The RenderMan Interface - Paul Bourke

• perform gamma correction and dithering before quantization.
• produce picture files containing any combination of RGB, A, and Z. The resolutions
of these files must be as specified by the user.
• provide all of the geometric primitives described in the specification, and provide all
of the standard primitive variables applicable to each primitive.
• provide the ability to perform shading calculations using user-supplied RenderMan
Shading Language programs. (See Part II, The RenderMan Shading Language.)
• provide the ability to index texture maps, environment maps, and shadow depth
maps. (See the section on Basic texture maps.)
• provide the fifteen standard light source, surface, volume, displacement, and imager
shaders required by the specification. Any additional shaders, and any deviations
from the standard shaders presented in this specification, must be documented by
providing the equivalent shader expressed in the RenderMan Shading Language.
Rendering programs that implement the RenderMan Interface receive all of their data
through the interface. There must not be additional subroutines required to control or
provide data to the rendering program. Data items that are substantially similar to items
already described in this specification will be supplied through the normal mechanisms,
and not through any of the implementation-specific extension mechanisms (RiAttribute,
RiGeometry or RiOption). Rendering programs may not provide nonstandard alternatives
to the existing mechanisms, such as any alternate language for programmable shading.
1.1.2 Advanced Capabilities
Rendering programs may also provide one or more of the following advanced capabilities,
though it is recognized that algorithmic limitations of a particular implementation may
restrict its ability to provide the entire feature set. If a capability is not provided by an
implementation, a specific default is required (as described in the individual sections). A
subset of the full functionality of a capability may be provided by a rendering program.
For example, a rendering program might implement Motion Blur, but only of simple transformations,
or only using a limited range of shutter times. Rendering programs should
describe their implementation of the following optional capabilities using the terminology
in the following list.
Solid Modeling The ability to define solid models as collections of surfaces and combine
them using the set operations intersection, union and difference. (See the section on
Solids and Spatial Set Operations, p. 92.)
Level of Detail The ability to specify several definitions of the same model and have one
selected based on the estimated screen size of the model. (See the section on Detail,
p. 51.)
Motion Blur The ability to process moving primitives and antialias them in time. (See
Section 6, Motion.)
5