[PD] GEM and transparency

bbogart at ryerson.ca bbogart at ryerson.ca
Fri Jul 18 03:33:48 CEST 2003

Hey Martin,

your problem is render-order not transparency. transparency only works in one direction, so you have to tell Gem the stacking order from back to front for things to look properly transparent.

Gemheads with smaller numbers get rendered first (0-1-2-3-4 etc..) and the same goes for separators, just specify the render order (back to front) as an argument to the sepatators.

I've attached a demo example to make things more clear


----- Original Message -----
From: Martin Dupras <martin.dupras at uwe.ac.uk>
Date: Thursday, July 17, 2003 7:30 pm
Subject: [PD] GEM and transparency

> I have a peculiar problem.
> I'm taking a video feed with pix_video then applying it as a 
> texture to
> three squares, each connected to [alpha] and [colorRGB v1 v2 v3], 
> wherethe first square is red only, the second green, and the third 
> blue.
> Now I want to superimpose the three squares so that I can 
> translate them
> independently.
> One approach that I tried was using one gemhead, the pix_video and
> textures2 objects, then using separator to feed to the three 
> squares. It
> works but if I set the transparency of any square to anything 
> other than
> 0, the black obscures the squares behind.
> I tried another approach, where I used three different chains, but 
> thenonly one of the chains can access the video feed.
> Questions:
> 1) is there a way to make transparency work such that "black" 
> pixels are
> transparent?
> 2) is there a way to make several [pix_video] objects access the same
> video feed?
> Many thanks!
> - martin
> _______________________________________________
> PD-list mailing list
> PD-list at iem.at
> http://iem.at/cgi-bin/mailman/listinfo/pd-list
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