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26 | Geometric Primitives | Definite Bug | 3.61 | Very Low | Low | Artifacts rendering a cloth which has two-side textures | Tracked on GitHub | |
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 }
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!
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313 | Radiosity | Definite Bug | 3.70 release | Low | High | radiosity.cpp pov::RadiosityFunction::BeforeTile assert... | Tracked on GitHub | |
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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
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324 | Geometric Primitives | Definite Bug | 3.70 release | Very Low | High | 3.7 mesh2 rendering artifact, regression from 3.6 | Tracked on GitHub | |
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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.
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328 | User interface | Definite Bug | 3.70 release | Very Low | Medium | Ascii char '=' in filenames causes command line parsing... | Tracked on GitHub | |
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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.
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311 | User interface | Possible Bug | 3.70 release | Very Low | Low | Elepsed time error on very long renders | Tracked on GitHub | |
3.71 release |
Task Description
On a very long render, around day 24, the elapsed time display becomes incorrect, showing 4294967272d 4294967272h 4294967272m 4294967272s.
Found on Windows 7 64 bits and reproduced on Windows 7 32 bits. NOT reported on other platforms.
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319 | Texture/Material/Finish | Feature Request | 3.70 release | Very Low | Low | Add interior to #default directive | Tracked on GitHub | |
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Task Description
When working with predefined materials, it would be useful to have something like:
#if (!Use_photons)
#default { interior { caustics 1 } }
#end
#include "my_predefined_materials.inc"
Default medias or IORs could also be useful.
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321 | Other | Definite Bug | 3.70 release | Very Low | Low | bounding threshold inconsistency | Tracked on GitHub | |
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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?
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326 | Other | Definite Bug | 3.70 release | Very Low | Low | restricted setting ignored in 3.7 | Tracked on GitHub | |
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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.
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327 | Parser/SDL | Feature Request | 3.70 release | Very Low | Low | Support for non-ASCII characters in filename strings | Tracked on GitHub | |
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Task Description
pov 3.7 Can not identify the Chinese.I give the texture map filename in chinese,it turns out parse error.
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333 | User interface | Feature Request | 3.70 release | Very Low | Low | Make text in "about" alt+b dialog selectable with the m... | Tracked on GitHub | |
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Task Description
When you press alt+b or access the “about” dialog in the Help menu it displays some text including software version number and list of contributors.
It would be nice to be able to select and copy this text using this mouse. Sometimes in the newsgroup I have to tell people what version of POVray I am using, and typing the version number can be a pain.
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334 | Texture/Material/Finish | Feature Request | 3.70 release | Very Low | Low | HLS colors | Tracked on GitHub | |
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Task Description
It would be nice to be able to specify colors in HLS as well as RGB.
Currently, you can use a macor to convert individual colors. But this does not work in color_maps where you want smooth gradations/interpolations between two or several colors.
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335 | Parser/SDL | Possible Bug | 3.70 release | Very Low | Low | macro works in variable but not in array | Tracked on GitHub | |
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Task Description
This doesn’t work:
#declare pavement_object = array[2] {
object {trash_can_macro() scale 3/4 translate -x * 1/2},
object {potted_plant_macro(_CT_rand2) scale 3/4 scale 3/2 translate -x * 1/2}
}
This does work:
#declare trash_can_object = object {trash_can_macro()}; #declare potted_plant_object = object {potted_plant_macro(_CT_rand2)}; #declare pavement_object = array[2] {
object {trash_can_object scale 3/4 translate -x * 1/2},
object {potted_plant_object scale 3/4 scale 3/2 translate -x * 1/2}
}
Logically, I cannot see a reason for this to be so.
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323 | User interface | Possible Bug | 3.70 release | Very Low | Very Low | Tooltip for render speed status bar has wrong unit | Tracked on GitHub | |
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Task Description
Tooltip popup for render speed always displays as “Pixels per Second” rather than matching status bar. I’ve noticed it in 3 renders so far. Most of my renders are fast enough not to see any other unit besides PPS, but I should be able to reproduce again if necessary.
