Opengl Environment Variables; Opengl Texturing & Extensions; Efficient Use Of Multiple Textures; Considerations Specific To Asus 3Dp-V500Tx Board - Asus 3DP-V500TX User Manual

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IV. UTILITIES & DRIVERS

OpenGL Environment Variables

The 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 use

of the Fast Clear Planes by the OpenGL Installable Client Driver. This is done by

setting the variable to TRUE within the system applet of the control panels.

OpenGL Texturing & Extensions

OpenGL applications that wish to render primitives with multiple texture maps will

achieve much higher performance by avoiding the invoking of the different textures

in 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 a

display list. Switching between different textures is then achieved by referencing

the appropriate display list. Since display lists are not editable in OpenGL, the OpenGL

implementation 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 the

application 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 performance

for ASUS 3DP-V500TX.

The second option is to use the OpenGL texture object extension. This functionality

has become a standard part of the OpenGL version 1.1 functionality. Unlike the use

of textures in display lists, texture objects are fully editable and may have their

images and parameters altered at any time (when bound). Refer to Appendix E for

further details.

For the ASUS 3DP-V500TX, texture data is stored in the local buffer memory on

the graphics card. The memory available for textures is therefore constrained by the

local buffer memory available. It is also constrained by the amount of local buffer

memory already consumed for the depth buffer, stencil buffer, etc., which varies

according 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 depth

buffer, stencil buffer) is lowered.

ASUS 3DP-V500TX

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