Re: [Plib-users] Semi-transparent plane

[Steve B. <sjb...@ai...>]

Martin Howard wrote:

> I have the Red Book, and the OpenGL Superbible and I've read the PLIB
> documentation on the web site.  From what I can tell, you need to draw
> everything else before you draw the translucent plane, but I don't know how
> to achive this with SSG (I tried adding the plane as the last child to the
> scene, but it doens't seem to work).

SSG knows that translucent things have to be drawn last...and it does it
automatically on your behalf.

>  Also, it would appear that
> ssgSimpleState cannot achieve the effects on its own: I need callbacks that
> call 'glBlendFunc()' and 'glDepthMask()'.

glBlendFunc is set to a 'sensible' value by default - you shouldn't need
to tough glDepthMask in this application.
 
> So, please, excuse a dumb beginner, but am I on the right track with
> callbacks?  How do I control drawing order?

You don't need to do that.  SSG does it for you...just sit back and enjoy
the ride!

>  And am I missing anything
> obvious?  As it is, my transluscent plane isn't being drawn at all.

Then I *suspect* you have something else wrong.  Maybe it's back-facing?
Maybe it's alpha is too low to show up?  It's hard to tell without seeing
the code.
 
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