Editing POV-Ray

{{Short description|Text-based ray-tracing program}}
{{Infobox software
| name = POV-Ray
| logo = Povray logo sphere.png
| logo size = 140px
| screenshot = 
| author = David Kirk Buck, Aaron A. Collins, Alexander Enzmann
| developer = The POV-Team
| released = {{Nowrap|{{Start date and age|1991|7|29}}<ref name="History">{{Cite web |url=http://www.povray.org/documentation/view/3.6.1/10/ |title=POV-Ray: Documentation: 1.1.5.3 A Historic 'Version History' |website=povray.org |access-date=2018-12-19}}</ref><ref name="POV-Ray 25">{{Cite web |url=http://www.povray.org/news/index.php#323 |title=POV-Ray: News |website=povray.org |access-date=2018-12-19}}</ref>}}
| latest release version = {{wikidata|property|edit|reference|P348}}
| latest release date = {{wikidata|qualifier|P348|P577}}
| latest_preview_version = <!-- Used by Template:Latest preview software release/POV-Ray -->
| programming language = [[C++]]
| operating_system = [[Cross-platform]]
| genre = [[Ray tracing (graphics)|Ray tracer]]
| license = [[GNU Affero General Public License|AGPL-3.0-or-later]]<ref>{{cite web|url=http://www.povray.org/povlegal.html |title=POV-Ray License |publisher=povray.org |access-date=2014-05-05}}</ref>
| website = {{url|https://www.povray.org/|povray.org}}
}}

The '''Persistence of Vision Ray Tracer''', most commonly acronymed as '''POV-Ray''', is a [[Cross-platform software|cross-platform]] [[ray tracing (graphics)|ray-tracing]] program that generates images from a text-based scene description. It was originally based on DKBTrace, written by David Kirk Buck and Aaron A. Collins for [[Amiga]] computers. There are also influences from the earlier Polyray<ref>{{cite web|url=http://paulbourke.net/dataformats/polyray/ |title=Polyray v1.7 |publisher=Alexander R. Enzmann |access-date=2016-07-05}}</ref> raytracer because of contributions from its author, Alexander Enzmann. POV-Ray is [[free and open-source software]], with the [[source code]] available under the [[GNU Affero General Public License|AGPL-3.0-or-later]] license.

==History==
[[File:Vase on a pedestal, rendered with DKBTrace 2.12.png|thumb|A vase on a pedestal rendered with DKBTrace 2.12]]
Sometime in the 1980s, David Kirk Buck downloaded the [[source code]] for a [[Unix]] ray tracer to his [[Amiga]]. He experimented with it for a while and eventually decided to write his own ray tracer named DKBTrace after his initials. He posted it to the "You Can Call Me Ray" [[bulletin board system]] (BBS) in Chicago, thinking others might be interested in it. In 1987, Aaron A. Collins downloaded DKBTrace and began working on an [[x86]] port of it. He and David Buck collaborated to add several more features.  POV also had/has similarities with (and borrows from) Rayshade, another BBS era raytracer, including the short but good [[Rayshade]] book.

When the program proved to be more popular than anticipated, they could not keep up with demand for more features. Thus, in July 1991, David turned over the project to a team of programmers working in the "GraphDev" [[Online forum|forum]] on [[CompuServe]]. At the same time, David felt that it was inappropriate to use his initials on a program he no longer maintained.  The name "STAR-Light" (Software Taskforce on Animation and Rendering) was initially used, but eventually the name became "PV-Ray", and then ultimately "POV-Ray" (Persistence of Vision Ray Tracer),<ref name="POV-Ray 25"/> a name inspired by [[Salvador Dalí|Dalí]]'s painting, ''[[The Persistence of Memory]]''.<ref>{{cite web|url=http://www.povray.org/documentation/view/3.6.0/7/ |title=Documentation: 1.1.5 The Early History of |publisher=POV-Ray |access-date=2014-05-05}}</ref><ref name="flossweekly2008"/>

