I am getting a render time error "too many nested textures".  Can anyone 
explain what is happening?  How many are too many, and what does POV 
consider to be a nested texture?  Afaik, I am not using syntax such as :

texture {
	texture {
		texture {
			transparent
			....
		}
	}
}

What I am doing is:

union {
	mesh {
		texture {
			transparent
		}
	}
	mesh {
		texture {
			transparent
		}
	}
	... many many of these
}

But it seems odd that it happens at render time.
Thanks.
-Jim

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In article <4040c3be$1@news.povray.org>,
 Jim Charter <jrc### [at] msncom> wrote:

> I am getting a render time error "too many nested textures".  Can anyone 
> explain what is happening?  How many are too many, and what does POV 
> consider to be a nested texture?  Afaik, I am not using syntax such as :

It appears to be something to do with warping normals, something that 
was added after 3.1. My first guess is that earlier versions didn't warp 
normals when the texture was warped...this code was written to fix it, 
but the programmer was lazy and it can only handle 100 textures at once. 
It refers to nested texture evaluations, not nested textures...I'm 
guessing you'll hit it if you have a chain of more than 100 evaluations 
of transparent patterned textures along a ray.

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: <chr### [at] tagpovrayorg>
http://tag.povray.org/

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Christopher James Huff wrote:
> In article <4040c3be$1@news.povray.org>,
>  Jim Charter <jrc### [at] msncom> wrote:
> 
> 
>>I am getting a render time error "too many nested textures".  Can anyone 
>>explain what is happening?  How many are too many, and what does POV 
>>consider to be a nested texture?  Afaik, I am not using syntax such as :
> 
> 
> It appears to be something to do with warping normals, something that 
> was added after 3.1. My first guess is that earlier versions didn't warp 
> normals when the texture was warped...this code was written to fix it, 
> but the programmer was lazy and it can only handle 100 textures at once. 
> It refers to nested texture evaluations, not nested textures...I'm 
> guessing you'll hit it if you have a chain of more than 100 evaluations 
> of transparent patterned textures along a ray.
> 
Thankyou Christopher.  That makes sense. I think.  By normals you are 
refering to the normals of the triangles in the mesh.

If I have:

mesh {
	triangle {}
	triangle {}
	triangle {}
	triangle {}
	texture a
}

Is that one evaluation, or up to four?

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Jim Charter wrote:

> Christopher James Huff wrote:
> 
>> In article <4040c3be$1@news.povray.org>,
>>  Jim Charter <jrc### [at] msncom> wrote:
>>
>>
>>> I am getting a render time error "too many nested textures".  Can 
>>> anyone explain what is happening?  How many are too many, and what 
>>> does POV consider to be a nested texture?  Afaik, I am not using 
>>> syntax such as :
>>
>>
>>
>> It appears to be something to do with warping normals, something that 
>> was added after 3.1. My first guess is that earlier versions didn't 
>> warp normals when the texture was warped...this code was written to 
>> fix it, but the programmer was lazy and it can only handle 100 
>> textures at once. It refers to nested texture evaluations, not nested 
>> textures...I'm guessing you'll hit it if you have a chain of more than 
>> 100 evaluations of transparent patterned textures along a ray.
>>
> Thankyou Christopher.  That makes sense. I think.  By normals you are 
> refering to the normals of the triangles in the mesh.
> 
> If I have:
> 
> mesh {
>     triangle {}
>     triangle {}
>     triangle {}
>     triangle {}
>     texture a
> }
> 
> Is that one evaluation, or up to four?
The reason I am curious is that I don't see how what I am doing is 
significantly different form techniques that make foliage for trees by 
using mesh with image_maps

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In article <4040e22a$1@news.povray.org>,
 Jim Charter <jrc### [at] msncom> wrote:

> Thankyou Christopher.  That makes sense. I think.  By normals you are 
> refering to the normals of the triangles in the mesh.

No, I'm talking about texture normals. You have four triangles, so a ray 
could intersect with four surfaces. If those surfaces have a non-solid 
texture and have a warp (including any transformation), the code will do 
up to four normal warps. More complex textures (for example, one with a 
texture_map) will need to do more. I'm not really sure why the code was 
written the way it was...but the nesting is from the point of view of a 
ray progressing into the scene, not a nesting in the scene specification.

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: <chr### [at] tagpovrayorg>
http://tag.povray.org/

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