Is there any reason the noise has to be unique each time? Could you just
generate a noise file and composite that over whatever you want? Unless you're
doing something with cryptography, noise, is noise, is noise. It all basically
looks the same so reusing a single file seems like it could serve your
purposes...
On Jun 14, 2011, at 5:56 PM, Stephen Blinkhorn wrote:
> Hi all,
>
> I'm looking to fill a large custom view with noise. The solution I have
> arrived at so far is taking much too long to draw for it to be useable. Does
> anyone know any better ways of achieving this in Cocoa? The basic idea is to
> add an amount of noise to a base color pixel by pixel, for example:
>
> // create base color
> NSColor *base_color = [NSColor colorWithCalibratedRed:0.25 green:0.3
> blue:0.35 alpha:1.0]; //[style colorForKey:@"Section"];
>
> // get color components
> CGFloat red, green, blue, alpha;
> [base_color getRed:&red green:&green blue:&blue alpha:&alpha];
>
> // create rect and boundary variables
> NSRect noise_rect = NSMakeRect(0, 0, 1, 1);
> NSInteger width = [self bounds].size.width;
> NSInteger height = [self bounds].size.height;
>
> // main loop
> NSInteger x_pos = 0;
> for(; x_pos<width; x_pos+=1)
> {
> NSInteger y_pos = 0;
> for(; y_pos<height; y_pos+=1)
> {
> // create noise (0..1 range)
> float pixel_noise = (rand() % 1000 * 0.0001);
> // add noise to color variables
> [[NSColor colorWithCalibratedRed:red+pixel_noise
> green:green+pixel_noise blue:blue+pixel_noise alpha:alpha] set];
> // draw a 1X1 pixel rect
> noise_rect.origin.x = x_pos;
> noise_rect.origin.y = y_pos;
> NSRectFill(noise_rect);
> };
> };
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