PDA

View Full Version : blending with a constant rgba value on low spec 3d cards?



noeska
07-02-2004, 06:18 PM
i want to create a transparent surface with emboss bumpmapping.
for the emboss bumpmapping is use the alpha channel.
so i cannot use it anymore for controlling how transparent the surface will be.
I figured out it is possible to use the following with opengl 1.4:

glblendcolor(1,1,1,0.1); //0.0 = solid 1.0 = transparent
glBlendFunc(GL_SRC_ALPHA, GL_CONSTANT_ALPHA); //now object is not affected by alpha channel of texture

This seems to do the trick. But only on high end graphics cards as a test on a TNT graphics card gives a 0-1 fps framerate.
Using only:

glBlendFunc(GL_SRC_ALPHA,GL_ONE_MINUS_SRC_ALPHA);
Gives me back 33fps. But without the control on how transparent the surface is.
Is there a way do both on a TNT?

Clootie
08-02-2004, 11:08 AM
Create second 1x1 texture and use it with _MODULATE_ blending