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44 | Radiosity | Feature Request | All | Very Low | Low | Improve Normals Handling in Radiosity | Tracked on GitHub | |
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”.
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243 | Geometric Primitives | Unimp. Feature/TODO | All | Defer | Low | Sphere sweep behaves wrong when scaled | Tracked on GitHub | |
Future release |
Task Description
The sphere_sweep renders well when specified directly, but when it is scaled, its bounding box is calculated incorrectly, which clips the object so it almost disappears.
The effect is present for all three types of splines.
I’m attaching a test scene and the rendering result. The saving of the object with #declare has no effect, I just wanted to show both transformed and untransformed version.
I don’t think this issue is related to other artifacts occuring with sphere_sweep, as it is obviously an issue of the internal bounding box.
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245 | Other | Feature Request | All | Defer | Low | POVMS message queue can fill up with GB of data for ver... | Tracked on GitHub | |
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).
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242 | Other | Feature Request | All | Defer | Very Low | Algorithm to fix the so-called shadow line artifact | Tracked on GitHub | |
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Task Description
The so-called shadow line artifact (http://wiki.povray.org/content/Knowledgebase:The_Shadow_Line_Artifact) which affects objects with a ‘normal’ statement as well as smooth meshes and heightfields can be really annoying sometimes. Currently the only way to remove it is to make the object shadowless, which isn’t a good solution except in very special cases.
This algorithm could remove the artifact: If the actual normal vector of the object points away from the light source (its dot-product with the light vector is negative) but the perturbed normal points towards it (dot-product positive), then ignore the first shadow-test intersection with the object itself.
There are alternative ways of implementing an equivalent functionality:
- Don’t check the condition (if it’s too difficult to check due to how the code is designed) but always ignore the first intersection with the objects itself. This will work properly with closed surfaces but not with open ones, so it might need to be a feature for the user to turn on with a keyword (similar to eg. ‘double_illuminate’).
- Alternatively, don’t ignore the first intersection, but instead ignore the “opposite side” of the object’s surface (again, possibly only if a keyword has been specified). In other words, if we are rendering the outer side of the object, ignore its inner side when shadow-testing, and vice-versa.
- Perhaps simply add a feature to make surfaces one-sided (similarly to how they can be made so in OpenGL and similar scanline rendering systems). In other words, the inner side of a surface is completely ignored everywhere, making the object virtually invisible from the inside. The advantage of this feature would be that it can have uses other than simply removing the shadow line artifact.
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7 | Radiosity | Unimp. Feature/TODO | 3.70 beta 32 | Low | Medium | Re-implement Radiosity render abort/continue support | Tracked on GitHub | |
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Task Description
For proper render abort/continue support, radiosity cache data must be written to (or read from) disk even if the user does not explicitly opt to have a sample data file written/read. This feature has temporarily been dropped from 3.7 beta and is still pending re-implementation.
To meet high-reproducibility requirements in conjunction with SMP operation, it may be necessary to extend the 3.6 radiosity cache file format.
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42 | Other | Definite Bug | 3.70 beta 32 | Very Low | Medium | command line parameters are not parsed properly on Unix | Tracked on GitHub | |
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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.
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50 | Runtime error | Possible Bug | 3.70 beta 32 | Very Low | Medium | Frequent segfaults with photon scenes | Tracked on GitHub | |
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Task Description
I observe frequent segfaults with POV-Ray 3.7 betas when rendering scenes using photons:
Segfaults are sporadic but frequent (occurring in roughly 50% of all photon renders).
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4 | Subsurface Scattering | Unimp. Feature/TODO | 3.70 beta 32 | Very Low | Low | Integrate Subsurface Scattering with standard lighting ... | Tracked on GitHub | |
Future release |
Task Description
Subsurface Scattering still uses its own rudimentary code to compute illumination from classic light sources; this must be changed to use the standard light source & shadow handling code, to add support for non-trivial light sources (e.g. spotlights, cylindrical lights, area lights), partially-transparent shadowing objects etc.
