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Revision: 47317
at June 5, 2011 05:33 by shalomfriss
Initial Code 
//1) Load the image:
UIImage *collisionImage = [UIImage imageNamed:@"levelmask.png"];

//2) Get the image size:
int width = (int)collisionImage.size.width;
int height = (int)collisionImage.size.height;

//3) Allocate our array for quick lookups and clear it:
unsigned char *collisionMap = (unsigned char *)malloc( width *
height );
memset( collisionMap, 0, width * height );

//4) Get access to the raw bits of the image
CFDataRef imageData = CGDataProviderCopyData( CGImageGetDataProvider
( collisionImage.CGImage ) );
const UInt32 *pixels = (const UInt32*)CFDataGetBytePtr( imageData );

//5) Build our collision map:
for( j = 0; j < (width * height); j++ )
   if ( pixels[j] & 0xff000000 ) collisionMap[j] |= 1;

//6) Release what we no longer need:
CFRelease( imageData );

//Now, whenever you need to see if you hit something, you call a routine
//that does:
-(int)collisionForPoint:(CGPoint)point
{
        int x = (int)point.x;
        int y = (int)point.y;

        // TODO: check for boundaries here

        return collisionMap[(y*width)+x];

}
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                                        Initial Description
                                        

                                    

                                    

                                

                                                            

                                    

                                        

                                        Initial Title
                                        

                                    

                                    
Pixel perfect collision detection

                                

                                                            

                                    

                                        

                                        Initial Tags
                                        

                                    

                                    
iphone

                                

                                                            

                                    

                                        

                                        Initial Language
                                        

                                    

                                    
iPhone