In a layered texture, why does a normal-block in a second layer overwrite
the underlying, if that one has a normal applied? How to get around?

Why are some features of the finish overwritten, and some not? For example,
reflection is overridden by the new layer, but phong is not!

Example:
texture { pigment { color Green} finish { phong 1 phong_size 5 reflection
0 } }
texture { pigment { checker color rgbf 1 color rgbf 0 } finish { phong 1
phong_size 100 reflection 1 } }

This produces a green/black checkered texture which is all-reflective, even
at the green fields. But the dull phong-finish is preserved on the
underlying color.

Why is this so? I'd expect that the topmost finish/normal would be weighted
based on the filter/transparency of the color. But most important: How to
get around!

TIA
Simen.

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On Tue, 16 May 2000 00:02:59 +0200, "Simen Kvaal"
<sim### [at] studentmatnatuiono> wrote:

>In a layered texture, why does a normal-block in a second layer overwrite
>the underlying, if that one has a normal applied? How to get around?

Because layered textures are meant to represent a single surface. Try
giving the topmost layer a normal which is the average of the
underlying normals.

>Why are some features of the finish overwritten, and some not? For example,
>reflection is overridden by the new layer, but phong is not!

>Example:
>texture { pigment { color Green} finish { phong 1 phong_size 5 reflection
>0 } }
>texture { pigment { checker color rgbf 1 color rgbf 0 } finish { phong 1
>phong_size 100 reflection 1 } }

The topmost layer has reflection and so the texture is reflective
everywhere. The highlight is seen through the clear top layer.

>This produces a green/black checkered texture which is all-reflective, even
>at the green fields. But the dull phong-finish is preserved on the
>underlying color.

POV works as expected. Of course it does not necessarily match what
you want it to do :)

>Why is this so? I'd expect that the topmost finish/normal would be weighted
>based on the filter/transparency of the color. 

The layers in a texture are regular textures. A normal is just a
normal. If it is weighted according to transparency, how would one
engrave a glass ball? Same goes for the finish. Or are you suggesting
that texture layers are treated differently than regular textures?
This has its merits but will eventually have to be introduced as
optional so as not to break old scenes.

>But most important: How to get around!

For now, I think you can always get away with a (complex) patterned
texture. This is not always as easy, though.


Peter Popov ICQ : 15002700
Personal e-mail : pet### [at] usanet
TAG      e-mail : pet### [at] tagpovrayorg

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