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View Full Version : Do graphic cards have standard SGI Open GL Feastures?



Wendel Dean Renner
06-09-2001, 12:31 PM
I want to port an application from SGI Unix computer to PC architecture under Linux or Windows. The question is, what card do I buy that has some of the OpenGL features that I
need:

(1) transparent surfaces need alpha blending. Do all the PC cards
have that?
(2) 3D texture mapping. Do any of the cards have that?
(3) four overlay planes. All Unix SGI computers have 4 overlay
planes. Can I get that in a PC card?
(4) All SGI computers have 12 bit pseudo color visual besides 8 bit
pseudo color and 24 plane true color. Is there any graphics card with
that? This last feature I can live without but it is nice for some things.

DaViper
06-10-2001, 10:39 PM
1. all new consumer cards have alpha blending

2. ATI radeon and GeForce3

3. hmm overlay planes, not sure what you mean, GF2 has two texture units GF3 has 4, not sure about ATI

4 don't think so max is32Bit in RGBA mode

Wendel Dean Renner
06-11-2001, 11:29 AM
Originally posted by DaViper:
1. all new consumer cards have alpha blending

2. ATI radeon and GeForce3

3. hmm overlay planes, not sure what you mean, GF2 has two texture units GF3 has 4, not sure about ATI

Overlay planes work like this. If there is a value written to a pixel in an overlay plane, other than zero, that value will be displayed. Otherwise for zero the data in the image planes are displayed. Most systems will have two overlay planes reserved for the mouse cursor and rubber banding windows. On SGI computers, there are also four overlay planes user applications can use. The planes are pseudo color with a look up table from 1 to 15. 0 pixel value does not map to an entry in the look up table, rather the image data shows. The mouse overlay plane takes precedent over the user planes which take precedent over the image planes, what ever visual that might be.

4 don't think so max is32Bit in RGBA mode

A 12 plane visual has a color look up table from 0 to 4095. At each address is stored 8 bits for each of red, green, and blue. It works just like 8 plane pseudo color, only has a longer look up table. Pseudo color is a different animal from true color where the color is stored directly into the image planes.