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.

IDCategoryTask Type  ascReported InPrioritySeveritySummaryStatusProgressDue In Version
26Geometric PrimitivesDefinite Bug3.61Very LowLowArtifacts rendering a cloth which has two-side texturesTracked on GitHub
0%
Future release Task Description

Dear PovRay maintainers and developers, congratulations for your great RayTracer!

We think that we have found a bug while we were rendering a piece of cloth.

In this piece of cloth were defined two textures, one for one side and one for the another side:

  texture { mesh_tex0_0 }
  interior_texture { mesh_tex0_1 }
  • Please: Look at line 77414 of the attached file “test.pov” to see

these definitions in their original context.

We have found some artifacts in the final rendering, in concrete near some wrinkles,
please, look at the attached file “render_artifacts.tga”, I have painted a big green arrow
near the artifacts, maybe you’ll need to do a zoom to see them more accurately.

They are as though the texture of the other side was painted in the incorrect side.

Fortunately, we have a patch to fix this bug (thanks to Denis Steinemann, he made the
implementation for PovRay 3.5, so I have adapted these changes to release 3.6.1)

Although we have found this bug in the Windows and Linux 3.6.1 releases,
the patch was generated in Linux (using the source code release of “povray-3.6.1”).

To apply this patch, inside the parent folder of the directory “povray-3.6.1” execute:

            patch -p0 < other_side_artifacts.patch

And the “povray-3.6.1” will be patched and you will get a console output like this:

 patching file povray-3.6.1/source/lighting.cpp
 patching file povray-3.6.1/source/mesh.cpp
 patching file povray-3.6.1/source/render.cpp

We don’t know if this “hack” is enough smart to apply in the next release,
but we think that it fixes the bug (the artifacts dissapear).

Best regards and thank you very much for your great RayTracer!

60Geometric PrimitivesDefinite Bug3.70 beta 34Very LowMediumArtifacts using prism in CSGTracked on GitHub
0%
Future release Task Description

Using prisms in intersecion or difference CSG objects may cause artifacts in POV-Ray 3.6.2 as well as 3.7.0.beta.34, as demonstrated by the following code:


camera {
  right    -x
  up        y*image_height/image_width
  location  <-24,19,12>
  look_at   <0,0,0>
}

light_source { <100,200,100> color rgb 1 }

plane { y, -2 pigment { color rgb 1 } }


#declare KeyValue = 1.366; // pick any you like

difference {
  prism {
    linear_sweep -0.5,0.5, 4
    
    <-3,20-17>,
    <-3,KeyValue>,
    <-6,-3>,
    <-0,-5>
  }
  intersection {
    cylinder { <-7,-0.51,1>, <-7, 0.51,1>, 4.0 }
    plane { z, KeyValue }
  }
  pigment { color rgb 0.5 } 
}

Apparently the surface of the other object becomes visible when it exactly coincides with a vertex of the prism; probably there is a failure of the inside() test for such values.

196Subsurface ScatteringDefinite Bug3.70 RC3Very LowLowMore SSLT CaveatsTracked on GitHub
90%
Future release Task Description

when a prism is differenced with a primitive (cylinder in this case) if sslt is used it causes a seq fault. Reference distribution file logo.inc and the Povray_Logo_Prism definition.

222Geometric PrimitivesDefinite Bug3.70 RC3Very LowLowincorrect render of CSG merge with radiosityTracked on GitHub
0%
Future release Task Description

The problem arises when I am trying to trace a radiosity scene without conventional lighting that has a GSG merge object. There are a coincident surfaces, but these surfaces are first merged, then the texture applied. The texture is a simple solig color non-transfluent pigment, default normal, default finish etc..

Problem consists when adding antialiasing, changing resolution, changing camera view-point etc.; when I replace merge with union, the problem disappeared.

The scene was checked on two different machines with different versions of POV-Ray:

  1. Gentoo Linux, kernel 2.6.39-r3, i686 Intel(R) Xeon(TM) CPU 2.80GHz GenuineIntel, 2G RAM (this is Dell PowerEdge 2650 server with 2 dual-core Intel Xeon MP processors); Persistence of Vision™ Ray Tracer Version 3.7.0.RC3 (i686-pc-linux-gnu-g++ 4.5.3 @ i686-pc-linux-gnu)
  2. Gentoo Linux, kernel 2.6.37-r4, x86_64 AMD Athlon™ X2 Dual Core Processor BE-2350, 2G RAM (non-branded machine); Persistence of Vision™ Ray Tracer Version 3.6.1 (x86_64-pc-linux-gnu-g++ 4.4.4 @ x86_64-pc-linux-gnu)

(scene has been adapted slightly to be rendered with 3.6, the adaptation was to change “emission” with “ambient” and replace gamma “srgb” with “2.2”)

Both machines generate similar images.

The attachment is an archive containing sources of minimal scenes with these problems, and sample pictures I generated from them on my machines.

275Light sourceDefinite Bug3.70 RC7Very LowLowcircular area lights exhibit anisotropyTracked on GitHub
50%
Future release Task Description

circular area lights exhibit some anisotropy, being brighter along the diagonals than on average, as can be demonstrated with the following scene:

//+w800 +h800
#version 3.7;
global_settings{assumed_gamma 1}
plane{-z,-10 pigment{rgb 1} finish{ambient 0 brilliance 0}}
disc{0,z,10000,0.5}
camera{orthographic location z look_at 10*z up y*12 right x*12}
light_source{-10*z rgb 10 area_light 10*x 10*y 257 257 adaptive 4 circular}
287Light sourceDefinite Bug3.70 RC7Very LowLowarea_illumination shadow calculationTracked on GitHub
50%
Future release Task Description

not sure if this is something needing further work or an intended effect.

