NPOT Textures

From Unofficial TransGaming Wiki

The capability to render Non-Power of Two (NPOT) textures is avaiable as of Cedega 4.2.

Technical Background

Standard OpenGL requires all textures to have a height and width that are powers of two, meaning it cannot handle textures that have different dimensions. However, there are OpenGL extensions that permit the use of these NPOT textures.

GL_ARB_texture_non_power_of_two is an extension shown by cards that are not subject at all to the power of two texture requirements. This extension is part of the OpenGL 2.0 specification and is only offered by the most modern of modern hardware (eg. Nvidia 6800GT). If your hardware supports this extension, Cedega will not use the NPOT rendering code as it is not required.

GL_ARB_texture_rectangle is a far more common extension and is the extension that will be used to render NPOT textures in Cedega. It handles these textures using a special texture target that posesses limited capabilities compared to regular textures. Unfortunately, on older cards these textures do not play well in combination with Vertex shaders.

As a result NPOT texturing will work perfectly fine on GeForce FX/Radeon 9500 or better hardware. However, it will be disabled by default for lower cards. To enable it on these cards, you must disable vertex shaders.

Relevant Settings

Enable Vertex Shaders:
For older graphics cards, you may need to uncheck this box to allow NPOT texturing to operate.

[d3dgl] RectangleTextures:
This is a setting found in the Cedega config file, it defaults to "Auto". This setting allows you to explicitly state whether the NPOT code path is used for non-power of two textures.