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Renderman Shading Language (abbreviated RSL) is a component of the RenderMan Interface Specification, and is used to define shaders. The language syntax is C-like.
A shader written in RSL can be used without changes on any RenderMan-compliant renderer, such as Pixar's PhotoRealistic RenderMan, DNA Research's 3Delight, Sitexgraphics' Air or an open source solution such as Pixie or Aqsis.
RenderMan Shading Language defines standalone functions and five types of shaders: surface, light, volume, imager and displacement shaders.
An example of a surface shader that defines a metal surface is:
surfacemetal(floatKa=1;floatKs=1;floatroughness=0.1;){normalNf=faceforward(normalize(N),I);vectorV=-normalize(I);Oi=Os;Ci=Os*Cs*(Ka*ambient()+Ks*specular(Nf,V,roughness));}Shaders express their work by reading and writing special variables such as Cs (surface color), N (normal at given point), and Ci (final surface color). The arguments to the shaders are global parameters that are attached to objects of the model (so one metal shader can be used for different metals and so on). Shaders have no return values, but functions can be defined which take arguments and return a value. For example, the following function computes vector length using the dot product operator ".":
floatlength(vectorv){returnsqrt(v.v);/* . is a dot product */}| | This graphics software–related article is a stub. You can help Wikipedia by expanding it. |
The RenderMan Interface Specification, or RISpec in short, is an open API developed by Pixar Animation Studios to describe three-dimensional scenes and turn them into digital photorealistic images. It includes the RenderMan Shading Language.
The Phong reflection model is an empirical model of the local illumination of points on a surface designed by the computer graphics researcher Bui Tuong Phong. In 3D computer graphics, it is sometimes referred to as "Phong shading", particularly if the model is used with the interpolation method of the same name and in the context of pixel shaders or other places where a lighting calculation can be referred to as “shading”.
Shading refers to the depiction of depth perception in 3D models or illustrations by varying the level of darkness. Shading tries to approximate local behavior of light on the object's surface and is not to be confused with techniques of adding shadows, such as shadow mapping or shadow volumes, which fall under global behavior of light.
Ray casting is the methodological basis for 3D CAD/CAM solid modeling and image rendering. It is essentially the same as ray tracing for computer graphics where virtual light rays are "cast" or "traced" on their path from the focal point of a camera through each pixel in the camera sensor to determine what is visible along the ray in the 3D scene. The term "Ray Casting" was introduced by Scott Roth while at the General Motors Research Labs from 1978–1980. His paper, "Ray Casting for Modeling Solids", describes modeled solid objects by combining primitive solids, such as blocks and cylinders, using the set operators union (+), intersection (&), and difference (-). The general idea of using these binary operators for solid modeling is largely due to Voelcker and Requicha's geometric modelling group at the University of Rochester. See solid modeling for a broad overview of solid modeling methods. This figure on the right shows a U-Joint modeled from cylinders and blocks in a binary tree using Roth's ray casting system in 1979.
Perlin noise is a type of gradient noise developed by Ken Perlin in 1983. It has many uses, including but not limited to: procedurally generating terrain, applying pseudo-random changes to a variable, and assisting in the creation of image textures. It is most commonly implemented in two, three, or four dimensions, but can be defined for any number of dimensions.
Lambertian reflectance is the property that defines an ideal "matte" or diffusely reflecting surface. The apparent brightness of a Lambertian surface to an observer is the same regardless of the observer's angle of view. More precisely, the reflected radiant intensity obeys Lambert's cosine law, which makes the reflected radiance the same in all directions. Lambertian reflectance is named after Johann Heinrich Lambert, who introduced the concept of perfect diffusion in his 1760 book Photometria.
In computer graphics, a shader is a computer program that calculates the appropriate levels of light, darkness, and color during the rendering of a 3D scene—a process known as shading. Shaders have evolved to perform a variety of specialized functions in computer graphics special effects and video post-processing, as well as general-purpose computing on graphics processing units.
Reyes rendering is a computer software architecture used in 3D computer graphics to render photo-realistic images. It was developed in the mid-1980s by Loren Carpenter and Robert L. Cook at Lucasfilm's Computer Graphics Research Group, which is now Pixar. It was first used in 1982 to render images for the Genesis effect sequence in the movie Star Trek II: The Wrath of Khan. Pixar's RenderMan was an implementation of the Reyes algorithm, It has been deprecated as of 2016 and removed as in RenderMan 21. According to the original paper describing the algorithm, the Reyes image rendering system is "An architecture for fast high-quality rendering of complex images." Reyes was proposed as a collection of algorithms and data processing systems. However, the terms "algorithm" and "architecture" have come to be used synonymously in this context and are used interchangeably in this article.
A shading language is a graphics programming language adapted to programming shader effects. Shading languages usually consist of special data types like "vector", "matrix", "color" and "normal".
OBJ is a geometry definition file format first developed by Wavefront Technologies for its Advanced Visualizer animation package. The file format is open and has been adopted by other 3D graphics application vendors.
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 to give developers more direct control of the graphics pipeline without having to use ARB assembly language or hardware-specific languages.
3D rendering is the 3D computer graphics process of converting 3D models into 2D images on a computer. 3D renders may include photorealistic effects or non-photorealistic styles.
3Delight, or as currently known as 3DelightNSI, is 3D computer graphics software that runs on Microsoft Windows, MacOS and Linux. It is developed by Illumination Research. It is both a photorealistic and NPR path tracing offline renderer based on its NSI API scene description and on OSL for shading. It has been used to render full CGI animation and VFX for numerous feature films. It comes with supported, open source plug-in integrations for several DCC applications, such as Maya, Houdini, Cinema4D, Katana, OpenUSD Hydra, and a democratic free license that allows for commercial use. It also provides a fully distributed cloud rendering service called 3Delight Cloud.
The Blinn–Phong reflection model, also called the modified Phong reflection model, is a modification developed by Jim Blinn to the Phong reflection model.
Computer graphics lighting is the collection of techniques used to simulate light in computer graphics scenes. While lighting techniques offer flexibility in the level of detail and functionality available, they also operate at different levels of computational demand and complexity. Graphics artists can choose from a variety of light sources, models, shading techniques, and effects to suit the needs of each application.
Shadeop is a term used in computer graphics rendering to refer to an atomic, built-in function used in a shader.
A vertex in computer graphics is a data structure that describes certain attributes, like the position of a point in 2D or 3D space, or multiple points on a surface.
Metal is a low-level, low-overhead hardware-accelerated 3D graphic and compute shader API created by Apple, debuting in iOS 8. Metal combines functions similar to OpenGL and OpenCL in one API. It is intended to improve performance by offering low-level access to the GPU hardware for apps on iOS, iPadOS, macOS, and tvOS. It can be compared to low-level APIs on other platforms such as Vulkan and DirectX 12.
This is a glossary of terms relating to computer graphics.
Physically based rendering (PBR) is a computer graphics approach that seeks to render images in a way that models the lights and surfaces with optics in the real world. It is often referred to as "Physically Based Lighting" or "Physically Based Shading". Many PBR pipelines aim to achieve photorealism. Feasible and quick approximations of the bidirectional reflectance distribution function and rendering equation are of mathematical importance in this field. Photogrammetry may be used to help discover and encode accurate optical properties of materials. PBR principles may be implemented in real-time applications using Shaders or offline applications using Ray tracing (graphics) or Path tracing.