Shadows from and area light with area_illumination on seem to follow the same shadow calculation as a standard area light by giving more weight to lights near the center of the array. I would assume the shadows would be calculated similarly to individual lights in the same pattern as the array by evenly distributing the amount of shadow equally for each light. But this is not what I see.

The code sample below when rendered with scene 1 will show shadows grouped near the center from the area light with area_illumination. If scene 1 is commented out and scene 2 is uncommented then rendered, you will see evenly distributed shadows from individual lights. Area lighting with area_illumination I would assume should give a result identical to scene 2. If scene 1 is rendered with area_illumination off, the shadow calculation is exactly the same as with area_illumination on.

example images rendered on win32 XP

#version 3.7;

global_settings {
 ambient_light 0
 assumed_gamma 1
}

camera {
  location <0, 3, -5>
  look_at <0, 2, 0>
}

background { rgb <.3, .5, .8> }
plane { y,0 pigment { rgb .7 } }
torus { 1.5,.1 rotate 90*x translate 4*z pigment { rgb .2 } }
plane { -z,-7 pigment { rgb .7 } }

/*
// scene 1
light_source{
  y
  1
  area_light 3*x, z, 7, 1
  area_illumination on
}
union {
 sphere { 0,.05 }
 sphere { .5*x,.05 }
 sphere { x,.05 }
 sphere { 1.5*x,.05 }
 sphere { -.5*x,.05 }
 sphere { -x,.05 }
 sphere { -1.5*x,.05 }
 translate y
  hollow pigment { rgbt 1 } interior { media { emission 10 } }
}
// end scene 1
*/


// scene 2
#declare Light = light_source {
  0
  1/7
  looks_like { sphere { 0,.05 hollow pigment { rgbt 1 } interior { media { emission 10 } } } }
}

union {
 object { Light }
 object { Light translate .5*x }
 object { Light translate x }
 object { Light translate 1.5*x }
 object { Light translate -.5*x }
 object { Light translate -x }
 object { Light translate -1.5*x }
 translate y
}
// end scene 2

296Geometric PrimitivesDefinite Bug3.70 RC7DeferMediummax gradient computation is not thread safe (isosurface...Tracked on GitHub
0%
3.71 release Task Description

It appears as a side effect of investigation of #294: the code in isosurf.cpp, inside
bool IsoSurface::Function_Find_Root_R(ISO_ThreadData& itd, const ISO_Pair* EP1, const ISO_Pair* EP2, DBL dt, DBL t21, DBL len, DBL& maxg)

	if(gradient < temp)
		gradient = temp;

is not thread-safe (The code is used at render time, there is a data race between < and = operation, as gradient is stored in the global object and accessed in write mode by the cited code)

It is only important if the gradient is initially undervaluated (otherwise, all is fine, no write-access)

306Subsurface ScatteringDefinite Bug3.70 RC7Very LowHighfinish subsurface block before global_settings subsurfa...Tracked on GitHub
0%
3.71 release Task Description

The following scene causes a crash:

sphere {
  <0,0,0>, 1
  finish { subsurface { translucency 1.0 } }
}

global_settings {
  subsurface { }
}
309Parser/SDLDefinite Bug3.70 RC7Very LowLowWarning Message MissingTracked on GitHub
0%
3.71 release Task Description

Draw_Vistas, Light_Buffer, and Vista_Buffer (plus associated switches) do not issue warning when used, even tho code has been disabled.

25AnimationDefinite Bug3.70 beta 32DeferLowPause sometimes fails when rendering animationTracked on GitHub
90%
Task Description

There is an issue where the pause button in POVWIN will sometimes not work during an animation (primarily where the frame rate is high), and furthermore, POVWIN can then get into a state where it’s not possible to use the pause until it is re-started.

Newsgroup report.

42OtherDefinite Bug3.70 beta 32Very LowMediumcommand line parameters are not parsed properly on UnixTracked on GitHub
0%
Task Description

POV-Ray does not follow common practice on command-line handling; for instance:

povray +i"My File"

entered on a Unix shell would be passed to POV-Ray as

povray
+iMy File

(each line representing a distinct parameter here), which POV-Ray would further dissect, interpreting it as

povray
+iMy
File

To achieve the desired effect, one would actually have to quote the string twice:

povray +i"'My File'"

which the shell would translate to

povray
+i'My File'

which POV-Ray would interpret as

povray
+iMy File

In both cases, this is obviously not what a Unix user would expect.

The further dissecting of individual command-line parameters may have had its valid roots in the peculiarities of DOS’ command-line handling, but to my knowledge all major contemporary operating systems follow a concept akin to Unix, passing a list of parameters instead of a monolithic command line, and burdening the respective command shells with the task of dissecting command lines into parameters.

Therefore I suggest to disable this anachronistic feature in favor of contemporary standards; a compiler flag might be used to allow for easy re-enabling of the feature, for compiling POV-Ray on exotic targets.

- edit -

It has been pointed out that the described behaviour differs from 3.6, so I’m promoting this to a bug and changing the title.

81Geometric PrimitivesDefinite Bug3.62Very LowMediumsphere_sweep generating artifactsTracked on GitHub
0%
Task Description

I’m running POV-Ray for (64 bit) Windows v3.62 on (64 bit) Windows Vista

This pov file:


#include "colors.inc"
#include "metals.inc"

light_source { <6, 9, -21> color White }
camera { location <0, 0, -3> look_at <0, 0, 0> }

sphere_sweep {
                cubic_spline
                6
                <-2.0, 0, 0> 0.05

                <0.000,0,0> 0.2
                <0.025,0,0> 0.2
                <0.050,0,0> 0.2
                <0.075,0,0> 0.2

                <3.0,0,0> 0.2
                pigment { color White }
}

Produces two strange artifacts: A disk at the center of the sweep, and a faint “halo” or veil which shows as 4 faint hyperbolas centered around the origin.

