HOME

TheInfoList



OR:

Software rendering is the process of generating an image from a model by means of computer software. In the context of
computer graphics rendering Rendering or image synthesis is the process of generating a photorealistic or non-photorealistic image from a 2D or 3D model by means of a computer program. The resulting image is referred to as the render. Multiple models can be defined ...
, software rendering refers to a rendering process that is not dependent upon
graphics hardware Graphics hardware is computer hardware that generates computer graphics and allows them to be shown on a display, usually using a graphics card (video card) in combination with a device driver to create the images on the screen. Types Gra ...
ASICs, such as a
graphics card A graphics card (also called a video card, display card, graphics adapter, VGA card/VGA, video adapter, display adapter, or mistakenly GPU) is an expansion card which generates a feed of output images to a display device, such as a computer moni ...
. The rendering takes place entirely in the CPU. Rendering everything with the (general-purpose) CPU has the main advantage that it is not restricted to the (limited) capabilities of graphics hardware, but the disadvantage is that more semiconductors are needed to obtain the same speed. Rendering is used in architecture, simulators, video games, movies and television visual effects and design visualization. Rendering is the last step in an animation process, and gives the final appearance to the models and animation with visual effects such as shading, texture-mapping, shadows,
reflection Reflection or reflexion may refer to: Science and technology * Reflection (physics), a common wave phenomenon ** Specular reflection, reflection from a smooth surface *** Mirror image, a reflection in a mirror or in water ** Signal reflection, in ...
s and motion blur. Rendering can be split into two main categories:
real-time rendering Real-time computer graphics or real-time rendering is the sub-field of computer graphics focused on producing and analyzing images in real time. The term can refer to anything from rendering an application's graphical user interface ( GUI) to ...
(also known as online rendering), and pre-rendering (also called offline rendering). Real-time rendering is used to interactively render a scene, like in 3D computer games, and generally each frame must be rendered in a few milliseconds. Offline rendering is used to create realistic images and movies, where each frame can take hours or days to complete, or for debugging of complex graphics code by programmers.


