Asus 3DP-V500TX User Manual

12 ASUS 3DP-V500TXIV. UTILITIES & DRIVERSOpenGL Environment VariablesThe control panel applet is the preferred method for controlling OpenGL behavior.However, two environmental variables are described below which provide an alter-native means of changing two of the options.The environment variable GLINT_DONT_USE_FCP can be used to disable the useof the Fast Clear Planes by the OpenGL Installable Client Driver. This is done bysetting the variable to TRUE within the system applet of the control panels.OpenGL Texturing & ExtensionsEfficient use of multiple texturesOpenGL applications that wish to render primitives with multiple texture maps willachieve much higher performance by avoiding the invoking of the different texturesin immediate mode. There are two alternative options for efficient switching be-tween multiple textures.The first option is to define each texture (or array of mip map resolutions) within adisplay list. Switching between different textures is then achieved by referencingthe appropriate display list. Since display lists are not editable in OpenGL, the OpenGLimplementation is able to cache texture data defined within a display list. This cach-ing cannot be performed when a texture is invoked in immediate mode since theapplication in this case is at liberty to have changed the texture data since any previ-ous reference. The performance gain using this approach will benefit performancefor ASUS 3DP-V500TX.The second option is to use the OpenGL texture object extension. This functionalityhas become a standard part of the OpenGL version 1.1 functionality. Unlike the useof textures in display lists, texture objects are fully editable and may have theirimages and parameters altered at any time (when bound). Refer to Appendix E forfurther details.Considerations specific to ASUS 3DP-V500TX BoardFor the ASUS 3DP-V500TX, texture data is stored in the local buffer memory onthe graphics card. The memory available for textures is therefore constrained by thelocal buffer memory available. It is also constrained by the amount of local buffermemory already consumed for the depth buffer, stencil buffer, etc., which variesaccording to the current display resolution in use. I.e. there is more memory avail-able for textures when the display resolution (and therefore the size of the depthbuffer, stencil buffer) is lowered.IV. UTILITIESOpen GL