/// <summary>
/// CDF-based sampling.
/// </summary>
/// <param name="random">[0,1] uniform random value.</param>
/// <param name="rnd">Optional random generator instance. If provided, internal randomization is possible.</param>
public virtual void GetSample(out double x, out double y, double random, RandomJames rnd = null)
{
if (cdf == null)
{
CollectCdf();
}
// CDF-based importance sampling:
int ia = 0;
int ib = cdfRes - 1;
double a = 0.0;
double b = 1.0;
do
{
int ip = (ia + ib) >> 1;
double p = cdf[ip];
if (p < random)
{
ia = ip;
a = p;
}
else
{
ib = ip;
b = p;
}
}while (ia + 1 < ib);
int ix = ia / resolution;
int iy = ia % resolution;
x = (ix + (rnd == null ? 0.5 : rnd.UniformNumber())) * pixel;
y = (iy + (rnd == null ? 0.5 : rnd.UniformNumber())) * pixel;
}
/// <summary>
/// Renders the single pixel of an image.
/// </summary>
/// <param name="x">Horizontal coordinate.</param>
/// <param name="y">Vertical coordinate.</param>
/// <param name="color">Computed pixel color.</param>
/// <param name="rnd">Shared random generator.</param>
public override void RenderPixel(int x, int y, double[] color, RandomJames rnd)
{
Debug.Assert(color != null);
Debug.Assert(rnd != null);
int bands = color.Length;
int b;
Array.Clear(color, 0, bands);
double[] tmp = new double[bands];
int i, j, ord;
double step = 1.0 / superXY;
double amplitude = Jittering * step;
double origin = 0.5 * (step - amplitude);
double x0, y0;
for (j = ord = 0, y0 = y + origin; j++ < superXY; y0 += step)
{
for (i = 0, x0 = x + origin; i++ < superXY; x0 += step)
{
ImageFunction.GetSample(x0 + amplitude * rnd.UniformNumber(),
y0 + amplitude * rnd.UniformNumber(),
ord++, Supersampling, rnd, tmp);
for (b = 0; b < bands; b++)
{
color[b] += tmp[b];
}
}
}
double mul = step / superXY;
if (Gamma > 0.001)
{ // gamma-encoding and clamping
double g = 1.0 / Gamma;
for (b = 0; b < bands; b++)
{
color[b] = Arith.Clamp(Math.Pow(color[b] * mul, g), 0.0, 1.0);
}
}
else // no gamma, no clamping (for HDRI)
{
for (b = 0; b < bands; b++)
{
color[b] *= mul;
}
}
}
/// <summary>
/// Allocate large enough colormap..
/// </summary>
public static void AssertColors(int num)
{
int i;
if (debugColors == null ||
debugColors.Count < num)
{
debugColors = new List <Color>(num);
RandomJames rnd = new RandomJames();
for (i = 0; i < num; i++)
{
int R = rnd.RandomInteger(0, 255);
int G = rnd.RandomInteger(0, 255);
int B = rnd.RandomInteger(0, 255);
if (R >= 128 && G >= 128 && B >= 128)
{
if (rnd.UniformNumber() > 0.5)
{
R -= 128;
}
else
{
G -= 128;
}
}
debugColors.Add(Color.FromArgb(R, G, B));
}
}
}
/// <summary>
/// CDF-based sampling.
