;
}
}
}
}
}
}
}
else
{
for (int i = 0; i < _triangles.Length; i++)
{
var triangle = _triangles[i];
if (!triangle.IsBackfacing)
{
for (int x = (int)Math.Min(0, Math.Max(triangle.MinScreenX, 0)); x < (int)Math.Min(Math.Max(triangle.MaxScreenX, 0), _screenWidth); x++)
{
for (int y = (int)Math.Min(0, Math.Max(triangle.MinScreenY, 0)); y < (int)Math.Min(Math.Max(triangle.MaxScreenY, 0), _screenHeight); y++)
{
float z;
Vector3 rgb;
if (triangle.CalcColor(x, y, _lightSources, out z, out rgb) &&
!float.IsInfinity(z) &&
!float.IsNaN(z))
{
if (z < _zBufferArray[x, y])
{
_zBufferArray[x, y] = z;
if (_visualizeZBuffer)
{
var zcolor = (int)((z - ZBUFFER_VISUALIZE_MIN) / (ZBUFFER_VISUALIZE_MAX - ZBUFFER_VISUALIZE_MIN) * 255) * new Vector3(1f / 255, 1f / 255, 1f / 255);
_rgbArray[x, y] = zcolor;
}
else
{
_rgbArray[x, y] = rgb;
}
}
}
}
}
}
}
}
//** buffer to image
for (int x = 0; x < _screenWidth; x++)
{
for (int y = 0; y < _screenHeight; y++)
{
var rgb = _rgbArray[x, y];
var c = Conversions.FromRGB(rgb, _gammaCorrect);
_bitmap.Set(x, y, c);
}
}
return(_bitmap.GetImageSource());
}
public string GetImageFileName(int width, int height, double dpiX, double dpiY, CancellationToken cancellationToken, string settingsSummary, string exportDirectory)
{
var sw = Stopwatch.StartNew();
OutputLogEveryXPixel = (width * height / 100);
if (AccelerationStructure)
{
_accelerationStructure = BVHNode.BuildTopDown(_spheres, _logger);
}
var bitmap = new BitmapImage(width, height, dpiX, dpiY);
var divideX = width / (float)2;
var alignX = 1 - divideX;
var divideY = height / (float)2;
var alignY = 1 - divideY;
int workDone = 0;
int totalWork = width * height;
if (Parallelize)
{
var options = new ParallelOptions()
{
CancellationToken = cancellationToken, MaxDegreeOfParallelism = Environment.ProcessorCount
};
Parallel.For(0, width, options, i =>
{
for (int j = 0; j < height; j++)
{
if (cancellationToken.IsCancellationRequested)
{
break;
}
if (AntiAliasing)
{
Vector3 result = Vector3.Zero;
for (int k = 0; k < AntiAliasingSampleSize; k++)
{
var dx = (float)_random.NextGaussian(0d, 0.5d);
var dy = (float)_random.NextGaussian(0d, 0.5d);
var x = (i + alignX + dx) / divideX;
var y = ((height - j) + alignY + dy) / divideY;
var rgb = GetColor(x, y);
result += rgb;
}
var avg_rgb = result * (1f / AntiAliasingSampleSize);
var c = Conversions.FromRGB(avg_rgb, GammaCorrect);
bitmap.Set(i, j, c);
}
else
{
var x = (i + alignX) / divideX;
var y = ((height - j) + alignY) / divideY;
var rgb = GetColor(x, y);
var c = Conversions.FromRGB(rgb, GammaCorrect);
bitmap.Set(i, j, c);
}
var value = Interlocked.Increment(ref workDone);
if (value % OutputLogEveryXPixel == 0)
{
var progress = (float)value / totalWork;
WriteOutput($"{(progress * 100):F3}% progress. Running {sw.Elapsed}. Remaining {TimeSpan.FromMilliseconds(sw.Elapsed.TotalMilliseconds / progress * (1f - progress))}.");
}
}
});
}
else
{
for (int i = 0; i < width; i++)
{
if (cancellationToken.IsCancellationRequested)
{
break;
}
for (int j = 0; j < height; j++)
{
if (cancellationToken.IsCancellationRequested)
{
break;
}
if (AntiAliasing)
{
Vector3 result = Vector3.Zero;
for (int k = 0; k < AntiAliasingSampleSize; k++)
{
var x = (i + alignX + (float)_random.NextGaussian(0d, 0.5d)) / divideX;
var y = ((height - j) + alignY + (float)_random.NextGaussian(0d, 0.5d)) / divideY;
var rgb = GetColor(x, y);
result += rgb;
}
var avg_rgb = result * (1f / AntiAliasingSampleSize);
var c = Conversions.FromRGB(avg_rgb, GammaCorrect);
bitmap.Set(i, j, c);
}
else
{
// Question: Why is it mirrored?
var x = (i + alignX) / divideX;
var y = ((height - j) + alignY) / divideY;
var rgb = GetColor(x, y);
var c = Conversions.FromRGB(rgb, GammaCorrect);
bitmap.Set(i, j, c);
}
++workDone;
if (workDone % OutputLogEveryXPixel == 0)
{
var progress = (float)workDone / totalWork;
WriteOutput($"{(progress * 100):F3}% progress. Running {sw.Elapsed}. Remaining {TimeSpan.FromMilliseconds(sw.Elapsed.TotalMilliseconds / progress * (1f - progress))}.");
}
}
}
}
if (cancellationToken.IsCancellationRequested)
{
WriteOutput("Operation canceled by user.");
return(null);
}
var imageSource = bitmap.GetImageSource();
sw.Stop();
return(SaveImage(imageSource, sw.Elapsed, settingsSummary, exportDirectory));
}