Real-time software rendering

For real-time rendering the focus is on performance. The earliest texture mapped real-time software renderers for PCs used many tricks to create the illusion of 3D geometry (
true 3D 3D computer graphics, or “3D graphics,” sometimes called CGI, 3D-CGI or three-dimensional computer graphics are graphics that use a three-dimensional representation of geometric data (often Cartesian) that is stored in the computer for th ...
was limited to flat or Gouraud-shaded
polygon In geometry, a polygon () is a plane figure that is described by a finite number of straight line segments connected to form a closed ''polygonal chain'' (or ''polygonal circuit''). The bounded plane region, the bounding circuit, or the two toge ...
s employed mainly in
flight simulator A flight simulator is a device that artificially re-creates aircraft flight and the environment in which it flies, for pilot training, design, or other purposes. It includes replicating the equations that govern how aircraft fly, how they rea ...
s.) ''
Ultima Underworld ''Ultima Underworld: The Stygian Abyss'' is a first-person role-playing video game developed by Blue Sky Productions (later Looking Glass Studios) and published by Origin Systems. Released in March 1992, the game is set in the fantasy world of ...
'', for example, allowed a limited form of looking up and down, slanted floors, and rooms over rooms, but resorted to sprites for all detailed objects. The technology used in these games is currently categorized as 2.5D. One of the first games architecturally similar to modern 3D titles, allowing full
6DoF Six degrees of freedom (6DOF) refers to the six mechanical degrees of freedom of movement of a rigid body in three-dimensional space. Specifically, the body is free to change position as forward/backward (surge), up/down (heave), left/right ...
, was ''
Descent Descent may refer to: As a noun Genealogy and inheritance * Common descent, concept in evolutionary biology * Kinship, one of the major concepts of cultural anthropology **Pedigree chart or family tree ** Ancestry ** Lineal descendant **Heritag ...
'', which featured
3D model In 3D computer graphics, 3D modeling is the process of developing a mathematical coordinate-based representation of any surface of an object (inanimate or living) in three dimensions via specialized software by manipulating edges, vertices, an ...
s entirely made from bitmap textured triangular polygons.
Voxel In 3D computer graphics, a voxel represents a value on a regular grid in three-dimensional space. As with pixels in a 2D bitmap, voxels themselves do not typically have their position (i.e. coordinates) explicitly encoded with their values. Ins ...
-based graphics also gained popularity for fast and relatively detailed terrain rendering, as in ''
Delta Force The 1st Special Forces Operational Detachment–Delta (1st SFOD-D), referred to variously as Delta Force, Combat Applications Group (CAG), Army Compartmented Elements (ACE), "The Unit", or within Joint Special Operations Command (JSOC), Task Fo ...
'', but popular
fixed-function Fixed-function is a term canonically used to contrast 3D graphics APIs and earlier GPUs designed prior to the advent of shader-based 3D graphics APIs and GPU architectures. History Historically fixed-function APIs consisted of a set of function ...
hardware eventually made its use impossible. '' Quake'' features an efficient software renderer by
Michael Abrash Michael Abrash is a programmer and technical writer specializing in code optimization and 80x86 assembly language. He wrote the 1990 book ''Zen of Assembly Language Volume 1: Knowledge'' and a monthly column in '' Dr. Dobb's Journal'' in the ea ...
and
John Carmack John D. Carmack II (born August 20, 1970) is an American computer programmer and video game developer. He co-founded the video game company id Software and was the lead programmer of its 1990s games ''Commander Keen'', ''Wolfenstein 3D'', ''Doo ...
. With its popularity, ''Quake'' and other polygonal 3D games of that time helped the sales of
graphics cards A graphics card (also called a video card, display card, graphics adapter, VGA card/VGA, video adapter, display adapter, or mistakenly GPU) is an expansion card which generates a feed of output images to a display device, such as a computer moni ...
, and more games started using hardware
API An application programming interface (API) is a way for two or more computer programs to communicate with each other. It is a type of software interface, offering a service to other pieces of software. A document or standard that describes how ...
s like
DirectX Microsoft DirectX is a collection of application programming interfaces (APIs) for handling tasks related to multimedia, especially game programming and video, on Microsoft platforms. Originally, the names of these APIs all began with "Direct", ...
and
OpenGL OpenGL (Open Graphics Library) is a cross-language, cross-platform application programming interface (API) for rendering 2D and 3D vector graphics. The API is typically used to interact with a graphics processing unit (GPU), to achieve hardwa ...
. Though software rendering fell off as a primary rendering technology, many games well into the 2000s still had a software renderer as a fallback, ''
Unreal Unreal may refer to: Books and TV * ''Unreal'' (short story collection), a 1985 book of short stories by Paul Jennings * ''Unreal'' (TV series), a 2015 television drama series on Lifetime Computing and games * ''Unreal'' (video game series), ...
'' and ''
Unreal Tournament ''Unreal Tournament'' is a first-person arena shooter video game developed by Epic Games and Digital Extremes. The second installment in the ''Unreal'' series, it was first published by GT Interactive in 1999 for Microsoft Windows, and later r ...
'' for instance, feature software renderers able to produce enjoyable quality and performance on CPUs of that period. One of the last AAA games without a hardware renderer was '' Outcast'', which featured advanced voxel technology but also
texture filtering In computer graphics, texture filtering or texture smoothing is the method used to determine the texture color for a texture mapped pixel, using the colors of nearby texels (pixels of the texture). There are two main categories of texture filtering ...
and
bump mapping Bump mapping is a texture mapping technique in computer graphics for simulating bumps and wrinkles on the surface of an object. This is achieved by perturbing the surface normals of the object and using the perturbed normal during lighting cal ...
as found on graphics hardware. In the
video game console A video game console is an electronic device that Input/output, outputs a video signal or image to display a video game that can be played with a game controller. These may be home video game console, home consoles, which are generally placed i ...
and
arcade game An arcade game or coin-op game is a coin-operated entertainment machine typically installed in public businesses such as restaurants, bars and amusement arcades. Most arcade games are presented as primarily games of skill and include arcade v ...
markets, the evolution of 3D was more abrupt, as they had always relied heavily on single-purpose chipsets. 16 bit consoles gained RISC accelerator cartridges in games such as '' StarFox'' and ''
Virtua Racing ''Virtua Racing'', or ''V.R.'' for short, is a Formula One racing video game developed by Sega AM2 and released for arcades in 1992. ''Virtua Racing'' was initially a proof-of-concept application for exercising a new 3D graphics platform under ...
'' which implemented software rendering through tailored instruction sets. The
Jaguar The jaguar (''Panthera onca'') is a large cat species and the only living member of the genus '' Panthera'' native to the Americas. With a body length of up to and a weight of up to , it is the largest cat species in the Americas and the th ...
and 3DO were the first consoles to ship with 3D hardware, but it wasn't until the
PlayStation is a video gaming brand that consists of five home video game consoles, two handhelds, a media center, and a smartphone, as well as an online service and multiple magazines. The brand is produced by Sony Interactive Entertainment, a divisi ...
that such features came to be used in most games. Games for children and casual gamers (who use outdated systems or systems primarily meant for office applications) during the late 1990s to early 2000s typically used a software renderer as a fallback. For example, '' Toy Story 2: Buzz Lightyear to the Rescue'' has a choice of selecting either hardware or software rendering before playing the game, while others like ''
Half-Life Half-life (symbol ) is the time required for a quantity (of substance) to reduce to half of its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay or how long stable ato ...
'' default to software mode and can be adjusted to use OpenGL or DirectX in the Options menu. Some 3D modeling software also features software renderers for visualization. And finally the
emulation Emulation may refer to: *Emulation (computing), imitation of behavior of a computer or other electronic system with the help of another type of system :*Video game console emulator, software which emulates video game consoles *Gaussian process em ...
and
verification Verify or verification may refer to: General * Verification and validation, in engineering or quality management systems, is the act of reviewing, inspecting or testing, in order to establish and document that a product, service or system meets ...
of hardware also requires a software renderer. An example of the latter is the
Direct3D Direct3D is a graphics application programming interface (API) for Microsoft Windows. Part of DirectX, Direct3D is used to render three-dimensional graphics in applications where performance is important, such as games. Direct3D uses hardware a ...
reference rasterizer. But even for high-end graphics, the 'art' of software rendering hasn't completely died out. While early graphics cards were much faster than software renderers and originally had better quality and more features, it restricted the developer to 'fixed-function' pixel processing. Quickly there came a need for diversification of the looks of games. Software rendering has no restrictions because an arbitrary program is executed. So graphics cards reintroduced this programmability, by executing small programs per
vertex Vertex, vertices or vertexes may refer to: Science and technology Mathematics and computer science *Vertex (geometry), a point where two or more curves, lines, or edges meet * Vertex (computer graphics), a data structure that describes the positio ...
and per
pixel In digital imaging, a pixel (abbreviated px), pel, or picture element is the smallest addressable element in a raster image, or the smallest point in an all points addressable display device. In most digital display devices, pixels are the smal ...
/ fragment, also known as
shaders In computer graphics, a shader is a computer program that calculates the appropriate levels of light, darkness, and color during the Rendering (computer graphics), rendering of a 3D scene - a process known as ''shading''. Shaders have evolved ...
. Shader languages, such as
High Level Shader Language The High-Level Shader Language or High-Level Shading Language (HLSL) is a proprietary shading language developed by Microsoft for the Direct3D 9 API to augment the shader assembly language, and went on to become the required shading language ...
(HLSL) for DirectX or the
OpenGL Shading Language OpenGL Shading Language (GLSL) is a high-level shading language with a syntax based on the C programming language. It was created by the OpenGL ARB (OpenGL Architecture Review Board) to give developers more direct control of the graphics pipelin ...
(GLSL), are C-like programming languages for shaders and start to show some resemblance with (arbitrary function) software rendering. Since the adoption of graphics hardware as the primary means for real-time rendering, CPU performance has grown steadily as ever. This allowed for new software rendering technologies to emerge. Although largely overshadowed by the performance of hardware rendering, some modern real-time software renderers manage to combine a broad feature set and reasonable performance (for a software renderer), by making use of specialized
dynamic compilation Dynamic compilation is a process used by some programming language implementations to gain performance during program execution. Although the technique originated in Smalltalk,Peter L. Deutsch and Alan Schiffman. "Efficient Implementation of the ...
and advanced instruction set extensions like SSE. Although nowadays the dominance of hardware rendering over software rendering is undisputed because of unparalleled performance, features, and continuing innovation, some believe that CPUs and
GPU A graphics processing unit (GPU) is a specialized electronic circuit designed to manipulate and alter memory to accelerate the creation of images in a frame buffer intended for output to a display device. GPUs are used in embedded systems, mobi ...
s will converge one way or another and the line between software and hardware rendering will fade.


