32 pixel gap at top of opengl es texture

Answer 1

That 32 pixels are the missing ones to 512: 512 - 480 = 32. The reason is you can use only texture sizes that are powers of two with GL_TEXTURE_2D. So you have to round up your width and height to 512. You can still display only the part of the texture you want by using texture coordinates or by setting a texture matrix.

Answer 2

The iPhone 3GS supports non power-of-two textures under certain conditions. All the following must be true:

• GL_TEXTURE_WRAP_S should be set to GL_CLAMP_TO_EDGE
• GL_TEXTURE_WRAP_T should be set to GL_CLAMP_TO_EDGE
• Mipmapping must be turned off; minify with GL_LINEAR rather than GL_LINEAR_MIPMAP_LINEAR