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6 | Subsurface Scattering | Unimp. Feature/TODO | 3.70 beta 32 | Defer | Low | Integrate Subsurface Scattering with Photons | Tracked on GitHub | |
Future release |
Task Description
Subsurface scattering must be made photon-aware.
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8 | Radiosity | Unimp. Feature/TODO | 3.70 beta 32 | Defer | Low | Improve Radiosity "Cross-Talk" Rejection in Corners | Tracked on GitHub | |
Future release |
Task Description
Near concave edges, radiosity samples may be re-used at a longer distance away from the edge than towards the edge; there is code in place to ensure this, but it only works properly where two surfaces meet roughly rectangularly, while failing near the junction of three surfaces or non-rectangular edges, potentially causing “cross-talk”.
It should be investigated how the algorithm can be improved or replaced to better cope with non-trivial geometry.
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25 | Animation | Definite Bug | 3.70 beta 32 | Defer | Low | Pause sometimes fails when rendering animation | Tracked on GitHub | |
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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.
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27 | Other | Feature Request | 3.70 beta 32 | Very Low | Low | Add texture support to background statement | Tracked on GitHub | |
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.
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28 | Frontend | Feature Request | 3.70 beta 32 | Very Low | Low | #debug message not displayed. | Tracked on GitHub | |
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."
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41 | Other | Feature Request | 3.70 beta 32 | Very Low | Low | improve command-line parsing error messages | Tracked on GitHub | |
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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.
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47 | Preview | Possible Bug | 3.70 beta 32 | Very Low | Low | Render Preveiw window can become disabled | Tracked on GitHub | |
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Task Description
If a render is continued with the +c option and the render had completed, the render preview window will disappear and the show/hide render window button will be grayed. Even after the scene is modified and the command line options have been changed, the show/hide button will still be grayed.
Opening or changing to another scene and rendering will not restore the button, nor will rendering with +d. However, if a trace is started using -d, halted, then continued using +d (or allowed to finish completely with -d and a new one is started using +d), then the preview window is restored.
This behavior is different from 3.6.1, which correctly always showed the preview window (since +d is default) unless -d was specified.
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58 | Parser/SDL | Unimp. Feature/TODO | 3.70 beta 32 | Defer | Low | allow SDL code to detect optional features | Tracked on GitHub | |
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Task Description
Some features are optional in custom builds of POV-Ray (I’m thinking about OpenEXR in particular); it would be nice to have a syntax for an SDL script to check for support of such features, so it may take some fallback action if the feature is not supported.
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20 | User interface | Feature Request | 3.70 beta 32 | Very Low | Very Low | render window behavior | Tracked on GitHub | |
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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.
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85 | Other | Feature Request | Not applicable | Defer | Low | Aspect ratio issues | Tracked on GitHub | |
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).
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96 | Texture/Material/Finish | Feature Request | Not applicable | Very Low | Low | User-defined warps | Tracked on GitHub | |
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) }
}
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248 | Parser/SDL | Feature Request | Not applicable | Very Low | Low | Implement mechanism to compute direction of a spline | Tracked on GitHub | |
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.
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282 | Image format | Feature Request | Not applicable | Defer | Low | Unrendered region should be transparent, not black | Tracked on GitHub | |
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.
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86 | Parser/SDL | Feature Request | Not applicable | Defer | Very Low | Add support for more RNG types | Tracked on GitHub | |
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
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87 | Geometric Primitives | Feature Request | Not applicable | Defer | Very Low | Add new feature: Reference object | Tracked on GitHub | |
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.