Software fallback

For various reasons such as hardware failure, broken drivers, emulation, quality assurance, software programming, hardware design, and hardware limitations, it is sometimes useful to let the CPU assume some or all functions in a graphics pipeline. As a result, there are a number of general-purpose software packages capable of replacing or augmenting an existing hardware graphical accelerator, including: * RAD Game Tools' Pixomatic, sold as middleware intended for static linking inside D3D 7–9 client software. * SwiftShader, a library sold as middleware intended for bundling with D3D9 & OpenGL ES 2 client software. * The swrast, softpipe, & LLVMpipe renderers inside
Mesa A mesa is an isolated, flat-topped elevation, ridge or hill, which is bounded from all sides by steep escarpments and stands distinctly above a surrounding plain. Mesas characteristically consist of flat-lying soft sedimentary rocks capped by ...
work as a shim at the system level to emulate an OpenGL 1.4–3.2 hardware device. *
WARP Warp, warped or warping may refer to: Arts and entertainment Books and comics * WaRP Graphics, an alternative comics publisher * ''Warp'' (First Comics), comic book series published by First Comics based on the play ''Warp!'' * Warp (comics), a ...
, provided since Windows Vista by Microsoft, which works at the system level to provide fast D3D 9.1 and above emulation. This is in addition to the extremely slow software-based reference rasterizer Microsoft has always provided to developers. * The Apple software renderer in CGL, provided in Mac OS X by Apple, which works at the system level to provide fast OpenGL 1.1–4.1 emulation.