I have tried tweaking tolerance (for no other reason than I saw that someone else was tweaking it to solve a problem) but this does not seem to change things.

For a look at MY result when I run this, view this image:

riventree.comarchivebugdatapovrayspheresweepartifacts.jpg

Alain reports the same behavior in the latest version: “It’s still there with the latest version: 3.7 beta 35a.” This MAY move the status to “confirmed”, but I can’t do that

Someone else says that changing the scale (!) “solves” the problem by moving the disk and the halo offscreen, but that sounds like a bad idea to me.

-Jeff Evarts, first-time POVRay bug reporter

202Geometric PrimitivesDefinite Bug3.70 RC3Very LowLowNumerical oddities in Julia_FractalTracked on GitHub
0%
Task Description

I understand that some things have changed in the way certain computations in POV-Ray decide when something is “good enough” and I think this is biting me in Julia_Fractal (where, of course, the highest-resolution computations are needed).

The bug has been posted here:

http://news.povray.org/povray.bugreports/thread/%3Cweb.4dbf2e26b56a53c15b4449250%40news.povray.org%3E/

Including a short .pov file and instructions that reproduce it.

(It pops up in other configurations and view angles as well, but this one captures in in a way that makes it clear it’s a bug: the distance of the camera from the origin appears to change the shape of the rendered object).

This appeared first on a Windows Server 2003 machine, it is apparently confirmable on at least one other system as per that thread.

237User interfaceDefinite Bug3.70 RC3DeferVery LowGlitch in displaying rendered pixels and percentageTracked on GitHub
0%
Task Description

When rendering in multiple passes (radiosity in my case), the elapsed pixels and percentage, written to terminal
are first displayed like this:
Rendered 126202 of 360000 pixels (35%)
Then on the second stage the output text becomes shorter and you see
Rendered 25344 of 360000 pixels (7%)%)
The contents of the previous status are not erased, so the longer text persists (note the duplicate percentage sign and closing parenthesis). Such a glitch could have more drastic effect in rare cases.

I’m running
Version 3.7.0.RC3 (g++ 4.6.2 x86_64-unknown-linux-gnu)
compiled for the Arch Linux package.

252PhotonsDefinite Bug3.70 RC6Very LowLowphotons and light_group is brokenTracked on GitHub
0%
Task Description

photons are not working when used with a light_group. verified in NG posting in p.general a simple scene file is attached.

273OtherDefinite Bug3.70 RC6Very LowMediumNo automatic backup files from inc filesTracked on GitHub
0%
Task Description

If enabled, POVray always created backups of pov and inc files once per session.
Now using 3.7 RC6 only pov file backups are created but not from inc files.

295User interfaceDefinite Bug3.70 RC7Very LowLowMinor GUI BugsTracked on GitHub
0%
Task Description

Here are two low-priority bugs in POV-Ray’s GUI, observed by me under Windows XP, which should be easy to fix I think:

  • In the “Insert” menu, there are sub-menus (e.g. “Radiosity and Photons”) in which there are menu seperators at the end of the popped-up menu bar.
  • The progress bar in the top-right corner of the editor window seems to be too large for the window (203px) and therefore clipped. As a result, progress seems to be 100% when it is not yet, e.g. at 90% progress. (Have not measured exactly.)

Both bugs are not severe at all, but it would be nice if they could be fixed.
By the way, a second progress bar could be added to visualize the number of frames already rendered in an animation.

301OtherDefinite Bug3.70 RC7Very LowLowFallback to default image size causes wrong values to b...Tracked on GitHub
50%
Task Description

When resolution is not specified (neither via POVRAY.INI nor via QUICKRES.INI nor via command line or custom .ini file), random values are displayed for image resolution in the Image Output Options message output. (The actual render will be performed at the default size of 160×120 pixels though.)

303OtherDefinite Bug3.70 RC7DeferVery Lowwrong bit depth reported for OpenEXR file formatTracked on GitHub
0%
Task Description

When using OpenEXR output file format, POV-Ray erroneously reports it as “24 bpp EXR” in the message output, while in fact it generates a 3×16 = 48 bpp file.

313RadiosityDefinite Bug3.70 releaseLowHighradiosity.cpp pov::RadiosityFunction::BeforeTile assert...Tracked on GitHub
20%
Task Description

With 3.7.0 final, rendering attached files (for Computer Engineering college course),
which renders without issues in povray 3.6.1, fails with following error:

...
==== [Rendering...] ========================================================
povray: backend/lighting/radiosity.cpp:324: virtual void pov::RadiosityFunction::BeforeTile(int, unsigned int): Assertion `(pts >= PRETRACE_FIRST) && (pts <= PRETRACE_MAX)' failed.

Command line:

povray +K0.6500 \
+FN +Q9 +MB1 \
+W600 +H400 \
+AM1 +A0.0 +R2 \
+D +SP32 +EP4 \
+L/usr/share/povray-3.7/include \
+Imain.pov \
+Omain-0.6500.png

Using Arch Linux testing current:
Linux archmidi 3.12.0-1-ARCH #1 SMP PREEMPT Wed Nov 6 09:06:27 CET 2013 x86_64 GNU/Linux

Downstream bug report:
https://bugs.archlinux.org/task/37689

321OtherDefinite Bug3.70 releaseVery LowLowbounding threshold inconsistencyTracked on GitHub
90%
Task Description

User reported documentation inconsistency. Investigation led to the discovery of a bug in the setting of the current default value.