/// </summary>
/// <param name="x">Output horizontal coordinate from the [0.0,width) range.</param>
/// <param name="y">Output vertical coordinate from the [0.0,height) range.</param>
/// <param name="random">[0,1] uniform random value.</param>
/// <param name="rnd">Optional random generator instance. If provided, internal randomization is possible.</param>
public void GetSample(out double x, out double y, double random, RandomJames rnd = null)
{
if (cdf == null)
{
PrepareCdf();
}
// CDF-based importance sampling:
int ia = 0;
int ib = width * height;
double a = 0.0;
double b = 1.0;
do
{
int ip = (ia + ib) >> 1;
double p = cdf[ip];
if (p < random)
{
ia = ip;
a = p;
}
else
{
ib = ip;
b = p;
}
}while (ia + 1 < ib);
y = ia / width;
x = ia % width;
if (rnd != null)
{
x += rnd.UniformNumber();
y += rnd.UniformNumber();
}
else
{
x += 0.5;
y += 0.5;
}
}
public void generateSample(int r, int t)
{
if (t > 1)
{
if (r == rank &&
t == total)
{
return;
}
int uCell, vCell;
if (t != total || r < rank) // [re-]initialization
{
total = t;
uCell = rnd.PermutationFirst(total, ref permU);
vCell = rnd.PermutationFirst(total, ref permV);
}
else
{
uCell = Math.Max(rnd.PermutationNext(ref permU), 0);
vCell = Math.Max(rnd.PermutationNext(ref permV), 0);
}
rank = r;
// point sample will be placed into [ uCell, vCell ] cell:
u = (uCell + rnd.UniformNumber()) / total;
v = (vCell + rnd.UniformNumber()) / total;
}
else
{
u = rnd.UniformNumber();
v = rnd.UniformNumber();
}
// TODO: do something like:
sample = source.position + u * source.width + v * source.height;
}
int ActivateParticles(int nMax)
{
int nCount = Math.Min(nMax, particles.Count - activeParticles);
if (nCount < 1)
{
return(0);
}
TotalSpawned += nCount;
int nCountToDo = nCount;
double fJitterRange = 0.1 / nCountToDo;
foreach (var par in particles)
{
if (nCountToDo <= 0)
{
break;
}
else
if (!par.active)
{
par.active = true;
par.x = xMin + 0.0001;
//par.y = yMin + 0.1 * rnd.UniformNumber() + 0.45;
par.y = 0.45 + fJitterRange * (rnd.UniformNumber() + nCountToDo - 1.0);
par.fx = 0.0;
par.fy = 0.0;
par.m = ParticleMass;
par.vx = 0.0;
par.vy = 0.0;
nCountToDo--;
}
}
activeParticles += nCount;
return(nCount);
}
/// <summary>
/// Converts the given image into B/W (1bpp) output suitable for high-resolution printer.
/// </summary>
/// <param name="input">Input image.</param>
/// <param name="output">Output (1bpp) image.</param>
/// <param name="oWidth">Default output image width in pixels.</param>
/// <param name="oHeight">Default output image height in pixels.</param>
/// <param name="param">Set of optional text parameters.</param>
/// <returns>Number of dots printed.</returns>
public static long TransformImage(Bitmap input, out Bitmap output, int oWidth, int oHeight, string param)
{
// !!!{{ TODO: write your own image dithering code here
int iWidth = input.Width;
int iHeight = input.Height;
long dots = 0L;
// custom parameters from the text-field:
double randomness = 0.0;
double dot = 0.0;
double gamma = 0.0;
bool sampling = false;
Dictionary <string, string> p = Util.ParseKeyValueList(param);
if (p.Count > 0)
{
double scale = 0.0;
// scale=<float-number>
if (Util.TryParse(p, "scale", ref scale) &&
scale > 0.01)
{
oWidth = (int)(iWidth * scale);
oHeight = (int)(iHeight * scale);
}
// rnd=<float-number>
if (Util.TryParse(p, "rnd", ref randomness))
{
randomness = Arith.Clamp(randomness, 0.0, 1.0);
