Re: Monochrome Output using pfColortable

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Nicolas Gauvin (nicolas++at++cae.ca)
Thu, 4 Dec 1997 17:13:47 -0500

On Dec 4, 2:26pm, Neil Williams wrote:
> Subject: Monochrome Output using pfColortable
> Hello again,
>
> Current problem:
> How do you convert a colour scene to black and white using pfColortable? The
> manual has just a few words on this, which I have tried, but with rather
> strange results.
>
> My scene is made up of 'manually' drawn terrain geometry and several flt
> databases. So far I've had
> some of the flt models going grey, some partially grey with original colours
> and textured detail bits still on, and some apparently not affected at all.
The
> textured terrain seems to darken, but still has colour in it.
>
> Any ideas or examples?

One way of making your scene all black and white without having to change
your geometry is to glCopyPixels your whole channel in a post draw callback
using a black and white color table that you set with the glColorTableSGI
extension.

Of course this involves the big cost of a glCopyPixels and that you are willing
to pay that price in your rendering time (can be quite a few ms depending on
your resolution and graphic card). The advantage is that everything will be
turned to black and white (textures, models, earth sky, etc...) depending on
their intensity since every drawn pixels is going through that lookup table.
Also since you are using the pixel transfer pipeline you can add other cool
effects such as gains and offsets.

If you plan to use pfColorTables you first need to convert all your regular
geosets into indexed geosets and I believe pfuHashGSetVerts can do part of that
for you.

-- 
Nicolas Gauvin              CAE Electronics Ltd., 8585 Cote De Liesse
3D Graphics Software        Saint-Laurent, Quebec, Canada, H4L-4X4
nicolas++at++cae.ca              Tel: (514) 341-2000 x2275, Fax: (514) 340-5496 
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