Features of the application, and a summary of its history, are discussed in a February 2008 interview with David Kirk Buck and Chris Cason on episode 24 of [[FLOSS Weekly]].<ref name="flossweekly2008">{{cite web|url=http://twit.tv/floss24 |title=The TWiT Netcast Network with Leo Laporte |publisher=Twit.tv |access-date=2014-05-05 |date=2008-02-07}}</ref>

==Features==
[[Image:Glasses 800 edit.png|thumb|Glass scene rendered by POV-Ray demonstrating [[Radiosity (computer graphics)|radiosity]], [[photon mapping]], [[focal blur]], and other photorealistic capabilities (image created by [[Gilles Tran]])]]

POV-Ray has matured substantially since it was created. Recent versions of the software include the following features:

* a [[Turing-completeness|Turing-complete]] scene description language (SDL) that supports macros and loops<ref>[http://paulbourke.net/geometry/supershape/ Paul Bourke: Supershape in 3D] are examples of POV-Ray images made with very short code</ref>
* a library of ready-made scenes, textures, and objects
* support for a number of [[geometric primitive]]s and [[constructive solid geometry]]
* several kinds of [[light source]]s
* atmospheric effects such as [[fog]] and ''media'' ([[smoke]], [[clouds]])
* [[Reflection (physics)|reflection]]s, [[refraction]]s, and light [[caustic (optics)|caustics]] using [[photon mapping]]
* surface patterns such as [[wrinkle]]s, bumps, and [[Capillary wave|ripples]], for use in [[procedural texture]]s and [[bump mapping]]
* [[Radiosity (computer graphics)|radiosity]]
* support for [[Texture (computer graphics)|textures]] and rendered output in many image formats, including [[Truevision Targa file format|TGA]], [[Portable Network Graphics|PNG]], and [[JPEG]], among others
* extensive [[user documentation]]
* support for custom output resolutions<ref>{{Cite web |title=POV-Ray: Documentation: 2.1.2.2 General Output Options |url=https://www.povray.org/documentation/view/3.6.0/217/ |access-date=2023-09-08 |website=www.povray.org}}</ref> (This includes extreme resolutions such as [[16K resolution|16K]])
* two types of [[Supersampling|SSAA]]<ref name=":0">{{Cite web |title=POV-Ray: Documentation: 2.1.2.8 Tracing Options |url=http://www.povray.org/documentation/view/3.6.2/223/ |access-date=2023-09-08 |website=www.povray.org}}</ref> Type 1 is an adaptive, non-recursive, super-sampling method. It is ''adaptive'' because not every pixel is super-sampled. Type 2 is an adaptive and recursive super-sampling method. It is ''recursive'' because the pixel is sub-divided and sub-sub-divided recursively. The ''adaptive'' nature of type 2 is the variable depth of recursion.<ref name=":0" />

One of POV-Ray's main attractions is its large collection of third-party-made assets and tools. A large number of tools, textures, models, scenes, and tutorials can be found on the web. It is also a useful reference for those wanting to learn how [[ray tracing (graphics)|ray tracing]] and related 3D geometry and computer graphics algorithms work.

===Current version===
The current official version of POV-Ray is 3.7. This version introduces:

* support for [[symmetric multiprocessing]] (SMP), to allow the renderer to take advantage of [[Multiprocessing|multiple processors]]
* support for [[high-dynamic-range imaging]] (HDRI), including the [[OpenEXR]] and [[Radiance (software)|radiance]] file formats
* improved [[Bounding volume|bounding]] using [[Binary space partitioning|BSP]] trees

Some of the main introduced features of the previous release (3.6) are:

* extending [[UV mapping]] to more primitives
* adding 16- and 32-bit integer data to a density file
* improving [[64-bit computing|64-bit]] [[computer compatibility|compatibility]]

In July 2006, [[Intel Corporation]] started using the [[beta version]] of 3.7 to demonstrate their new [[dual-core]] [[Conroe (microprocessor)|Conroe processor]] due to the efficiency of the SMP (symmetric multiprocessing) implementation.