~source/frontend/renderfrontend.cpp reports the value “3” while ~source/backend/scene/scene.cpp sets a default value of “1”

Before for addressing this issue, are there any thoughts as to what the default value should be?

324Geometric PrimitivesDefinite Bug3.70 releaseVery LowHigh3.7 mesh2 rendering artifact, regression from 3.6Tracked on GitHub
0%
Task Description

Povray 3.7 has rendering artifact in meshes with polygons that meet at shallow angles. Please see the attached file.

The part of concern is the mesh2, which produces the partly-transparent faces of a shallow pyramid. The file result-3_6.png shows the output of povray-3.6, and the file result-3_7.png shows the output of povray-3.7. In 3.7, you can see a thin light-colored margin all around the base of the pyramid, especially thick under the top cylinder. In 3.6, this artifact is absent. For comparison purposes, I have inserted a “#version 3.6;” directive at the top of the file so that the output images are as close to each other as possible. However, the artifact is still present in 3.7 without this directive.

The attached scene file is only a small part of a much larger scene, where this artifact shows up in numerous very obvious places, where it doesn’t in 3.6. I have hunted in the documentation and online for ways to solve this problem, but haven’t found anything. Because of this, I am forced to stay with 3.6 for production use, which is quite unfortunate since I’d like to take advantage of the new features of 3.7.

326OtherDefinite Bug3.70 releaseVery LowLowrestricted setting ignored in 3.7Tracked on GitHub
0%
Task Description

Due to a typo in the conf file parser (introduced, I think, in refactoring after 3.6), the restricted setting is ignored, and access checks aren’t performed.

Fixing this reveals some other issues:

  • %INSTALLDIR%/../../etc is incompletely canonicalized to /usr/local/share/../etc, not /usr/local/etc
  • read+write paths are added to the read list only, so writing is impossible

See attached patch.

Relatedly, I think it would be nice to add a new replacement token %CONFDIR% instead of %INSTALLDIR%/../../etc.

Also, there’s a realpath function that could simplify path handling, though I’m not sure if it’s available on all platforms.

328User interfaceDefinite Bug3.70 releaseVery LowMediumAscii char '=' in filenames causes command line parsing...Tracked on GitHub
0%
Task Description

The following command fails with parsing error:
povray +OqXfFbD0Vg5XjZgi5sOefkvdF_oCGrZ1ChVhrQw==.png +IqXfFbD0Vg5XjZgi5sOefkvdF_oCGrZ1ChVhrQw==.pov +W1000 +H1000

The following command succeeds:
povray +OqXfFbD0Vg5XjZgi5sOefkvdF_oCGrZ1ChVhrQw.png +IqXfFbD0Vg5XjZgi5sOefkvdF_oCGrZ1ChVhrQw.pov +W1000 +H1000

Any option that gets a filename as parameter will fail if it contains ‘=’.

It is a regression, as it worked fine with 3.6.

27OtherFeature Request3.70 beta 32Very LowLowAdd texture support to background statementTracked on GitHub
0%
Future release Task Description

Adding full texture statement support to the background statement (with a scale of 1/1) aligned with the image_map direction of an image would allow i.e. specifying an image as background easily.

28FrontendFeature Request3.70 beta 32Very LowLow#debug message not displayed.Tracked on GitHub
0%
Future release Task Description

The #debug message stream is only being flushed when it hits a newline character,
instead of after each #debug statement. This means that some final strings don’t show up.

#debug "This line prints,\n but this line doesn't."
44RadiosityFeature RequestAllVery LowLowImprove Normals Handling in RadiosityTracked on GitHub
0%
Future release Task Description

Currently, radiosity does not make use of the fact that pertubed normals would theoretically just require a different weighting of already-sampled rays, leading to the following issues:

  • Honoring normal pertubations in radiosity leads to an increased number of samples, slowing down sample cache lookup.
  • The increased number of samples is generated from a proportionally higher number of sample rays, slowing down pretrace even further.
  • Low-amplitude pertubations tend to be smoothed out; “reviving” these is only possible by increasing the general sample density.
  • Handling of multi-layered textures with different normal pertubations is currently poorly implemented.

As a solution, I propose to store for each radiosity sample not only the resulting illumination for a perfectly unpertubed normal, but from the same set of sample rays also compute the illumination for an additional set of about a dozen standardized pertubed-normal directions, and interpolate among these when computing the radiosity-based illumination for a particular point that has a pertubed normal.

For backwards compatibility, this method of dealing with pertubed normals in radiosity might be activated by a different value for the “normal” statement in the radiosity block, say, “normal 2”.

65Parser/SDLFeature Request3.70 beta 34Very LowLowAdd support for vectors with functionsTracked on GitHub
0%
Future release Task Description

Being able to have functions operate on vectors would be pretty nice to have.

79Source codeFeature Request3.70 beta 35aVery LowLowFull-Featured Test-Scene to check the correctness of po...Tracked on GitHub
0%
Future release Task Description

Hi,

it would be nice if there exists a test scene (not a benchmark) which has a high coverage of povray source and can be used as correctness validation of povray. It schould be produce an image which can be compared to a golden reference image.

It may be also possible to create a regression test suite which does automatic comparision of the render results.

85OtherFeature RequestNot applicableDeferLowAspect ratio issuesTracked on GitHub
0%
Future release Task Description

Background

When rendering an image, there are actually three aspect ratios involved:

1) The aspect ratio of the camera, set with the up and right vectors.

2) The aspect ratio of the rendered image, set with the +W and +H parameters.

3) The aspect ratio of the pixels in the intended target medium. While this is very often 1:1, it’s definitely not always so (anamorphic images are common in some media, such as DVDs).

