The Persistence of Vision Raytracer (POV-Ray).
This is the legacy Bug Tracking System for the POV-Ray project. Bugs listed here are being migrated to our github issue tracker. Please refer to that for new reports or updates to existing ones on this system.
Attached to Project: POV-Ray
Opened by Christoph Lipka - 2009-11-08
Last edited by Thorsten Fröhlich - 2011-08-23
Opened by Christoph Lipka - 2009-11-08
Last edited by Thorsten Fröhlich - 2011-08-23
FS#66 - checker and cells pattern are slightly off-center
In POV-Ray 3.6 (including 3.62), checker and cells patterns are off by 0.001 (1e-3) units, as can be demonstrated with this scene:
camera {
location <0.0, 0.0, -5.0>
direction 1.5*z
right x*image_width/image_height
look_at <0.0, 0.0, 0.0>
}
box { <-1,-1,0>, <0,0,1> pigment { checker color rgb 1 color rgb 0 scale 0.2 translate <-0.5,-0.5,0> } finish { ambient 1 diffuse 0 } }
box { < 1, 1,0>, <0,0,1> pigment { checker color rgb 1 color rgb 0 scale 0.2 translate < 0.5, 0.5,0> } finish { ambient 1 diffuse 0 } }
box { < 1,-1,0>, <0,0,1> pigment { checker color rgb 1 color rgb 0 scale 200.0 translate < 0.5,-0.5,0> } finish { ambient 1 diffuse 0 } }
box { <-1, 1,0>, <0,0,1> pigment { checker color rgb 1 color rgb 0 scale 200.0 translate <-0.5, 0.5,0> } finish { ambient 1 diffuse 0 } }
The same can be demonstrated for the cells pattern.
POV-Ray 3.7 beta 34 is “clean”.
The offset was useful for the issue of "coincident surface like" that happen with a basic box { 0,1 }
It never was a good solution that scaled well.
IMHO, the basic error is in the design of the patterns: instead of centering around 0.5, spreading from 0 to 1, they should have been centered around integer values, +/- half.
It would have then stressed that to get a uniform unit box, the box should be a bit smaller (or the pattern scaled a bit bigger). As it was hidden from joe-user, it is on the long term counter-productive.
It's too late too change the centering, as it would break a lot of scenes, but getting ride of the offset is a good step.