View source for Software:OptiX

{{Short description|Nvidia ray tracing API using CUDA to compute on GPUs}}
{{Infobox software
| name = Nvidia OptiX
| logo = OptiX logo.png
| logo caption = Official logo
| logo size = 200px
| screenshot = 
| caption = 
| developer = [[Company:Nvidia|Nvidia]]
| programming language = [[C (programming language)|C]] / [[C++]]
| genre = [[Ray tracing (graphics)|Ray tracing]]
| license = [[Proprietary software]], free for commercial use
| website = [https://developer.nvidia.com/optix Nvidia OptiX developer site]
| latest_release_version = 8.0
| latest_release_date = {{Start date|2023|08}}
| operating_system = [[Software:Linux|Linux]], [[Software:OS X|OS X]], [[Software:Windows 7|Windows 7]] and later
}}
'''Nvidia OptiX''' ('''OptiX Application Acceleration Engine''') is a [[Ray tracing (graphics)|ray tracing]] [[Application programming interface|API]] that was first developed around 2009.<ref>{{cite web |url=http://highperformancegraphics.org/previous/www_2009/presentations/nvidia-rt.pdf |title=Scheduling in OptiX, the Nvidia ray tracing engine |date=2009-08-15}}</ref> The computations are offloaded to the [[Graphics processing unit|GPU]]s through either the low-level or the high-level [[Application programming interface|API]] introduced with CUDA. CUDA is only available for Nvidia's graphics products. Nvidia OptiX is part of [[Software:Nvidia GameWorks|Nvidia GameWorks]]. OptiX is a high-level, or "to-the-algorithm" API, meaning that it is designed to encapsulate the entire algorithm of which ray tracing is a part, not just the ray tracing itself. This is meant to allow the OptiX engine to execute the larger algorithm with great flexibility without application-side changes.

Commonly, video games use [[Rendering (computer graphics)#rasterisation|rasterization]] rather than ray tracing for their rendering.

According to [[Company:Nvidia|Nvidia]], OptiX is designed to be flexible enough for "procedural definitions and hybrid rendering approaches". Aside from [[Computer graphics|computer graphics]] rendering, OptiX also helps in optical and acoustical design, [[Physics:Radiation|radiation]] and [[Physics:Electromagnetic radiation|electromagnetic]] research,<ref>{{cite book|chapter=Electromagnetic wave propagation in the millimeter wave band using the NVIDIA OptiX GPU ray tracing engine|title=2012 6th European Conference on Antennas and Propagation (EUCAP)|year=2012|publisher=IEEE Xplore|doi=10.1109/EuCAP.2012.6206198|isbn=978-1-4577-0920-3|last1=Felbecker|first1=Robert|last2=Raschkowski|first2=Leszek|last3=Keusgen|first3=Wilhelm|last4=Peter|first4=Michael|pages=488–492|s2cid=45563615}}</ref> [[Artificial intelligence|artificial intelligence]] queries and [[Physics:Collision|collision]] analysis.<ref>{{cite journal|url=https://dl.acm.org/citation.cfm?id=2447976.2447997|title=Magazine Communications of the ACM - GPU ray tracing|author1=Steven G. Parker|author2=Heiko Friedrich|year=2013|publisher=ACM|access-date=2013-08-14|author3=David Luebke|author4=Keith Morley|author5=James Bigler|author6=Jared Hoberock|author7=David McAllister|author8=Austin Robison|author9=Andreas Dietrich|author10=Greg Humphreys|author11=Morgan McGuire|author12=Martin Stich|journal=Communications of the ACM|volume=56|issue=5|pages=93–101|doi=10.1145/2447976.2447997|s2cid=17174671}}</ref>

== Ray tracing with OptiX ==
[[Image:OptiX Julia set.png|thumb|left|A [[Julia set|Julia set]] drawn with NVIDIA OptiX (This is a sample of the [[Software development kit|SDK]].)]]
OptiX works by using user-supplied instructions (in the form of [[Software:CUDA|CUDA]] kernels) regarding what a ray should do in particular circumstances to simulate a complete tracing process.<ref>{{cite journal|url=https://dl.acm.org/citation.cfm?id=1778803|title=OptiX: a general purpose ray tracing engine|author1=Steven G. Parker|author2=Heiko Friedrich|year=2010|publisher=ACM|doi=10.1145/1778765.1778803|access-date=2013-08-14|author3=David Luebke|author4=Keith Morley|author5=James Bigler|author6=Jared Hoberock|author7=David McAllister|author8=Austin Robison|author9=Andreas Dietrich|author10=Greg Humphreys|author11=Morgan McGuire|author12=Martin Stich|journal=ACM Transactions on Graphics |volume=29|issue=4|pages=66:1–66:13}}</ref>