The aspect ratio of the camera does not (and arguably should not, although some people might disagree) define the aspect ratio of the image resolution, but the aspect ratio of the image as shown on the final medium. In other words, it defines how the image should be displayed, not what the resolution of the image should be.

This of course means that the aspect ratio of the target medium pixels has to be taken into account when specifying the image resolution. If the target medium pixels are not 1:1 (eg. when rendering for a medium with non-square pixels, or when rendering an anamorphic image eg. for a DVD), the proper resolution has to be specified so that the aspect ratio of the displayed image remains the same as the one specified in the camera block.

This isn’t generally a problem. It usually goes like “my screen is physically 4:3, so I design my scene for that aspect ratio, but the resolution of my screen is mxn which is not 4:3, but that doesn’t matter; I just render with +Wm +Hn and I get a correct image for my screen”.

However, problems start when someone renders an image using an image aspect ratio / pixel aspect ratio combination which does not match the camera aspect ratio. By far the most common situation is rendering a scene with a 4:3 camera for a screen with square pixels but with a non-4:3 resolution (most typically 16:9 or 16:10 nowadays). The image will be horizontally
stretched.

In a few cases the effect is the reverse: The scene (and thus the camera) has been designed for some less-typical aspect ratio, eg. a cinematic 2.4:1 aspect ratio, but then someone renders the image with a 4:3 resolution. The resulting image will be horizontally squeezed.

In a few cases this is actually the correct and desired behavior, ie. when you are really rendering the image in an anamorphic format (eg. for a DVD). However, often it’s an inadverted mistake.

Some people argue that this default behavior should be changed. However, there are also good arguments why it should not be changed. Some argue that POV-Ray should have more features (at the SDL level, at the command-line level or both) to control this behavior.

There are several possible situations, which is why this issue is so complicated. These situations may include:

- The scene author doesn’t really care what aspect ratio is used to render the image, even if it means that additional parts of the scenery become visible or parts are cropped away when using a different aspect ratio than what he used.

In this case the choice of camera aspect ratio should be up to the person who renders the image, and thus selectable on the command-line. However, he should have an easy choice of how changing the aspect ratio affects the image: Should it extend the viewing range, or should it crop part of it, compared to the original?

And this, of course, while still making it possible to render for an anamorphic format.

- The author wants to support different aspect ratios, but he wants to control precisely how it affects the composition of the image. Maybe he never wants anything cropped away within certain limits, but instead the image should always be extended in whichever direction is necessary due to the aspect ratio. Or maybe he wants to allow cropping the image, but only up to a certain point. Or whatever.

In this case the choice of camera aspect ratio should be up to the author, and thus selectable in the scene file, while still allowing some changes from the command-line.

- The author designed his scene for a precise aspect ratio and nothing else, and doesn’t want the image to be rendered in any other aspect ratio. Maybe he used some very peculiar aspect ratio (eg. something like 1:2, ie. twice as tall as wide) for artistic composition reasons, and wants the image rendered with that aspect ratio, period.

Perhaps the author should be able to completely forbid the change of camera aspect ratio in the command-line.

Of course anamorphic rendering should still be supported for targets with a different pixel aspect ratio.

Possible solution

This solution does not necessarily address all the problems described above perfectly, but could be a good starting point for more ideas:

Add a way to specify in the camera block minimum and maximum limits for the horizontal and vertical viewing angles (and if any of them is unspecified, it’s unlimited). Of course for this to be useful in any way, there should also be a way to change the camera and pixel aspect ratios from the command line.

The idea with this is that the author of the scene can use these angle limits to define a rectangular “protected zone” at the center of the view, using the minimum angle limits. In other words, no matter how the camera aspect ratio is modified, the horizontal and/or vertical viewing angles will never get smaller than these minimum angles. This ensures that the image will never be cropped beyond a certain limit, only extended either horizontally or vertically to ensure that the “protected zone” always remains fully visible regardless of what aspect ratio is used.

The maximum angles can be used for the reverse: They ensure that no scenery beyond a certain point will ever become visible, no matter what aspect ratio is used. This can be used to make sure that unmodelled parts of the scene never come into view. Thus the image will always be cropped to ensure this, depending on the aspect ratio.

I’m not completely sure what should be done if both minimum and maximum angles are specified, and the user specifies an aspect ratio which would break these limits. An error message could be a possibility. At least it would be a way for the author to make sure his scene is never rendered using an aspect ratio he doesn’t want. He can use these angle limits to give some leeway how much the aspect ratio can change, to an extent, or he could even force a specific aspect ratio and nothing else (by specifying that both the minimum and maximum angles are the same).

So in short:

- Add a “minimum/maximum horizontal/vertical angles” feature to the camera block. These can be used to define a “protected zone” in the image which must not be breached by command-line options.

- Add a command-line syntax to change the camera aspect ratio (which automatically obeys the “protected zone” settings). Could perhaps give an error message if the command-line options break the limits in the scene camera.

- Add a command-line syntax to specify a pixel aspect ratio other than 1:1. This can be used to render anamorphic versions of the image on purpose (iow. not by mistake).

This can probably be made backwards-compatible in that if none of these new features are used, the behavior could be the same as currently (or at least similar).

86Parser/SDLFeature RequestNot applicableDeferVery LowAdd support for more RNG typesTracked on GitHub
0%
Future release Task Description

The current 32-bit linear congruential generator used as RNG in POV-Ray is sometimes quite limited for some purposes and in a few cases its poor quality shows up (as has been demonstrated more than once in the newsgroup). Thus it would be nice if POV-Ray offered additional, higher-quality random number generators, besides the current one (which should probably remain for backwards compatibility). These RNGs could include algorithms like the Mersenne Twister and the ISAAC RNG, both of which have very decent quality and have an enormous periods (while at the same time being very fast).