===Primitives===
[[File:Venn 0000 0001 0001 0110.png|thumb|Rendering of the [[Venn diagram]] of four spheres created with [[constructive solid geometry]], or CSG. The source is [[commons:File:Venn 0000 0001 0001 0110.png#POV-Ray source|on the description page]] of the image.]]
[[Image:PNG transparency demonstration 1.png|thumb|Some colored [[dice]] rendered in POV-Ray. [[Constructive solid geometry|CSG]], [[refraction]] and [[focal blur]] are demonstrated.]]
POV-Ray, in addition to standard [[3d geometry|3D geometric]] shapes like [[torus|tori]], [[sphere]]s, and [[heightfield]]s, supports mathematically defined ''[[Primitives (computer graphics)|primitives]]'' such as the [[isosurface]] (a finite approximation of an arbitrary function), the [[polynomial]] primitive (an [[Infinity|infinite]] object defined by a [[Degree of a polynomial|15th order or lower polynomial]]), the [[julia set|julia fractal]] (a 3-dimensional slice of a [[Four-dimensional space|4-dimensional]] fractal), the [[superellipse|superquadratic ellipsoid]] (an intermediate between a sphere and a cube), and the [[parametric feature based modeler|parametric]] primitive (using equations that represent its surface, rather than its interior).

POV-Ray internally represents objects using their mathematical definitions; all POV-Ray primitive objects can be described by [[mathematical functions]]. This is different from many computer programs that include 3D models, which typically use [[triangle]] [[polygon mesh|mesh]]es to compose all the objects in a scene.

This fact provides POV-Ray with several advantages and disadvantages over other rendering and modeling systems; POV-Ray primitives are more accurate than their polygonal counterparts: objects that can be described in terms of spheres, planar surfaces, cylinders, tori, and the like, are perfectly smooth and mathematically accurate in POV-Ray renderings, whereas polygonal ''artifacts'' may be visible in mesh-based modeling software. POV-Ray primitives are also simpler to define than most of their polygonal counterparts, e.g., in POV-Ray, a [[sphere]] is described simply by its center and radius; in a mesh-based environment, a sphere must be described by a multitude of small connected polygons (usually [[UV sphere|quads]] or [[Icosphere|triangles]]).

On the other hand, script-based primitive modeling is not always a practical method to create certain objects, such as realistic characters or complex man-made artifacts like cars. Those objects can be created first in mesh-based modeling applications such as [[Wings 3D]] and [[Blender (software)|Blender]], and then they can be converted to POV-Ray's own mesh format.

===Examples of the scene description language===
The following is an example of the scene description language used by POV-Ray to describe a scene to render. It demonstrates the use of a background colour, camera, lights, a simple box shape having a surface normal and finish, and the transforming effects of rotation.

[[Image:I example povray scene rendering.png|thumb|right|POV-Ray image output based on the script]]

<syntaxhighlight lang="pov">
 #version 3.6;
// Includes a separate file defining a number of common colours
 #include "colors.inc"
 global_settings { assumed_gamma 1.0 }

// Sets a background colour for the image (dark grey)
 background   { color rgb <0.25, 0.25, 0.25> }

// Places a camera
// direction: Sets, among other things, the field of view of the camera
// right: Sets the aspect ratio of the image
// look_at: Tells the camera where to look
 camera       { location  <0.0, 0.5, -4.0>
                direction 1.5*z
                right     x*image_width/image_height
                look_at   <0.0, 0.0, 0.0> }

// Places a light source
// color: Sets the color of the light source (white)
// translate: Moves the light source to a desired location
 light_source { <0, 0, 0>
                color rgb <1, 1, 1>
                translate <-5, 5, -5> }
// Places another light source
// color: Sets the color of the light source (dark grey)
// translate: Moves the light source to a desired location
 light_source { <0, 0, 0>
                color rgb <0.25, 0.25, 0.25>
                translate <6, -6, -6> }