Pre-rendering

Contrary to real-time rendering, performance is only of second priority with pre-rendering. It is used mainly in the film industry to create high-quality renderings of lifelike scenes. Many
special effects Special effects (often abbreviated as SFX, F/X or simply FX) are illusions or visual tricks used in the theatre, film, television, video game, amusement park and simulator industries to simulate the imagined events in a story or virtual wor ...
in today's movies are entirely or partially created by computer graphics. For example, the character of
Gollum Gollum is a fictional Tolkien's monsters, character in J. R. R. Tolkien's Middle-earth legendarium. He was introduced in the 1937 Fantasy (genre), fantasy novel ''The Hobbit'', and became important in its sequel, ''The Lord of the Rings''. Gol ...
in the
Peter Jackson Sir Peter Robert Jackson (born 31 October 1961) is a New Zealand film director, screenwriter and producer. He is best known as the director, writer and producer of the ''Lord of the Rings'' trilogy (2001–2003) and the ''Hobbit'' trilogy ( ...
''
The Lord of the Rings ''The Lord of the Rings'' is an epic high-fantasy novel by English author and scholar J. R. R. Tolkien. Set in Middle-earth, intended to be Earth at some time in the distant past, the story began as a sequel to Tolkien's 1937 children's boo ...
'' films is completely
computer-generated imagery Computer-generated imagery (CGI) is the use of computer graphics to create or contribute to images in art, printed media, video games, simulators, and visual effects in films, television programs, shorts, commercials, and videos. The images may ...
(CGI). Also for
animation Animation is a method by which image, still figures are manipulated to appear as Motion picture, moving images. In traditional animation, images are drawn or painted by hand on transparent cel, celluloid sheets to be photographed and exhibited ...
movies, CGI is gaining popularity. Most notably
Pixar Pixar Animation Studios (commonly known as Pixar () and stylized as P I X A R) is an American computer animation studio known for its critically and commercially successful computer animated feature films. It is based in Emeryville, Californi ...
has produced a series of movies such as ''
Toy Story ''Toy Story'' is a 1995 American computer-animated comedy film directed by John Lasseter (in his feature directorial debut), produced by Pixar Animation Studios and released by Walt Disney Pictures. The first installment in the '' Toy Story ...
'' and ''
Finding Nemo ''Finding Nemo'' is a 2003 American computer-animated comedy-drama adventure film produced by Pixar Animation Studios and released by Walt Disney Pictures. Directed by Andrew Stanton with co-direction by Lee Unkrich, the screenplay was writ ...
'', and the Blender Foundation the world's first open movie '' Elephants Dream''. Because of the need for very high-quality and diversity of effects, offline rendering requires a lot of flexibility. Even though commercial real-time graphics hardware is becoming higher in quality and more programmable by the day, most
photorealistic Photorealism is a genre of art that encompasses painting, drawing and other graphic media, in which an artist studies a photograph and then attempts to reproduce the image as realistically as possible in another medium. Although the term can be ...
CGI still requires software rendering. Pixar's
RenderMan The name RenderMan can cause confusion because it has been used to refer to different things developed by Pixar Animation Studios: * RenderMan Interface Specification (RISpec), an open API (technical specification) developed by Pixar for a standard ...
, for example, allows shaders of unlimited length and complexity, demanding a general-purpose processor. Techniques for high realism like raytracing and
global illumination Global illumination (GI), or indirect illumination, is a group of algorithms used in 3D computer graphics that are meant to add more realistic lighting to 3D scenes. Such algorithms take into account not only the light that comes directly from ...
are also inherently unsuited for hardware implementation and in most cases are realized purely in software.


See also

*
3D computer graphics 3D computer graphics, or “3D graphics,” sometimes called CGI, 3D-CGI or three-dimensional computer graphics are graphics that use a three-dimensional representation of geometric data (often Cartesian) that is stored in the computer for th ...
*
Z-buffering A depth buffer, also known as a z-buffer, is a type of data buffer used in computer graphics to represent depth information of objects in 3D space from a particular perspective. Depth buffers are an aid to rendering a scene to ensure that the ...


References

{{computer graphics 3D rendering