After a long discussion, the following syntax for specifying the RNG type and seed (which may be larger than 32 bits) has been suggested:

seed(<value>) | seed(<type>, <value> [, <values>])

For example:

#declare Seed1 = seed(123); // Use the current RNG, with seed 123
#declare Seed2 = seed(1, 123); // Identical to the previous one
#declare Seed3 = seed(2, 456, 789, 123); // Use RNG algorithm #2,
                                         // with a large seed (96 bits specified here)

A C++ implementation of the ISAAC RNG can be found at http://warp.povusers.org/IsaacRand.zip

87Geometric PrimitivesFeature RequestNot applicableDeferVery LowAdd new feature: Reference objectTracked on GitHub
0%
Future release Task Description

When you instantiate an object several times, eg:

object { MyObj translate -x*10 }
object { MyObj translate x*10 }

POV-Ray will copy that object in memory, at least for most types of objects. Not for all of them, though. Most famously if MyObj is a mesh, it won’t be copied, but only a reference to the original will be used, thus saving memory. (There are a few other primitives which also don’t cause a copy, such as bicubic_patch and blob, but those are naturally not so popular as mesh, so it’s a less known fact.)

AFAIK the reason why referencing (rather than copying) is not used for all types of objects is rather complicated, and mostly related to how transformations are applied to these objects. For example if the object being instantiated is a union, the translates above will be (AFAIK) applied to the individual members of the union rather than to the union object itself.

Copying, however, can be quite detrimental in some situations. For example if you have a huge union, and you want to instantiate it many times, the memory usage will be that many times larger (compared to just one instance). This is sometimes something which the user would not want, even if it made the rendering slightly slower as a consequence. (In other words, better to be able to render the scene in the first place, rather than running out of memory.)

Redesigning POV-Ray so that all objects would be referenced rather than copied would probably be a huge job, and in some cases a questionable one. There probably are situations where the current method really produces faster rendering times, so redesigning POV-Ray so that it would always reference instead of copy, could make some scenes render slower.

So this got me thinking about an alternative approach: How hard would it be to create a special object which sole purpose is to act as a reference to another object, without copying it? This special reference object would act as any regular object, would have its own transformation matrix and all that data related to objects, but its sole purpose is to simply be a “wrapper” which references an existing object. It could be, for example, like this:

object_ref { MyObj translate -x*10 }
object_ref { MyObj translate x*10 }

The end result would be exactly identical as earlier, but the difference is that now MyObj behaves in the same way as a mesh (in the sense that it’s not instantiated twice, but only once, even though it appears twice in the scene), regardless of what MyObj is.

In some cases this might render slightly slower than the first version (because POV-Ray has to apply the transformations of the object_ref first, after which it applies whatever transformations are inside MyObj), but that’s not the point here. The point is to save memory if MyObj is large.

An object_ref would behave like any other object, so you could do things like:

#declare MyObjRef = object_ref { MyObj };

object { MyObjRef translate -x*10 }
object { MyObjRef translate x*10 }

(The only thing being instantiated (and copied) here is the “MyObjRef” object, not the object it’s referring to, so that actual object is still stored in memory only once.)

In some situations it might even be so that referenced objects actually render faster than if the objects were copied because references increase data locality, lessening cache misses.

I believe this could be a rather useful feature and should be seriously considered, unless there are some major obstacles in implementing it.

91Texture/Material/FinishFeature Request3.70 beta 36DeferLowSlope pattern applied to object is not transformed afte...Tracked on GitHub
0%
Future release Task Description

There is an big issue with the slope pattern: when the object it is applied to is instanced (again) with a transformation (in particular a rotation, as a translation would not impact.. but a shear might), the colours of the surfaces are changed.

  
object { p translate -5*x }
object { p rotate 220*y+20*x    translate 3*x }       

Nobody would expect the object to be different in appearance.
If slope {} is replaced with wood, all is fine. (as for others textures, i guess)

IMHO, the slope vector need to be adjusted for the later transformation(s) (so as to compensate the issue of using the Perturbed Normal vector).

This should not impact the AOI/FACING (experimental) patterns, as AOI definition is pretty clear about duplicating & transform if you think about it a bit, as well as FACING: for these two, it is expected to either use the ray(current point of view) or a fixed 3D point as reference. At the limit, discussion about moving the 3D point of FACING might also be opened to interpretation.

AOI/FACING are in task #19

96Texture/Material/FinishFeature RequestNot applicableVery LowLowUser-defined warpsTracked on GitHub
0%
Future release Task Description

User-defined warps would be nice to have, something along the lines of:

warp {
  function { MyFnX(x,y,z) } // function to compute pattern-space x-coordinate from object-space <x,y,z> coordinate
  function { MyFnY(x,y,z) } // ditto for pattern-space y coordinate
  function { MyFnZ(x,y,z) } // ditto for pattern-space z coordinate
}

// a displacement warp:
warp {
  function { x + MyFnX(x,y,z) }
  function { y + MyFnY(x,y,z) }
  function { z + MyFnZ(x,y,z) }
}
108Parser/SDLFeature Request3.70 beta 37Very LowLowmotion_blur feature similar to Megapov versionTracked on GitHub
0%
Future release Task Description

motion_blur which is a simple and effective feature to use in Megapov to simulate motion blur of, e.g. bird wings, propellers or running animals, would be a neat addition to version 3.7 and later.

In Megapov, the feature requires a line of code in the global_settings{} e.g.: motion_blur 10, 2
and a declaration for the moving object. e.g.:

motion_blur {
  type 0
  object{MyObject  material{MyMaterial rotate x*clock*2}}
  rotate x*clock*10
}

type represents several types of pre-defined motions.

