Hi,
I trying to render a gray scale image (contains 2 channels luminosity
and alpha) using opengl. Actually this image is a png image. I am
decoding it using nsbitmaprep. But only garbage gets rendered. Can any
body tell whats wrong with following code. Or their is bug in
nsbitmapImagerep for rendering grayscale?
-(id) initPremultipliedATextureWithBitmap:(NSBitmapImageRep*)bitmap
pixelsWide:(NSUInteger)POTWide pixelsHigh:(NSUInteger)POTHigh
{
short bytesPerPixel = [bitmap bitsPerPixel]>>3;//2
unsigned char * data = calloc(1, POTHigh * POTWide * 4);
const unsigned char * originaldata = [bitmap bitmapData];
NSSize size=NSMakeSize([bitmap pixelsWide],[bitmap
pixelsHigh]); //64*64
NSUInteger bytesPerRow = [bitmap bytesPerRow];//128
NSUInteger pixelPerRow = bytesPerRow / bytesPerPixel;//64
CCTexture2DPixelFormat pixelFormat;
NSUInteger inputPixelPerRow = POTWide * 4;
int spp = [bitmap samplesPerPixel]; //2
#define FLIPPED_BITMAP 0
int i;
for (i = 0; i < size.height ; i++)
{
#if FLIPPED_BITMAP
int vrow=(int)size.height -i-1;
#else
int vrow=i;
#endif
if(spp == 2)
{
unsigned char * dest = data + (vrow * POTWide * 4);
const unsigned char * src = originaldata + (i * bytesPerRow);
int k=0;
for(k=0; k<size.width ; k++)
{
*(dest +k*4+3)=*(src+k*2+1); //alpha
*(dest +k*4) = *(src+k*2+2);//r
*(dest +k*4 + 1) = *(src+k*2);//g
*(dest +k*4 + 2) = *(src+k*2);//b
}
}
else
memcpy(data + (vrow * POTWide * 4), originaldata + (i *
bytesPerRow), bytesPerRow);
}
self = [self initWithData:data pixelFormat:pixelFormat
pixelsWide:POTWide pixelsHigh:POTHigh contentSize:size
unpackRowLength:POTWide];
return self;
};
Thanks in advance.
-indieAN
https://github.com/ANindie/cocos2d-GNUstep
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