Re: pfProject Texture and transparent textures

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From: Marcin Romaszewicz (marcin++at++asmodean.engr.sgi.com)
Date: 05/24/2000 13:22:18

Hi Devrim,

Which version of performer are you using? We did a major rewrite of the
projective texture code in 2.2.5 to solve exactly this problem. There are
sevral flags that you can pass to pfChannel::setTravMode which can be used

to fine-tune the multipass behavior:
#define PFMPASS_EMISSIVE_PASS 0x2

This must be enabled if you have emissive geometry, which requires an
extra pass.

#define PFMPASS_NONTEX_SCENE 0x4

This flag lets us skip a pass in the case of a non-textured scene.

#define PFMPASS_NO_TEXTURE_ALPHA 0x8

If there is no texture based transparency, we can skip another pass. For
your trees, you want this flag off.

#define PFMPASS_FORCE_MULTISAMPLE 0x10

Multisampling greatly simplifies the multipass algorithm. In cases where
there is no translucency, only full transparency or full opacity, the
multisample version of the algorithm will work faster even on machines
without multisampling hardware. This flag forces the multisample
transparency mode.

#define PFMPASS_BLACK_PASS 0x20

If you see opaque objects in your scene appear translucent, turn on this
flag, it will fix the problem at the cost of an extra pass.

-- Marcin

On Wed, 24 May 2000, devrim wrote:

> Hi,
>
> I have been using performer projected textures within my application (
> based on the sample in the man page ) . We also have transparent
> textured billboards which are used for lens flare and static shadows. At
> some point project texture is enabled and then at some point again it is
> disabled. I have noticed that when I use projected textures transparent
> textures look as if alpha bits are set to 1. When I don't enable
> projected textures, it is just fine, we have nice transparency. It looks
> like the color bit count has also decreased.
>
> Any ideas ?
>
> /*===============================================
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> Simulation Software Development
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