Thanks,

Thomas

115Texture/Material/FinishFeature Request3.70 beta 37aVery LowLowMore cutaway_texturesTracked on GitHub
0%
Future release Task Description

Think this is still a problem. See the attached scene file. Find the WindowFrameSegment declaration for more info. The scene as-is shows the problem (SOME portions of the difference inherit the color of the room) the window opening is scaled larger to show that they AREN’T touching. The problem goes away when (in WindowFrameSegment) the 1st occurrence of the applied texture is commented out and the 2nd occurrence is uncommented, and cutaway_textures is commented out.

127Parser/SDLFeature Request3.70 beta 37aVery LowLowExpandable arraysTracked on GitHub
0%
Future release Task Description

Currently, arrays are of a fixed size. You can’t add or remove items to/from an array. I think it would like arrays to be expandable with no fixed and pre-determined size.

129Parser/SDLFeature Request3.70 beta 37aDeferVery LowHash arraysTracked on GitHub
0%
Future release Task Description

Currently, array items may only be referenced by their index number (an integer). It would be nice to also be able to assign string values as array indexes, as in other scripting languages.

131OtherFeature Request3.70 beta 37aVery LowLowAbility to change the order of editor tabs by dragging ...Tracked on GitHub
0%
Future release Task Description

See Notepad++ or EditPad Lite for examples.

It would be nice to be able to drag tabs in the editor window to change their order, so as to group opened files together by relevance for instance.

133Geometric PrimitivesFeature Request3.70 beta 37aDeferVery LowSubdivision supportTracked on GitHub
0%
Future release Task Description

Someone built a version of Povray with internal support for automatic subdivision of meshes. See:

http://www.cise.ufl.edu/~xwu/Pov-Sub/

Would like to see this feature added natively to Povray.

142Texture/Material/FinishFeature Request3.70 beta 37aVery LowLowcamera_view pigment from MegaPOVTracked on GitHub
0%
Future release Task Description

I probably don’t have to explain why the camera_view pigment in MegaPOV was important, but I will list some reasons anyway:

1) post-processing could be performed in-scene
2) new types of focal blur effects could be created
3) feedback fractals were possible

I’m sure there are many others, as this is one of those features that has undetermined potential!

245OtherFeature RequestAllDeferLowPOVMS message queue can fill up with GB of data for ver...Tracked on GitHub
0%
Future release Task Description

With very fast renders and very large output files, the message queue can fill up because the producers are not limited by IO, while the consumer performance is limited by disk IO. Consequently, the message queue can fill up to exhaust all available memory. The solution is to build in some better control of pending output data in the message queue on the producer side. This will also pave the way for message communication over slow links (i.e. a network).

248Parser/SDLFeature RequestNot applicableVery LowLowImplement mechanism to compute direction of a splineTracked on GitHub
0%
Future release Task Description

The SDL currently provides no way to compute the exact direction of a spline at a given location, even though mathematically this is a piece of cake: The first-order derivative of any spline section gives you the “speed” as a vector function, and is trivial to compute for polynomial splines (which are behind all spline types that POV-Ray supports); the normalized “speed” vector, in turn, gives the “pure” direction.

For exact direction/speed computations, I propose to extend the SDL invocation syntax as follows to allow for evaluating a spline’s derivative:

    SPLINE_INVOCATION:
        SPLINE_IDENTIFIER ( FLOAT [, SPLINE_TYPE] [, FLOAT] )

or

    SPLINE_INVOCATION:
        SPLINE_IDENTIFIER ( FLOAT [, FLOAT] [, SPLINE_TYPE] )

where the second FLOAT will specify the order of derivative to evaluate (defaulting to 0). In order to compute the position, direction, and acceleration of an object traveling along a certain spline, one could then for instance use:

    #declare S        = spline { ... }
    #declare Pos      = S(Time);
    #declare VSpeed   = S(Time,1);
    #declare VAccel   = S(Time,2);
    #declare Dir      = vnormalize(VSpeed);
    #declare Speed    = vlength(VSpeed);
    #declare AccelDir = vnormalize(VAccel);
    #declare GForce   = vlength(VAccel) / 9.81;

Alternatively, a mechanism may be devised to create a spline representing another spline’s derivative; however, it would be debatable whether the syntax should be parameter-like (being an added information that could be overridden again when creating other splines from such a derived spline), or operation-like (converting the spline), and in the latter case how it should affect spline type (and consequently control points); so the spline invocation parameter approach might be more straightforward, with less potential surprises for the user.

281Geometric PrimitivesFeature Request3.70 RC7DeferLowBug in rendering of Bézier patchesTracked on GitHub
0%
Future release Task Description

In version 3.7.0.RC7.msvc10.win64, there is a bug in rendering Bézier patches in which four points (along one edge) are all the same point.

The rendering can be seen here:
http://i.imgur.com/eq2UIXR.png
[Edit: See attachment for the rendering]

As you can see, there is a visible unwanted artifact in the corner of each patch. The two patches shown are essentially the same, except with the 4×4 matrix of vertices transposed (just to demonstrate that simply transposing it didn’t fix it).

Expected rendering is a smooth surface without the artifact.

Below is the code used to render the above example.

