POV-Ray

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.

Tasklist

FS#113 - Multi-layered reflections broken

Attached to Project: POV-Ray
Opened by Christoph Lipka (clipka) - Friday, 14 May 2010, 20:42 GMT
Last edited by Christoph Lipka (clipka) - Saturday, 21 August 2010, 09:46 GMT
Task Type Definite Bug
Category Backend → Texture/Material/Finish
Status Closed
Assigned To Christoph Lipka (clipka)
Operating System All
Severity High
Priority High
Reported Version 3.70 beta 37a
Due in Version 3.70 beta 38
Due Date Undecided
Percent Complete 100%
Votes 0
Private No

Details

Reflections in multi-layered textures are broken in 3.7 betas, as can be demonstrated with the following scene showing two reflective hemispheres on a checkered plane:

camera {
  location  <1.0, 0.5, -4.0>
  direction 1.5*z
  right     x*image_width/image_height
  look_at   <0.0, 0.0,  0.0>
}

sky_sphere {
  pigment {
    gradient y
    color_map {
      [0.0 rgb <0.6,0.7,1.0>]
      [0.7 rgb <0.0,0.1,0.8>]
    }
  }
}

light_source {
  <0, 0, 0>            // light's position (translated below)
  color rgb <1, 1, 1>  // light's color
  translate <-30, 30, -30>
}

default {
 finish { diffuse 0 ambient 0 specular 0 }
}

// ----------------------------------------

plane {               // checkered floor
  y, -1
  texture
  {
    pigment { checker color rgb 1 color blue 1 }
    finish{ diffuse 0.8 ambient 0.1 }
  }
}

// left hemisphere
intersection {
  sphere { 0, 1 }
  plane { x, -0.002 }
  texture {
    pigment { color rgb 1 }
    finish{ reflection { 0.5 } }
  }
  texture {
    pigment { color rgbt 1 }
    finish{ reflection { 0.4 } }
  }
  texture {
    pigment { color rgbt 1 }
    finish{ reflection { 0.1 } }
  }
}

// right hemisphere
intersection {
  sphere { 0, 1 }
  plane { -x, -0.002 }
  texture {
    pigment { color rgb 1 }
    finish{ reflection { 1.0 } }
  }
}

Note that the reflection parameters of the left, multi-layered hemisphere sum up to 1.0, i.e. the same value as used in the single layer in the right hemisphere.

The first attached file (test_3.6.2.png), rendered with POV-Ray 3.6.2, shows the expected output: Both hemispheres appear to have the same reflectivity.

The second attached file (test_3.7.0.beta37a.png), rendered with POV-Ray 3.7.0.beta.37a, shows a much brighter left (multi-layered) sphere.

As it turns out, in order to get the expected result with POV-Ray 3.7.0.beta.37a, the reflectivity of each layer must be divided by 3, 2 and 1, respectively (which obviously does not sum up to 1.0):

  ...
  texture {
    pigment { color rgb 1 }
    finish{ reflection { 0.5 / 3 } }
  }
  texture {
    pigment { color rgbt 1 }
    finish{ reflection { 0.4 / 2 } }
  }
  texture {
    pigment { color rgbt 1 }
    finish{ reflection { 0.1 / 1 } }
  }
  ...
This task depends upon

Closed by  Christoph Lipka (clipka)
Saturday, 21 August 2010, 09:46 GMT
Reason for closing:  Fixed
Comment by Christoph Lipka (clipka) - Friday, 14 May 2010, 20:52 GMT
  • Field changed: Status (Investigating → Requires testing)
  • Field changed: Due in Version (Undecided → 3.70 beta 38)
  • Field changed: Percent Complete (0% → 100%)

fixed with change #4983

Comment by Grimbert Jérôme (Le_Forgeron) - Monday, 09 August 2010, 07:06 GMT

Tested with beta 38 source, original scene looks now fine.

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