Hi, I am pretty new to scripting, I am trying to convert a perspective or linear image (bitmap, PIC or TIF) into a fisheye or apply a barrel effect/hemisphere. I found a C code but don't seem to make it work in GH, I need help converting it into a readable C or VB version... thanks in advance for any help...new code or fix this one :)

code is as follows:

m = new Bitmap("lillestromfisheye.jpg");
int l = bm.Width / 2;
Bitmap bmDestination = new Bitmap(4 * l, l);
Bitmap bmBilinear = new Bitmap(4 * l, l);
int i, j;
int x, y;
double radius, theta;

// for use in neighbouring indices in Cartesian coordinates
int iFloorX, iCeilingX, iFloorY, iCeilingY;
// calculated indices in Cartesian coordinates with trailing decimals
double fTrueX, fTrueY;
// for interpolation
double fDeltaX, fDeltaY;
// pixel colours
Color clrTopLeft, clrTopRight, clrBottomLeft, clrBottomRight;
// interpolated "top" pixels
double fTopRed, fTopGreen, fTopBlue;
// interpolated "bottom" pixels
double fBottomRed, fBottomGreen, fBottomBlue;
// final interpolated colour components
int iRed, iGreen, iBlue;

for (i = 0; i < bmDestination.Height; ++i)
{
for (j = 0; j < bmDestination.Width; ++j)
{
radius = (double) (l - i);
// theta = 2.0 * Math.PI * (double)(4.0 * l - j) / (double)(4.0 * l);
theta = 2.0 * Math.PI * (double) (-j) / (double) (4.0 * l);

fTrueX = radius * Math.Cos(theta);
fTrueY = radius * Math.Sin(theta);

// "normal" mode
x = (int) (Math.Round(fTrueX)) + l;
y = l - (int) (Math.Round(fTrueY));
// check bounds
if (x >= 0 && x < (2 * l) && y >= 0 && y < (2 * l))
{
bmDestination.SetPixel(j, i, bm.GetPixel(x, y));
}

// bilinear mode
fTrueX = fTrueX + (double) l;
fTrueY = (double) l - fTrueY;

iFloorX = (int) (Math.Floor(fTrueX));
iFloorY = (int) (Math.Floor(fTrueY));
iCeilingX = (int) (Math.Ceiling(fTrueX));
iCeilingY = (int) (Math.Ceiling(fTrueY));

// check bounds
if (iFloorX < 0 || iCeilingX < 0 ||
iFloorX >= (2 * l) || iCeilingX >= (2 * l) ||
iFloorY < 0 || iCeilingY < 0 ||
iFloorY >= (2 * l) || iCeilingY >= (2 * l)) continue;

fDeltaX = fTrueX - (double) iFloorX;
fDeltaY = fTrueY - (double) iFloorY;

clrTopLeft = bm.GetPixel(iFloorX, iFloorY);
clrTopRight = bm.GetPixel(iCeilingX, iFloorY);
clrBottomLeft = bm.GetPixel(iFloorX, iCeilingY);
clrBottomRight = bm.GetPixel(iCeilingX, iCeilingY);

// linearly interpolate horizontally between top neighbours
fTopRed = (1 - fDeltaX) * clrTopLeft.R + fDeltaX * clrTopRight.R;
fTopGreen = (1 - fDeltaX) * clrTopLeft.G + fDeltaX * clrTopRight.G;
fTopBlue = (1 - fDeltaX) * clrTopLeft.B + fDeltaX * clrTopRight.B;

// linearly interpolate horizontally between bottom neighbours
fBottomRed = (1 - fDeltaX) * clrBottomLeft.R + fDeltaX * clrBottomRight.R;
fBottomGreen = (1 - fDeltaX) * clrBottomLeft.G + fDeltaX * clrBottomRight.G;
fBottomBlue = (1 - fDeltaX) * clrBottomLeft.B + fDeltaX * clrBottomRight.B;

// linearly interpolate vertically between top and bottom interpolated results
iRed = (int) (Math.Round((1 - fDeltaY) * fTopRed + fDeltaY * fBottomRed));
iGreen = (int) (Math.Round((1 - fDeltaY) * fTopGreen + fDeltaY * fBottomGreen));
iBlue = (int) (Math.Round((1 - fDeltaY) * fTopBlue + fDeltaY * fBottomBlue));

// make sure colour values are valid
if (iRed < 0) iRed = 0;
if (iRed > 255) iRed = 255;
if (iGreen < 0) iGreen = 0;
if (iGreen > 255) iGreen = 255;
if (iBlue < 0) iBlue = 0;
if (iBlue > 255) iBlue = 255;

bmBilinear.SetPixel(j, i, Color.FromArgb(iRed, iGreen, iBlue));
}
}

bmDestination.Save("fisheyelandscape.jpg", System.Drawing.Imaging.ImageFormat.Jpeg);
bmBilinear.Save("fisheyebilinearlandscape.jpg", System.Drawing.Imaging.ImageFormat.Jpeg);