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object graphics - transparent surfaces [message #48861]

Tue, 30 May 2006 00:20

greg michael
Messages: 163
Registered: January 2006

Senior Member

I'm trying to make some 3d red/blue anaglyphs using object graphics. I
manage to blend the red surface onto the blue using the alpha channel
and /depth_test_disable on the second surface, something like:

oSurface2 = OBJ_NEW('IDLgrSurface', data,x,y, style=2, alpha=.5, $
color=[255,255,255],texture_map=oImage2,shading=1)
oModel2 = OBJ_NEW('IDLgrModel',/depth_test_disable)
oModel2->add,oSurface2

In most cases it works fine, but occasionally I get ugly pure-red bands
on the tops of steep ridges. Looking more closely at the idlgrsurface
alpha_channel documentation, it seems to be saying this technique is
not recommended... some facets may be rendered in the wrong order for
transparency. So is there a better way?

I could render one, read it back, then the other, read it back, blend
them myself, and then display. But that wouldn't be a nice way to make
an interactive object. By the way, I'm using 6.1, just in case anyone
happens to know whether it's been changed since.

regards,
Greg

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[Message index]

		object graphics - transparent surfaces By: greg michael on Tue, 30 May 2006 00:20
		Re: object graphics - transparent surfaces By: Rick Towler on Thu, 08 June 2006 12:32
		Re: object graphics - transparent surfaces By: greg michael on Fri, 16 June 2006 02:42
		Re: object graphics - transparent surfaces By: Rick Towler on Tue, 06 June 2006 13:22
		Re: object graphics - transparent surfaces By: Rick Towler on Tue, 06 June 2006 08:49
		Re: object graphics - transparent surfaces By: Michael Galloy on Wed, 28 June 2006 08:42

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