A light ray (or perhaps another kind of ray) might have a different behavior when hitting a particular surface rather than another one, OptiX allows to customize these hit conditions with user-provided programs. These programs are written in CUDA C or directly in PTX code and are linked together when used by the OptiX engine.

In order to use OptiX a [[Software:CUDA|CUDA]]-capable GPU must be available on the system and the CUDA toolkit must be installed.

Using the OptiX engine in a ray tracing application usually involves the following steps:

* Defining programs for ray generation (e.g. rays can be shot in parallel, in a [[Perspective (graphical)|perspective]] fashion or like a [[Gradient|gradient]] field), ray missing (when a ray doesn't intersect any object), an optional exception program (when the ray cannot be shot for some reason), a bounding box program (the program that provides a bounding box intersection test for a given object) and an intersection program.

Several examples for these programs are available with the program's [[Software development kit|SDK]]

<source lang="cpp">
// Sample code using OptiX APIs //

/* Ray generation program */
rtProgramCreateFromPTXFile( *context, path_to_ptx, "pinhole_camera", &ray_gen_program );
rtContextSetRayGenerationProgram( *context, 0, ray_gen_program );

/* Miss program */
rtProgramCreateFromPTXFile( *context, path_to_ptx, "miss", &miss_program );
rtContextSetMissProgram( *context, 0, miss_program );

/* Bounding box and intersection program */
rtProgramCreateFromPTXFile( context, path_to_ptx, "box_bounds", &box_bounding_box_program );
rtGeometrySetBoundingBoxProgram( *box, box_bounding_box_program );
rtProgramCreateFromPTXFile( context, path_to_ptx, "box_intersect", &box_intersection_program );
rtGeometrySetIntersectionProgram( *box, box_intersection_program );
</source>

Bounding box programs are used to define bounding volumes used to accelerate ray tracing process within acceleration structures as kd-trees or bounding volume hierarchies

* Create material any hit and closest hit programs: these two programs determine a ray behavior when encountering its first intersection (closest hit) or a generic intersection (any hit)

<source lang="cpp">
// Sample code using OptiX APIs //

rtProgramCreateFromPTXFile( context, path_to_ptx, "closest_hit_radiance", &closest_hit_program );
rtProgramCreateFromPTXFile( context, path_to_ptx, "any_hit_shadow", &any_hit_program );

/* Associate closest hit and any hit program with a material */
rtMaterialCreate( context, material );
rtMaterialSetClosestHitProgram( *material, 0, closest_hit_program );
rtMaterialSetAnyHitProgram( *material, 1, any_hit_program );
</source>

* Define [[Data buffer|buffer]]s, [[Variable (computer science)|variable]]s that might be used inside the supplied programs. Buffers are memory areas that allow host code (i.e. normal CPU code) to communicate with device code (i.e. the code that gets executed on the [[Graphics processing unit|GPU]]) and vice versa. Variables are OptiX's internal way of communicating and using buffers to transfer data back and forth.
* Define the OptiX hierarchy of geometry objects, groups, selectors and other nodes to generate a tree graph of the entire scene to be rendered

[[File:A sample OptiX© graph tree.png|thumb|A sample graph tree for Nvidia OptiX]]

In order to render a complex scene or trace different paths for any ray OptiX takes advantage of [[General-purpose computing on graphics processing units|GPGPU]] computing by exploiting Nvidia [[Software:CUDA|CUDA]] platform.
Since the process of shooting rays and setting their behavior is highly customizable, OptiX may be used in a variety of other applications aside from ray tracing.

