Real simple transparency

Sorry, I should have gone through the forum first
There is already a post about this topic with the answers.

Well, what you need is masking. And Nehe have a tuturial about it. It uses two textures and then perform masking (i think)

But there''s another way to do it, but you will need another color channel: alpha

So, everthing that will be displayed, in alpha channel must be alpha > 0.

The rest is invisible, so alpha = 0

then in the glBendFunc you only pass the fragments with alpha > 0

cya


PROgrammer

Err... that''s interesting, can you explain it in more detail, alpha channel stuff?

Shouldn''t you just be able to do a quick and dirty one by enabling Blending?

glBlendFunc(GL_SRC_ALPHA,GL_ONE);
glEnable(GL_BLEND);

I''m just learning too, but when I do this, the darker the area is, the more transparent it is.

I''ve read nehe''s tutorial and it seems to me there is only solution for my problem which is adding an alpha channel to the texture. I still have to do that.

But it seems like nehe''s tutorial #20 can only handle overlays, since OpenGL draws first the overlay and then the other stuff on pieces that are still blank. But as I don''t need a realy overlay, but more an object which has to rotate and moves behind other scenes this is no option for me.

And Xersist, blending will cause the black part to dissapear, but the image will be blended too, so that''s also no option for me.

I will try the alpha channel option asap.

Thanks for the reactions.