Cocoa OpenGL Texture Creation - cocoa

Question

I am working on my first OpenGL application using Cocoa (I have used OpenGL ES on the iPhone) and I am having trouble loading a texture from an image file. Here is my texture loading code:
#interface MyOpenGLView : NSOpenGLView
{
GLenum texFormat[ 1 ]; // Format of texture (GL_RGB, GL_RGBA)
NSSize texSize[ 1 ]; // Width and height
GLuint textures[1]; // Storage for one texture
}
- (BOOL) loadBitmap:(NSString *)filename intoIndex:(int)texIndex
{
BOOL success = FALSE;
NSBitmapImageRep *theImage;
int bitsPPixel, bytesPRow;
unsigned char *theImageData;
NSData* imgData = [NSData dataWithContentsOfFile:filename options:NSUncachedRead error:nil];
theImage = [NSBitmapImageRep imageRepWithData:imgData];
if( theImage != nil )
{
bitsPPixel = [theImage bitsPerPixel];
bytesPRow = [theImage bytesPerRow];
if( bitsPPixel == 24 ) // No alpha channel
texFormat[texIndex] = GL_RGB;
else if( bitsPPixel == 32 ) // There is an alpha channel
texFormat[texIndex] = GL_RGBA;
texSize[texIndex].width = [theImage pixelsWide];
texSize[texIndex].height = [theImage pixelsHigh];
if( theImageData != NULL )
{
NSLog(#"Good so far...");
success = TRUE;
// Create the texture
glGenTextures(1, &textures[texIndex]);
NSLog(#"tex: %i", textures[texIndex]);
NSLog(#"%i", glIsTexture(textures[texIndex]));
glPixelStorei(GL_UNPACK_ROW_LENGTH, [theImage pixelsWide]);
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
// Typical texture generation using data from the bitmap
glBindTexture(GL_TEXTURE_2D, textures[texIndex]);
NSLog(#"%i", glIsTexture(textures[texIndex]));
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, texSize[texIndex].width, texSize[texIndex].height, 0, texFormat[texIndex], GL_UNSIGNED_BYTE, [theImage bitmapData]);
NSLog(#"%i", glIsTexture(textures[texIndex]));
}
}
return success;
}
It seems that the glGenTextures() function is not actually creating a texture because textures[0] remains 0. Also, logging glIsTexture(textures[texIndex]) always returns false.
Any suggestions?
Thanks,
Kyle

Answer 1

glGenTextures(1, &textures[texIndex] );
What is your textures definition?
glIsTexture only returns true if the texture is already ready. A name returned by glGenTextures, but not yet associated with a texture by calling glBindTexture, is not the name of a texture.
Check if the glGenTextures is by accident executed between glBegin and glEnd -- that's the only official failure reason.
Also:
Check if the texture is square and has dimensions that are a power of 2.
Although it isn't emphasized anywhere enough iPhone's OpenGL ES implementation requires them to be that way.

Answer 2

OK, I figured it out. It turns out that I was trying to load the textures before I set up my context. Once I put loading textures at the end of the initialization method, it worked fine.
Thanks for the answers.
Kyle