#version 3.7;

global_settings { assumed_gamma 1.0 }

camera {

  location <45, 31, -10>
  look_at <40, 21, 200>
  right x*image_width/image_height

}

light_source {

  <660, 300, -525>
  color rgb 1

}

Example 1: First point in each row is the same point
bicubic_patch {
type 1 flatness 0.001
u_steps 4 v_steps 4
<32.2168, -23.78125, 0>, <34.4968, -23.78125, 0>, <35.2168, -23.78125, -0.72>, <35.2168, -23.78125, -3>,
<32.2168, -23.78125, 0>, <34.4968, -22.10256, 0>, <35.2168, -21.57244, -0.72>, <35.2168, -21.57244, -3>,
<32.2168, -23.78125, 0>, <33.9709, -21.55577, 0>, <34.52483, -20.85299, -0.72>, <34.52483, -20.85299, -3>,
<32.2168, -23.78125, 0>, <32.30556, -21.50298, 0>, <32.33359, -20.78352, -0.72>, <32.33359, -20.78352, -3>
rotate 180*x scale 1.4
translate ←5, 0, 0>
pigment { color <1, 0, 0> }
}
Example 2: First row is all the same point
bicubic_patch {

  type 1 flatness 0.001
  u_steps 4 v_steps 4
  <32.2168, -23.78125, 0>, <32.2168, -23.78125, 0>, <32.2168, -23.78125, 0>, <32.2168, -23.78125, 0>,
  <34.4968, -23.78125, 0>, <34.4968, -22.10256, 0>, <33.9709, -21.55577, 0>, <32.30556, -21.50298, 0>,
  <35.2168, -23.78125, -0.72>, <35.2168, -21.57244, -0.72>, <34.52483, -20.85299, -0.72>, <32.33359, -20.78352, -0.72>,
  <35.2168, -23.78125, -3>, <35.2168, -21.57244, -3>, <34.52483, -20.85299, -3>, <32.33359, -20.78352, -3>
  rotate 180*x
  scale 1.4
  pigment { color <1, 1, 0> }

}

282Image formatFeature RequestNot applicableDeferLowUnrendered region should be transparent, not blackTracked on GitHub
0%
Future release Task Description

When rendering only a region of a file, using the command-line options +sc/+sr/+ec/+er, the area of the image that is excluded comes out as black in the final PNG.

Expected behaviour is for it to be transparent.

118Light sourceFeature Request3.70 beta 37aVery LowLowMore efficient handling of fading lightsTracked on GitHub
0%
3.71 release Task Description

Currently, fading light sources are used for lighting and shadow
calculations even when so far away as to no longer have any effect
on the outcome. The proposed solution is to add a new keyword
fade_cutoff_distance which tells povray to ignore the light
source when alluminating a point at larger distance.

A sample implementation is provided in the attached files. These
changes are still based on beta 34 as sources for the current beta
are not yet available, and starting to merge changes to beta 35
only at this time didn’t seem worth the effort. Also, please
disregard, changes in the CVS header comments (I also use
CVS locally for managing source files).

Further considerations regarding this feature:

- For special effects this feature can also be used if the light
source does not actually use fading. On the other hand, cutting
the light at some distances can be considered an extreme form
of fading which may justify the keyword name anyhow.

- Depending on how  FS#46  is implemented, the test for cutoff may
then be needed at another location as well.

- The default value currently is 0 (or *no* cutoff distance). For
#version 3.7 of higher, the default could be chosen automatically
based on the light source intensity and adc_bailout, although it
may then need to be overriden by the user for extreme pigments.

272OtherFeature Request3.70 RC6DeferVery LowMinor change, significant speedup in cubic polynomial s...Tracked on GitHub
0%
3.71 release Task Description

While familiarizing myself with the code, I found some small changes in the solve_cubic function that lead to a significant speedup.

In my experience, “pow” is by far the slowest function in math.h and replacing it with simpler functions usually makes a tremendous impact on the speed (it’s an order of magnitude slower than sqrt/exp/cbrt/log).

solve_cubic has a “pow” function that can be replaced by cbrt (cubic root), which is standard in ISO-C99 and should be available on all systems. Separate benchmarks of solve_cubic function show this change almost doubles the speed and does not lower the accuracy. As solve_cubic is part of the solution of quartic equation, this improves the speed for many primitives. Testing with a scene containing many torus intersection tests (attached below) I still observed almost 10% speedup (Intel, 4 threads, 2 hyperthreaded cores, antialiasing on, 600×600: from 91 to 84 seconds). And this is for a torus, where a lot of time is spent in the solve_quartic and cubic solver is only called once! Similar speedup should be expected for prism, ovus, sor and blob.

I do believe the cubic solver can be done without trigonometry, but that would mean changing the algorithm, introducing new bugs and requiring a lot of testing. However, the trigonometric evaluation can still be simplified (3% speedup in full torus benchmark).

These changes don’t affect the algorithm at all, they are mathematically identical to the existing code, so the changes can be applied immediately. I also included other changes just as suggestions. Every change is commented and marked with [SC 2.2013].

This sadly does not speedup the sturm solver, which uses bisection and regula-falsi and looks very optimized already.

The test scene I used has a lot of torus intersections from various directions (shadow rays, main rays, transmitted rays).

20User interfaceFeature Request3.70 beta 32Very LowVery Lowrender window behaviorTracked on GitHub
0%
Task Description

When changing the behavior of the render window, “Keep above main”, requires restarting the POV editor to take effect. It would be nice either to get a warning to restart, or to get it to work without restarting.

41OtherFeature Request3.70 beta 32Very LowLowimprove command-line parsing error messagesTracked on GitHub
0%
Task Description

POV-Ray 3.6, upon encountering problems when parsing command line and/or .ini file options, would quote the offending option in the error message.

POV-Ray 3.7 currently just reports that there is some problem with the command line, without providing any details. I suggest changing this, as the information may be helpful at times.

138User interfaceFeature Request3.70 beta 37aVery LowLow"Rename" option in File menuTracked on GitHub
0%
Task Description

Would be great if there were a “Rename” option in the editor File menu to rename the current file name. Otherwise, you have to close the file, rename it in file manager, then open the file again, thus loosing the current tab position and undo history for the file.

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