POV-Ray : Newsgroups : povray.general : Odd blob / cutaway_textures behaviour Server Time
4 Aug 2024 14:25:59 EDT (-0400)
  Odd blob / cutaway_textures behaviour (Message 1 to 3 of 3)  
From: IMBJR
Subject: Odd blob / cutaway_textures behaviour
Date: 13 May 2003 17:26:42
Message: <nrm2cvoheekqmp3gper1tj52g70hfdqic4@4ax.com>
Why does:

difference {
	blob {
		threshold 0.5
		sphere {
			<-5,5,0>, 12, 1
			pigment {color rgb <1,0,0>}
		}
		sphere {
			<5,-5,0>, 12, 0.75
			pigment {color rgb <0,0,1>} 	
		}
			
	}
	box {
		<-100,100,0>,
		<100,-100,-100>
	}
	cutaway_textures 
}

come out black? Note: The help (section 6.7.10) suggests the box
should have no texture.

I can get a blue sliced blob if I do the following:

difference {
	blob {
		threshold 0.5
		sphere {
			<-5,5,0>, 12, 1
		}
		sphere {
			<5,-5,0>, 12, 0.75
		}
		pigment {color rgb <0,0,1>} 		
	}
	box {
		<-100,100,0>,
		<100,-100,-100>
	}
	cutaway_textures 
}

but this ain't what I want.

Note: Whilst going through the various permutations with this I came
across this one:

difference {
	blob {
		threshold 0.5
		sphere {
			<-5,5,0>, 12, 1
			pigment {color rgb <1,0,0>} 		
		}
		sphere {
			<5,-5,0>, 12, 0.75
			pigment {color rgb <0,0,1>} 		
		}
		
	}
	box {
		<-100,100,0>,
		<100,-100,-100>
		pigment {color rgb <0,1,0>}
	}
	cutaway_textures
	translate <-5,0,0> 
}

Which will make POV balk and stop with:
	Rendering Error: No textures in multi-texture CSG object.
	Returned from renderer with error status


------------------------
http://www.imbjr.com
http://www.subgenius.com


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From: Hughes, B 
Subject: Re: Odd blob / cutaway_textures behaviour
Date: 15 May 2003 00:40:53
Message: <3ec31a55$1@news.povray.org>
I didn't know what had become of this but it was brought up long ago I'm
sure. Now, in looking for any past discussions about it, I found the
following message post.

http://news.povray.org/povray.beta-test/24903/

And judging by that it's like there's more to cutaway_textures than you
might first think.

The blob primitive had already been an obvious difficulty due to the way it
accepts textures but this other "problem" is actually CSG-related instead.
Since cutaway_textures is only intended for difference and intersection and
not union or merge, it does seem to work as intended. Just that any other
textures added in a union overwrites it, which would certainly seem wrong
according to the usual texture hierarchy scheme IMHO.


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From: IMBJR
Subject: Re: Odd blob / cutaway_textures behaviour
Date: 15 May 2003 14:58:18
Message: <jpo7cv4o1b93155pj01e3mqfov0cn7go1u@4ax.com>
On Wed, 14 May 2003 23:40:51 -0500, "Hughes, B."
<omn### [at] charternet> wrote:

>I didn't know what had become of this but it was brought up long ago I'm
>sure. Now, in looking for any past discussions about it, I found the
>following message post.
>
>http://news.povray.org/povray.beta-test/24903/
>
>And judging by that it's like there's more to cutaway_textures than you
>might first think.
>
>The blob primitive had already been an obvious difficulty due to the way it
>accepts textures but this other "problem" is actually CSG-related instead.
>Since cutaway_textures is only intended for difference and intersection and
>not union or merge, it does seem to work as intended. Just that any other
>textures added in a union overwrites it, which would certainly seem wrong
>according to the usual texture hierarchy scheme IMHO.
>
Cheers for the info - looks like I'm gonna have to rethink my plans.

------------------------
http://www.imbjr.com
http://www.subgenius.com


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