OpenGL ES 2.0 texture not showing on some device

Question

I found a 3D graphics framework for Android called Rajawali and I am learning how to use it. I followed the most basic tutorial which is rendering a shpere object with a 102

Answer 1

Good morning, this a typical example of non-power of 2 textures.

Textures need to be power of 2 in their resolution for a multitude of reasons, this is a very common mistake and it did happen to everybody to fall in this pitfall :) too me too.

The fact that non power of 2 textures work smoothly on some devices/GPU, depends merely to the OpenGL drivers implementation, some GPUs support them clearly, some others don't, I strongly suggest you to go for pow2 textures in order to be able to guarantee the functioning on all the devices.

Last but not least, using non power of 2 textures can lead you to a cathastrophic scenarious in GPU memory utilization since, most of the drivers which accept non-powerof2 textures, need to rescale in memory the textures to the nearest higher power of 2 factor. For instance, having a texture of 520X520 could lead to an actual memory mapping of 1024X1024.

This is something you don't want because in real world "size matters", especially on mobile devices.

You can find a quite good explanation in the OpenGL Gold Book, the OpenGL ES 2.0:

In OpenGL ES 2.0, textures can have non-power-of-two (npot) dimensions. In other words, the width and height do not need to be a power of two. However, OpenGL ES 2.0 does have a restriction on the wrap modes that can be used if the texture dimensions are not power of two. That is, for npot textures, the wrap mode can only be GL_CLAMP_TO_EDGE and the minifica- tion filter can only be GL_NEAREST or GL_LINEAR (in other words, not mip- mapped). The extension GL_OES_texture_npot relaxes these restrictions and allows wrap modes of GL_REPEAT and GL_MIRRORED_REPEAT and also allows npot textures to be mipmapped with the full set of minification filters.

I suggest you to evaluate this book since it does a quite decent coverage to this topic.