// Sets a box
// pigment: Sets a color for the box ("Red" as defined in "colors.inc")
// finish: Sets how the surface of the box reflects light
// normal: Sets a bumpiness for the box using the "agate" in-built model
// rotate: Rotates the box
 box          { <-0.5, -0.5, -0.5>,
                <0.5, 0.5, 0.5>
                texture { pigment { color Red }
                          finish  { specular 0.6 }
                          normal  { agate 0.25 scale 1/2 }
                        }
                rotate <45,46,47> }
</syntaxhighlight>

The following script fragment shows the use of variable declaration, assignment, comparison and the while loop construct:

[[Image:I example povray scene rendering2.png|thumb|right|POV-Ray image output based on the script]]

<syntaxhighlight lang="pov">
 #declare the_angle = 0;

 #while (the_angle < 360)
 	box {   <-0.5, -0.5, -0.5>
 		<0.5, 0.5, 0.5>
                texture { pigment { color Red }
                          finish  { specular 0.6 }
                          normal  { agate 0.25 scale 1/2 } }
 		rotate the_angle }
 	#declare the_angle = the_angle + 45;
 #end
</syntaxhighlight>

==Modeling==
The POV-Ray program itself does not include a [[3D modeling|modeling]] feature; it is essentially a pure renderer with a sophisticated model description language. To accompany this feature set, third parties have developed a large variety of modeling software, some specialized for POV-Ray, others supporting import and export of its data structures, including the free and open-source 3D creation suite [[Blender (software)|Blender]].<ref>[https://en.blender.org/index.php/Extensions:2.6/Py/Scripts/Render/POV-Ray Blender]</ref>

A number of additional POV-Ray compatible modelers are linked from [http://www.povray.org/resources/links/3D_Programs/Modelling_Programs/ Povray.org: Modelling Programs].

In 2007, POV-Ray acquired the rights to [http://www.stmuc.com/moray/medown.html Moray] {{Webarchive|url=https://web.archive.org/web/20200428230409/http://www.stmuc.com/moray/medown.html |date=2020-04-28 }},<ref>{{cite web|url=http://www.povray.org/news/moray-announcement.php |title=News: Moray Announcement |publisher=POV-Ray |date=2007-02-01 |access-date=2014-05-05}}</ref> an interactive 3-D modeling program long used with POV-Ray. However, as of December 2016, Moray development is stalled.<ref>{{cite web|url=https://github.com/POV-Ray/povray#3d-modeller |title=POV-Ray/povray: The persistence of Vision Raytracer|publisher=POV-Ray |date=2013-09-06 |access-date=2022-08-05}}</ref>

==Software==
===Development and maintenance===
Official modifications to the POV-Ray source tree are done and/or approved by the POV-Team. Most patch submission and/or bug reporting is done in the POV-Ray newsgroups on the [nntp://news.povray.org/ news.povray.org] [[Usenet|news]] server (with a [[Web interface]] [http://news.povray.org/groups/ also available]). Since POV-Ray's source is available there are unofficial [[Fork (software)|fork]]s and patched versions of POV-Ray available from third parties; however, these are not officially supported by the POV-Team.

Official POV-Ray versions currently do not support [[shader]] plug-ins.<ref>for such an implementation, see e.g., http://www.aetec.ee/fv/vkhomep.nsf/pages/povman2 {{Webarchive|url=https://web.archive.org/web/20070207122812/http://www.aetec.ee/fv/vkhomep.nsf/pages/povman2 |date=2007-02-07 }}</ref> Some features, like [[Radiosity (computer graphics)|radiosity]] and [[spline (mathematics)|spline]]s are still in development and may be subject to syntactical change.

===Platform support===
POV-Ray 3.6 is distributed in compiled format for [[Mac (computer)|Mac]], [[Microsoft Windows|Windows]] and [[Linux]].
Support for [[Apple–Intel architecture|Intel Mac]]s is not available in the [[Mac (computer)|Mac]] version, but since [[Mac OS X]] is a version of [[Unix]] the Linux version can be [[Compiler|compiled]] on it.