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70 | Photons | Unimp. Feature/TODO | 3.70 beta 34 | Low | High | load/save photons should be controlled via command line | Tracked on GitHub | |
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Task Description
Just like radiosity load/save, the photon mapping load/save mechanism should be moved to the frontend and controlled via command-line switch, instead of being SDL-driven in the backend.
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60 | Geometric Primitives | Definite Bug | 3.70 beta 34 | Very Low | Medium | Artifacts using prism in CSG | Tracked on GitHub | |
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.
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75 | Geometric Primitives | Unimp. Feature/TODO | 3.70 beta 34 | Very Low | Medium | Replace POV_MALLOC with std::vector in shape code | Tracked on GitHub | |
Future release |
Task Description
In the files bezier.cpp, fpmetric.cpp, fractal.cpp, hfield.cpp, isosurf.cpp, lathe.cpp, poly.cpp, polygon.cpp, prism.cpp, sor.cpp, and sphsweep.cpp the use of POV_MALLOC can be replaced by std::vector quite easily because the containing class already is a C++ class. As this is a low hanging fruit for continued code cleanup, it should be done sooner rather than later.
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65 | Parser/SDL | Feature Request | 3.70 beta 34 | Very Low | Low | Add support for vectors with functions | Tracked on GitHub | |
Future release |
Task Description
Being able to have functions operate on vectors would be pretty nice to have.
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71 | User interface | Unimp. Feature/TODO | 3.70 beta 34 | Very Low | Low | raise warning when command line option has no effect | Tracked on GitHub | |
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Task Description
Warnings should be raised when a command line option has no effect, for example...
pvengine +am
is legal, but without the number after it, it has no effect.
pvengine +am7
should be an error, and also raises no warnings.
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81 | Geometric Primitives | Definite Bug | 3.62 | Very Low | Medium | sphere_sweep generating artifacts | Tracked on GitHub | |
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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:
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
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98 | Refactoring/Cleanup | Unimp. Feature/TODO | 3.70 beta 36 | Defer | Medium | Refactor Windows UI code for Unicode support | Tracked on GitHub | |
Future release |
Task Description
Windows UI code should be refactored to use _TCHAR throughout instead of char, as well as the corresponding string function macros, to head for Unicode support.
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91 | Texture/Material/Finish | Feature Request | 3.70 beta 36 | Defer | Low | Slope pattern applied to object is not transformed afte... | Tracked on GitHub | |
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
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99 | Refactoring/Cleanup | Unimp. Feature/TODO | 3.70 beta 36 | Defer | Very Low | Refactor engine (front- & back-end) code for Unicode su... | Tracked on GitHub | |
Future release |
Task Description
Front- & Back-end code should be refactored for full Unicode support in scene files and strings.
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79 | Source code | Feature Request | 3.70 beta 35a | Very Low | Low | Full-Featured Test-Scene to check the correctness of po... | Tracked on GitHub | |
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.
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106 | Distribution | Unimp. Feature/TODO | 3.70 beta 37 | Very Low | Low | Update sample scenes and include files for POV-Ray 3.7 ... | Tracked on GitHub | |
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Task Description
Most sample scenes and include files were designed at times when POV-Ray did not to any proper gamma handling, or still used the inferior 3.6 “assumed_gamma” mechanism.
All the scenes and include files should be reviewed, and updated to fit the new 3.7 gamma model.
The primary task will probably be gamma-adjusting literal color values and ambient parameters; I suggest using macros (which ideally should be defined in an include file) to be set according to the #version statement, so the scene/include file could be kept compatible with older versions.
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108 | Parser/SDL | Feature Request | 3.70 beta 37 | Very Low | Low | motion_blur feature similar to Megapov version | Tracked on GitHub | |
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
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115 | Texture/Material/Finish | Feature Request | 3.70 beta 37a | Very Low | Low | More cutaway_textures | Tracked on GitHub | |
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.
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118 | Light source | Feature Request | 3.70 beta 37a | Very Low | Low | More efficient handling of fading lights | Tracked on GitHub | |
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.
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