}
// dot=<float-number>
if (Util.TryParse(p, "dot", ref dot))
{
dot = Math.Max(dot, 0.0);
}
// gamma=<float-number>
if (Util.TryParse(p, "gamma", ref gamma))
{
gamma = Math.Max(gamma, 0.0);
}
// sampling=<bool>
Util.TryParse(p, "sampling", ref sampling);
}
// create output 1bpp Bitmap
output = new Bitmap(oWidth, oHeight, PixelFormat.Format1bppIndexed);
float dx = (iWidth - 1.0f) / (oWidth - 1.0f);
float dy = (iHeight - 1.0f) / (oHeight - 1.0f);
// set the B/W palette (0 .. black, 1 .. white):
ColorPalette pal = output.Palette;
pal.Entries[0] = Color.Black;
pal.Entries[1] = Color.White;
output.Palette = pal;
int x, y;
float fx, fy;
RandomJames rnd = new RandomJames();
// convert pixel data (fast memory-mapped code):
PixelFormat iFormat = input.PixelFormat;
if (!PixelFormat.Format24bppRgb.Equals(iFormat) &&
!PixelFormat.Format32bppArgb.Equals(iFormat) &&
!PixelFormat.Format32bppPArgb.Equals(iFormat) &&
!PixelFormat.Format32bppRgb.Equals(iFormat))
{
iFormat = PixelFormat.Format24bppRgb;
}
BitmapData dataOut = output.LockBits(new Rectangle(0, 0, oWidth, oHeight), ImageLockMode.WriteOnly, output.PixelFormat);
unsafe
{
byte *optr;
// A. placing reasonable number of random dots on the paper
if (sampling)
{
dot = Math.Max(dot, 1.0);
// clear output image:
optr = (byte *)dataOut.Scan0;
for (x = 0; x++ < oHeight * dataOut.Stride;)
{
*optr++ = 255;
}
// create grayscale image able to sample points from itself:
FloatImage fi = new FloatImage(input);
fi = fi.GrayImage(true, gamma);
fi.PrepareCdf();
// sample 'dots' random dots:
dots = (long)(1.2 * oWidth * oHeight / (dot * dot));
double xx, yy;
for (long i = 0; i++ < dots;)
{
fi.GetSample(out xx, out yy, rnd.UniformNumber(), rnd);
xx = oWidth * (xx / iWidth);
yy = oHeight * (yy / iHeight);
Dot1bpp((int)xx, (int)yy, dot, dataOut);
}
}
else
{
BitmapData dataIn = input.LockBits(new Rectangle(0, 0, iWidth, iHeight), ImageLockMode.ReadOnly, iFormat);
// B. random screen using dots bigger than 1px
if (dot > 0.0)
{
// clear output image:
optr = (byte *)dataOut.Scan0;
for (x = 0; x++ < oHeight * dataOut.Stride;)
{
*optr++ = 255;
}
int dI = Image.GetPixelFormatSize(iFormat) / 8;
for (y = 0, fy = 0.0f; y < oHeight; y++, fy += dy)
{
if (!Form1.cont)
{
break;
}
for (x = 0, fx = 0.0f; x < oWidth; x++, fx += dx)
{
float gray = GetGray(fx, fy, dataIn, dI);
if (gamma > 0.0)
{
gray = (float)Math.Pow(gray, gamma);
}
float threshold = (float)(0.5 - randomness * (rnd.UniformNumber() - 0.5));
if (gray < threshold)
{
dots++;
Dot1bpp(x, y, dot, dataOut);
}
}
}
}
else
// C. random screen using individual pixels
{
int buffer;
int dI = Image.GetPixelFormatSize(iFormat) / 8;
for (y = 0, fy = 0.0f; y < oHeight; y++, fy += dy)
{
if (!Form1.cont)
{
break;
}
optr = (byte *)dataOut.Scan0 + y * dataOut.Stride;
buffer = 0;
for (x = 0, fx = 0.0f; x < oWidth; fx += dx)
{
float gray = GetGray(fx, fy, dataIn, dI);
if (gamma > 0.0)
{
gray = (float)Math.Pow(gray, gamma);
}
float threshold = (float)(0.5 - randomness * (rnd.UniformNumber() - 0.5));
buffer += buffer;
if (gray >= threshold)
{
buffer++;
}
else
{
dots++;
}
if ((++x & 7) == 0)
{
*optr++ = (byte)buffer;
buffer = 0;
}
}
// finish the last byte of the scanline:
if ((x & 7) != 0)
{
while ((x++ & 7) != 0)
{
buffer += buffer;
}
*optr = (byte)buffer;
}
}
}
input.UnlockBits(dataIn);
}
output.UnlockBits(dataOut);
}
return(dots);
// !!!}}
}
