Mandelbrot

gistfile1.m

-(void)generateImageOfSize:(CGSize)imageSize
{
	// Determine integer size of image
	NSInteger imageIntWidth = ceilf(imageSize.width);
	NSInteger imageIntHeight = ceilf(imageSize.height);

	// Determine coordinate maxima
    assert(zoomFactor > 0.0f);
    float coordMaxX = coordMinX + imageIntWidth / zoomFactor; 
    float coordMaxY = coordMinY + imageIntHeight / zoomFactor; 
    float deltaX = (coordMaxX - coordMinX) / imageIntWidth;
    float deltaY = (coordMaxY - coordMinY) / imageIntHeight;

    // Create image buffer
    NSInteger nx = imageIntWidth;
    NSInteger ny = imageIntHeight;
    UInt8 *imageBuffer = malloc(nx * ny * 3 * sizeof(UInt8));
    
    // Fill buffer using Mandelbrot calculation
    float logMaxIterations = log(MBMaxMandelbrotIterations);
    NSUInteger ix, iy;
    for ( ix = 0; ix < nx; ix++ ) {
        float cReal = coordMinX + ix * deltaX;
        for ( iy = 0; iy < ny; iy++ ) {
            float cImag = coordMinY + iy * deltaY;
        
        	// Perform Mandelbrot iterations to see if point leads to escape
            NSUInteger iterationIndex;
            float zReal = 0.0f;
            float zImag = 0.0f;
            float zRealNew;
            for( iterationIndex = 0; iterationIndex < MBMaxMandelbrotIterations && 
            	fabs(zReal) < MBEscapeDistance && fabs(zImag) < MBEscapeDistance; iterationIndex++ ) {
                zRealNew = (zReal * zReal) - (zImag * zImag) + cReal;
                zImag = (2.0 * zReal * zImag ) + cImag;
                zReal = zRealNew;
            }
            
            // Determine corresponding color and store in buffer
            float logIterations = log(iterationIndex);
            float depthRatio = logIterations / logMaxIterations;
            NSUInteger imageOffset = iy * nx * 3 + ix * 3;
            imageBuffer[imageOffset] = 255 * (1.0f - depthRatio);
            imageBuffer[imageOffset+1] = 255 * (1.0f - depthRatio);
            imageBuffer[imageOffset+2] = 255 * (1.0f - depthRatio);
        }
	}
    
    // Create image from buffer
	[self setImageForBuffer:imageBuffer pixelsX:nx pixelsY:ny];
}


-(void)setImageForBuffer:(UInt8 *)buffer pixelsX:(NSUInteger)nx pixelsY:(NSUInteger)ny
{
    CGDataProviderRef provider = CGDataProviderCreateWithData( NULL, buffer, nx*ny*3, BrotMakerReleaseImageData );
    CGImageRef newImage = CGImageCreate( nx, ny, 8, 24, nx * 3, [[NSColorSpace genericRGBColorSpace] CGColorSpace], kCGBitmapByteOrderDefault, provider, NULL, NO, kCGRenderingIntentDefault );
    CGDataProviderRelease( provider );
	self.image = newImage;    
    CGImageRelease(image);
}