On Mon, 25 Feb 2002 13:47:11 -0000, "Tom Melly" <tom### [at] tomandlucouk> wrote:

> I'm fairly sure that this has been reported before, but I can't see it mentioned
> in the most recent known bugs list. The red box specified last in the following
> code will disappear unless either Top_BC or Bottom_BC (or both) is/are commented
> out of the final union.
>
> The problem disappears with -UV

I found similiar but very strange problem today with sphere_sweeps. 

Here is scene to test this, look at comments:

camera{orthographic}

light_source{-100*z 1}

#local Show_Example=0; // render with 0..7, for 7 set -UV

#macro First(T)
  sphere_sweep{
    catmull_rom_spline 7
    <-0.50,0.25,0.50>.002
    <-0.25,0.00,0.50>.002
    < 0.00,0.25,0.50>.002
    <-0.25,0.50,0.50>.002
    <-0.50,0.25,0.50>.002
    <-0.25,0.00,0.50>.002
    < 0.00,0.25,0.50>.002
    pigment{color rgb 1}
    translate T*.5
  }
#end

#switch(Show_Example)
  #case(0)
    First(0)  // appear
  #break
  #case(1)
    First(x)  // appear
  #break
  #case(2)
    First(-y)  // appear
  #break
  #case(3)
    First(0)  // appear
    First(x)  // appear
  #break
  #case(4)
    First(0)  // appear
    First(-y)  // appear
  #break
  #case(5)
    First(x)  // appear
    First(-y)  // appear
  #break
  #case(6)
    First(0)  // disappear
    First(x)  // disappear
    First(-y)  // disappear
  #break
  #case(7)
    // with -UV
    First(0)  // appear
    First(x)  // appear
    First(-y)  // appear
  #break
#end

Any confirmation ?

POV 3.5 b 11 icl on WinNT Sp 6 PII 233 with 128 MB

ABX

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news:r6hk7usts1qgik8fiohe5r4gvb937hnj9e@4ax.com...

Hey! Get your own bug-report! ;)

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On Mon, 25 Feb 2002 15:27:32 -0000, "Tom Melly" <tom### [at] tomandlucouk> wrote:
> Hey! Get your own bug-report! ;)

I have a lot and I don't need another one ;)

ABX

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"Tom Melly" <tom### [at] tomandlucouk> wrote in message
news:3c7a4060@news.povray.org...

<snip>

Anyone want to confirm this/point out I'm an idiot for writing bad code/point
out I'm an idiot for reporting a known bug/other ?

Post a reply to this message

Tom Melly <tom### [at] tomandlucouk> wrote:
> Anyone want to confirm this/point out I'm an idiot for writing bad code/point
> out I'm an idiot for reporting a known bug/other ?

  Wasn't the effect of disappearing objects with orthographic camera a known
issue (which was related to the fact that with orthographic camera the rays
don't start from the camera location but from the projection plane)?

-- 
#macro N(D)#if(D>99)cylinder{M()#local D=div(D,104);M().5,2pigment{rgb M()}}
N(D)#end#end#macro M()<mod(D,13)-6mod(div(D,13)8)-3,10>#end blob{
N(11117333955)N(4254934330)N(3900569407)N(7382340)N(3358)N(970)}//  - Warp -

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On 26 Feb 2002 06:49:15 -0500, Warp <war### [at] tagpovrayorg> wrote:
>  Wasn't the effect of disappearing objects with orthographic camera a known
> issue (which was related to the fact that with orthographic camera the rays
> don't start from the camera location but from the projection plane)?

At least in my case it can be. What is current state of this problem ? Is this
a bug ? Design hole ? Feature ?
I wonder why -UV influences this.

ABX

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"Warp" <war### [at] tagpovrayorg> wrote in message news:3c7b763a@news.povray.org...
>
>   Wasn't the effect of disappearing objects with orthographic camera a known
> issue (which was related to the fact that with orthographic camera the rays
> don't start from the camera location but from the projection plane)?
>

That was my (very vague) recollection. Is this now considered a known problem,
rather than a bug? I couldn't see it on the bug list.

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news:9vtm7usbihgpqca9of5cshv7ieh94iacro@4ax.com...
>
> I wonder why -UV influences this.
>

IMHO POV thinks the objects are not visible, so doesn't render them. With the UV
flag, POV renders all objects whether visible or not, correcting the bug.

Hmm, if this bug cannot be resolved, is it possible to have POV automatically
render with "-UV" if the camera is orthographic (unless the user specifically
sets "UV")? If not, should something be added to the docs to warn users to use
"-UV" with ortho. to avoid problems (or if they experience problems)?

Post a reply to this message

On Tue, 26 Feb 2002 13:04:20 -0000, "Tom Melly" <tom### [at] tomandlucouk> wrote:
> IMHO POV thinks the objects are not visible, so doesn't render them. With the UV
> flag, POV renders all objects whether visible or not, correcting the bug.

Note UV flag turns vista buffer, right ? Documentation says it is "(...)
projecting the bounding box hierarchy onto the screen and determining the
rectangular areas that are covered by each of the elements in the hierarchy."
And it is correct with my case. Projection (screen) is parallel to xy and
cross point <0,0,1>. my object has z coordinates lower than 1 so vista buffer
exclude them. IIRC vista buffer is off by default when there is less than
three objects. So when I use two or one sphere sweep then only raw
intersection is checked. But then what Warp said? "(...) with orthographic
camera the rays don't start from the camera location but from the projection
plane". Then my sphere_sweeps shouldn't appear in any case.

ABX

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"Tom Melly" <tom### [at] tomandlucouk> wrote in message
news:3c7a4060@news.povray.org...
> I'm fairly sure that this has been reported before, but I can't see
it mentioned
[snip]

I think I've just encountered something similar in 3.5, my pruned
scene is below.

Gergely Vandor posted an ortho report 29/10/2001 and thread suggested
bug existed in 3.1g but with me 3.1g and Megapov 0.7 are OK although
angle is ignored with orthographic (angle seems to work with
orthographic in RC2).

Version 3.5.beta.RC2.msvc.win32.  Win98SE, Celeron 500, 160 MB

Alf

/*
 Is this an orthographic problem? Stats say 10 objects but none
rendered.
 Increase angle to 6, or comment orthographic, or comment yellow
spheres to show red sphere.
*/

#version 3.5;
camera { orthographic
         location <1.4, -0.05,-14>
         angle 5 look_at <1.4, -0.05, 0> }
light_source {-100*z rgb 1 }

#declare EEdata = array[9]
{
<1.601820,0.020981,0.000000>,
<1.501000,-0.006115,0.000000>,
<1.430000,-0.026420,0.000000>,
<1.380000,-0.039967,0.000000>,
<1.35, -0.066, 0>,
<1.380000,-0.093944,0.000000>,
<1.430000,-0.097113,0.000000>,
<1.501000,-0.096865,0.000000>,
<1.601820,-0.093170,0.000000>
}

sphere{ <1.35, -0.066, 0>, 0.035 pigment{ rgb <1,0,0> } }

#declare Cnt = 0;
#while (Cnt<9)
   sphere{ EEdata[Cnt], 0.03 pigment{ rgb <1,1,0> } }
   #declare Cnt = Cnt + 1;
#end

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