The 3.7 versions with [[Symmetric multiprocessing|SMP]] support are officially supported for Windows and Linux. Unofficial [[Mac (computer)|Mac]] versions for v3.7 can be found.<ref>[http://megapov.inetart.net/povrayunofficial_mac/index.html povrayunofficial_mac] on megapov.inetart.net</ref>

POV-Ray can be [[Source port|ported]] to any platform which has a compatible [[C++]] compiler.

===Licensing===
Originally, POV-Ray was distributed under its own ''POV-Ray License''; namely, the POV-Ray 3.6 Distribution License<ref>{{cite web|url=http://www.povray.org/distribution-license-3.6.html |title=POV-Ray 3.6 Distribution License |publisher=povray.org |access-date=2016-12-12}}</ref> and the POV-Ray 3.6 Source License,<ref>{{cite web|url=http://www.povray.org/source-license-3.6.html |title=POV-Ray 3.6 Source License |publisher=povray.org |access-date=2016-12-12}}</ref> which permitted free distribution of the program source code and binaries, while restricting commercial distribution and the creation of derivative works other than fully functional versions of POV-Ray.

Although the [[source code]] of older versions is available for modification, due to the above 3.6 and prior license restrictions, it was not [[Open-source software|open source]] or [[free software]] according to the [[Open Source Initiative|OSI]] or the [[Free Software Foundation|FSF]] definition of the term. This was a problem as [[source code]] exchange with the greater [[Free and open-source software|FOSS]] ecosystem was impossible due to [[license incompatibility]] with [[copyleft license]]s.

One of the reasons that POV-Ray was not originally licensed under the free software [[GNU General Public License]] (GPL), or other open source licenses, is that POV-Ray was developed before the GPL-style licenses became widely used; the developers wrote their own license for the release of POV-Ray, and contributors to the software worked under the assumption their contributions would be licensed under the POV-Ray 3.6 Licenses.

In 2013, with version 3.7, POV-Ray was relicensed under the [[GNU Affero General Public License]] version 3 (or later).<ref>{{cite web
| url=http://www.povray.org/download/
| title=Download POV-Ray 3.7.0
| last=Cason |first=Chris
| date=8 November 2013
| quote=Starting with version 3.7, POV-Ray is released under the AGPL3 (or later) license and thus is Free Software according to the FSF definition.  [...] Full source code is available, allowing users to build their own versions and for developers to incorporate portions or all of the POV-Ray source into their own software provided it is distributed under a compatible license (for example, the AGPL3 or – at their option – any later version).
| access-date=11 November 2013}}</ref> Thus POV-Ray is since then [[free software]] according to the [[Free Software Foundation|FSF]] definition and also [[open source software]] according to the [[Open Source Definition]].

==See also==
{{Portal|Amiga|Free and open-source software}}
{{commons|POV-Ray}}
* [[Blender (software)|Blender]] – a free and open-source software program for 3D modeling, animation, and rendering
* [[Kerkythea]] – a freeware ray-tracing program with enhanced [[Sketchup]] compatibility
* [[Sunflow]] – an open-source rendering system for photo-realistic image synthesis, written in Java

==References==
{{Reflist|30em}}

==External links==
{{commons category|POV-Ray}}
* {{Official website|www.povray.org}}

{{3D software}}

{{DEFAULTSORT:Pov-Ray}}
[[Category:3D graphics software]]
[[Category:Amiga raytracers]]
[[Category:Articles with example code]]
[[Category:Cross-platform software]]
[[Category:Domain-specific programming languages]]
[[Category:Free 3D graphics software]]
[[Category:Free graphics software]]
[[Category:Free software programmed in C++]]
[[Category:Global illumination software]]
[[Category:Rendering systems]]
[[Category:Software using the GNU Affero General Public License]]