CODEWITHSUNDEEP
iosopengl-es
M-V
M-V

Reputation: 5227

Non power of two textures in iOS

In my iOS app (targeted for iPad), I'd like to use non power of two (NPT) textures. My GL_VERSION query returns "OpenGL ES 2.0 APPLE". According to the spec, it should support NPT textures, but a simple test shows that I need to resize the texture to 2^N before it shows up.

Does Apple not support the full ES 2.0 spec? Where can I find documentation on what is not supported?

I am using Xcode 4.3.2 and iOS 5.1.

Edit:

A closer look at the ES 2.0.25 spec (section 3.8.2), reveals that there are a few conditions to be met for NPOT to work. Essentially if I use the settings below, I am able to load NPOT textures:

// use linear filetring
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR); 
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);
// clamp to edge
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

Should I close this or answer my own question?

Upvotes: 32

Views: 9465

Answers (2)

jeff
jeff

Reputation: 172

- (BOOL)isSupportNPOT {
//    GL_OES_texture_npot
//    GL_APPLE_texture_2D_limited_npot
//    GL_ARB_texture_non_power_of_two
    EAGLContext *context_ = [[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES1];
    [EAGLContext setCurrentContext:context_];
    NSArray *extensionNames = nil;
    NSString *extensionsString = [NSString stringWithCString:(const char *)glGetString(GL_EXTENSIONS) encoding:NSASCIIStringEncoding];
    extensionNames = [extensionsString componentsSeparatedByString:@" "];
    BOOL isSupport = [extensionNames containsObject:@"GL_APPLE_texture_2D_limited_npot"];
    [EAGLContext setCurrentContext:nil];
    NSLog(@"Apple Opengl support NPOT is %@", isSupport ? @"YES" : @"NO");
    return isSupport;
}

Upvotes: 0

M-V
M-V

Reputation: 5227

As mentioned in my edit, I found the solution. NPOT on ES 2.0 requires that you use linear filtering and clamp to edge. Also, no mipmaps.

Upvotes: 27

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