I just ran into a strange behaviour when trying to create multiple
copies of a mesh which had texture statements within the triangles.

Namely, I created a mesh wherein some of the triangles were given a
"corrugated metal" texture that was supposed to run parallel to the top
and bottom edges of the mesh.  (Other triangles within the mesh were
given a different texture.)  When only one copy of the mesh is used, it
works like it's supposed to.

However, when multiple copies are placed at different rotations, the
textures all show the same rotation as the first copy of the mesh.  If
the first mesh is rotated z*45, and the second is unrotated, its
triangles' textures are rotated by z*45.

The docs don't mention anything like this.  Is it supposed to happen?

If it matters, I'm using an unofficial compile of 3.1g for OS/2, but the
source is unchanged from the official Linux version.  It may very well
be that I've compiled it incorrectly, so if anyone's willing to try the
simplified example below on an official build, I'd be much obliged.


Extremely simplified example:

#declare T_Bumpy = texture {
  pigment { colour rgb <0.95,0.95,1.00> }
  finish { specular 1.0 roughness 0.005 brilliance 2 metallic }
  normal { gradient y scallop_wave scale 0.2 }
}

#declare SimpleMesh = mesh {
  triangle {<-0.5,0.5,0>,<0.5,0.5,0>,<-0.5,-0.5,0> texture {T_Bumpy}}
  triangle {<0.5,0.5,0>,<0.5,-0.5,0>,<-0.5,-0.5,0> texture {T_Bumpy}}
  // Other, differently textured triangles removed for simplicity's sake
}

object { SimpleMesh rotate z*45 }
object { SimpleMesh translate <1,1,1> }
camera { location <0,0,-6> look_at <0,0,0> angle 35 }
light_source { <-1000,1000,-1000> colour rgb <1,1,1> }
background { colour rgb <0.25,0.5,1> }


-- 
Jeff Lee         shi### [at] gatenet        http://www.gate.net/~shipbrk/

  "The only thing that helps me maintain my slender grip on reality
  is the friendship I share with my collection of singing potatoes."

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Jeff Lee wrote:

> However, when multiple copies are placed at different rotations, the
> textures all show the same rotation as the first copy of the mesh.  If
> the first mesh is rotated z*45, and the second is unrotated, its
> triangles' textures are rotated by z*45.
> 
> The docs don't mention anything like this.  Is it supposed to happen?

 This is a known bug and has been reported to the POV-Team. It will not
likely be fixed until the release of POV-Ray v3.5.

If you were not running OS2 I would point you toward the superpatch and
UVPov bothof which have this particular bug fixed. Source for both is
available I believe if you want to compile your own platform dependent
version.

-- 
Ken Tyler -  1200+ Povray, Graphics, 3D Rendering, and Raytracing Links:
http://home.pacbell.net/tylereng/index.html http://www.povray.org/links/

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