As we were playing around with image_maps and height_fields, I was 
reminded there is support for the keywords 'repeat' and 'offset' in the 
image_map and bump_map code.

These look useful to me in that they can accomplish what we usually do 
with scale and translate, without an actual transform. Anyone know why 
they are, since v3.7 at least, hidden from users? Or have I again missed 
some documentation?

Attached an image with traditional 'once' map on the left. In the middle 
using repeat <2,2> (how many/much in 1x1) and offset <0.5,0.5> 
(accounting for 2x repeats in 1x1).

On the right we go with repeat <3,3> only and add in the two repeat/flip 
tiling warps. I don't believe we can as easily accomplish this kind of 
tiling effect another way.

Aside: Those image_map repeat values can be any non integral positive 
(>0) float too.

Bill P.

//---
#declare Pigment00 = pigment {
     image_map { "p189crop.jpg"
         repeat <2,2>
         offset <0.5,0.5>
         map_type 0
         once
         interpolate 2
     }
   //warp { repeat x flip x }
   //warp { repeat y flip y }
}
//---

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