== OptiX Prime ==
Starting from OptiX 3.5.0 a second library called OptiX Prime was added to the bundle which aims to provide a fast low-level [[API]] for ray tracing - building the [[Bounding volume hierarchy|acceleration structure]], traversing the acceleration structure, and [[Möller–Trumbore intersection algorithm|ray-triangle intersection]]. Prime also features a CPU fallback when no compatible GPU is found on the system. Unlike OptiX, Prime is not a programmable API, so lacks support for custom, non-triangle primitives and shading. Being non-programmable, OptiX Prime does not encapsulate the entire algorithm of which ray tracing is a part. Thus, Prime cannot recompile the algorithm for new GPUs, refactor the computation for performance, or use a network appliance like the Quadro VCA, etc.

== Software using OptiX ==
*[[Software:Blender|Blender]] has OptiX support since version 2.81 (7.1 in 2.92) <ref>{{cite web|title=Blender 2.81 Benchmarks On 19 NVIDIA Graphics Cards - RTX OptiX Rendering Performance Is Incredible|publisher=phoronix.com|access-date=2019-11-26|year=2019|url=https://www.phoronix.com/scan.php?page=article&item=blender-281-optix&num=1}}</ref>
* The Blender Add-on [https://remington.pro/software/blender/d-noise/ D-NOISE] uses OptiX binaries for AI-accelerated denoising<ref>{{cite web |title=D-NOISE: Rapid AI Denoising for Blender |url=https://remington.pro/software/blender/d-noise/ |website=Remington Creative |access-date=14 December 2019|date=July 20, 2019 }}</ref>
* [http://furryball.aaa-studio.eu/ FurryBall] - Advanced real-time GPU production quality final frame renderer using raytrace as well as rasterize - based on Nvidia OptiX
* At SIGGRAPH 2011 [[Software:Adobe Systems|Adobe]] showcased OptiX in a technology demo of GPU ray tracing for motion graphics.<ref>{{cite web|title=Adobe showcasing OptiX in a technology demo for ray tracing motion graphics with GPUs|publisher=NVIDIA|access-date=2013-08-14|year=2013|url=https://www.youtube.com/watch?v=3IwgBYBXPOA |archive-url=https://ghostarchive.org/varchive/youtube/20211220/3IwgBYBXPOA |archive-date=2021-12-20 |url-status=live}}{{cbignore}}</ref>
* At SIGGRAPH 2013 OptiX was featured in Pixar's realtime, GPU-based lighting preview tool.
* OptiX has been integrated into the [[Software:Nvidia GameWorks|GameWorks]] developers library along with [[Software:PhysX|PhysX]] and other [[Software:CUDA|CUDA]] powered graphics engines and frameworks.<ref>{{cite web|url=https://gearnuke.com/nvidia-announces-gameworks-program-montreal-2013-supports-steamos/|title=Nvidia announces Gameworks Program at Montreal 2013; supports SteamOS|year=2013|publisher=NVIDIA|access-date=2013-10-29}}</ref>
* [[Software:Adobe After Effects|Adobe After Effects]] CC<ref>{{cite web|url=https://blogs.adobe.com/creativecloud/gpu-changes-for-cuda-and-opengl-in-after-effects-cc-12-1/?segment=dva|title=GPU changes (for CUDA and OpenGL) in After Effects CC (12.1) {{pipe}} After Effects region of interest|access-date=2015-02-22}}</ref>
* [[Software:Daz Studio|Daz Studio]] had OptiX Prime Acceleration since its Iray integration, however support was removed in version 4.12.1.8<ref>{{cite web |title=Daz Studio Changelog |url=http://docs.daz3d.com/doku.php/public/software/dazstudio/4/change_log |website=DAZ 3D |access-date=14 December 2019}}</ref>
* Luxrender 2.5: up to 600% acceleration <ref>{{Cite web|url=https://luxcorerender.org/new-features-in-v2-5/|title = New Features in v2.5 – LuxCoreRender}}</ref>

== See also ==

* [[Software:CUDA|CUDA]]
* [[Nvidia RTX]]

==References==
{{Reflist}}

==External links==
*[https://developer.nvidia.com/optix NVIDIA OptiX Application Acceleration Engine main page]
*[https://raytracing-docs.nvidia.com/ OptiX Programming Guide and OptiX SDK]
*[https://devtalk.nvidia.com/default/board/254/optix/ OptiX support Forum]
*[https://gitlab.com/ingowald/optix7course OptiX 7 Course Tutorial Code]

{{NVIDIA}}

[[Category:Nvidia software]]
[[Category:Proprietary commercial software for Linux]]
[[Category:Ray tracing (graphics)]]

{{Sourceattribution|OptiX}}