The RenderMan Interface - Paul Bourke

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Appendix I DIFFERENCES BETWEEN VERSION 3.2 AND 3.1 Several new API calls have been added to the RenderMan Interface: • New geometric primitives: RiSubdivisionMesh, RiPoints, RiCurves, RiBlobby. • New built-in procedural routines suitable to use as RiProcedural primitives: RiProcDelayedReadArchive, RiProcRunProgram, RiProcDynamicLoad. • Reading an existing RIB archive into the renderer at an arbitrary point in the command stream. RiReadArchive. • New routines affecting the graphics state: RiCoordSysTransform, RiClippingPlane. There is no longer an approved K&R C binding of the RenderMan Interface. Instead, only an ANSI C binding is described. All interfaces and examples are now shown in ANSI C in this document. The following data types have been added to the RenderMan Interface: vector, normal, matrix, hpoint, and to ri.h (as RtVector, RtNormal, and RtHpoint). The ri.h header file also now defines an RtInt to be an int, not a long. The storage classes vertex and constant have been added to the RenderMan Interface. A vertex primitive variable must supply the same number of data elements as are supplied for the position, ”P”, and interpolation is performed in the same manner as position. A constant primitive variable supplies a single data value for an entire geometric primitive (even an aggregate primitive, like a PointsPolygons). Descriptions of all the geometric primitives have been updated to explain the expected number of data elements for each storage class. ”NDC” space is now a standard space known to an implementation. Clarified that output depth values are camera space z values, not screen space values. Clarified that the type parameter of RiDisplay is not limited to be ”file” or ”framebuffer”, but may be any format or device type name supported by a particular implementation. The ”file” and ”framebuffer” names select the implementation’s default file format or framebuffer device. The RenderMan Interface 3.1 Specification was silent on the number of uniform and varying values supplied for primitive variables on RiNuPatch primitives. The number of varying 211
and uniform variables on an RiNuPatch has now officially been deemed to be computed as if the NuPatch is a nonperiodic uniform B-spline mesh, rather than a single B-spline patch. Details are given in Section 5.2 where the RiNuPatch primitive is described. The 3.1 spec implied that Shading Language variable initialization expressions could only be uniform. That restriction is lifted. The Shading Language variables du and dv are potentially varying, and are not restricted to be uniform as the 3.1 specification suggests. A number of new optional arguments to the Shading Language texturing functions have been added: ”blur”, ”sblur”, ”tblur”, ”filter”, ”fill”. Many new built-in functions, or new variants of existing functions, have been added to the Shading Language, including: inversesqrt, random, transform, vtransform, ntransform, determinant, concat, format, match, translate, rotate, scale, ctransform, ptlined, filterstep, noise, cellnoise, pnoise, specularbrdf, attribute, option, textureinfo, rendererinfo, min, max, clamp, mix, spline, atmosphere, displacement, lightsource, surface, Dtime. The illuminance statement has been expanded to accept category specifiers. Shading Language has added new variables: dtime and dPdtime. Rather than strictly requiring user-defined and nonstandard data to be typed using RiDeclare, such tokens can have their types specified “in-line” by prepending the type declaration to the token name. Renderers may output images composed of arbitrary data computed by shaders, in addition to “rgb” and so on. Such extra data may also be sent to different output files. We have clarified that interior and exterior volume shaders are not specific to CSG solids, but rather are shaders that alter the colors of rays spawned by trace() calls in the shaders of the primitive. RiArchiveRecord now takes ”verbatim” as the record type. We have clarified that in imager shaders, P is the raster space position of the pixel center, and not the point on any piece of scene geometry. We have changed the wording of the section that once described the required versus optional capabilities of RenderMan-compliant renderers. A few features previously described as optional, such as programmable shading, texture mapping, and trim curves, have been moved unambiguously to the list of requirements. There is still a list of “advanced features” that are no longer referred to as “optional,” but it is understood that algorithmic limitations may prevent some implementations from fully supporting those features. Object Instances are a bit more flexible in 3.2 than they were in 3.1. In particular, relative transformations and Motion blocks are allowed within Object definitions. Some changes have been made to the required standard shaders: they have been updated to make use of the new data types, the bumpy shader now does displacement instead of using the depricated bump() function, and there is now a standard background imager shader. 212
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The RenderMan Interface Version 3.2
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TABLE OF CONTENTS List of Figures L
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12.1 Surface Shaders . . . . . . .
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Section I DIFFERENCES BETWEEN VERSI
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LIST OF TABLES 4.1 Camera Options .
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PREFACE This document is version 3.
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Section 1 INTRODUCTION The RenderMa
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created using this language. This l
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Depth of Field The ability to simul
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typedef RtPointer typedef RtPointer
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RiContext (ctx1); ... There is no R
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Section 3 RELATIONSHIP TO THE RENDE
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through the interface. Any place wh
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RtContextHandle RiGetContext ( void
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RiWorldBegin (); ... RiColor (...);
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Camera Option Type Default Descript
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ottom top left right Screen Window
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EXAMPLE RiFrameAspectRatio (4.0/3.0
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not support the special projection
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This procedure sets the times at wh
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Output depth values are the camera-
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A particular renderer implementatio
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Renderers may additionally produce
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The number of color components, n,
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RiAttributeBegin () RiAttributeEnd
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RIB BINDING Color c0 c1... cn Color
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An area light source is defined by
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The sequencenumber is the integer l
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4.2.5 Displacement shading The grap
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SEE ALSO RiExterior RiAtmosphere Ri
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Matte onoff EXAMPLE RiMatte (RI TRU
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object foo2 will be drawn when the
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the exterior is the region adjacent
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RiIdentity ( ); SEE ALSO RiTransfor
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RiScale ( RtFloat sx, RtFloat sy, R
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4.3.2 Transformation stack Transfor
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Section 5 GEOMETRIC PRIMITIVES The
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Information Name Type Class Floats
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No checking is done by the RenderMa
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5.2 Patches Patches can be either u
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U V 0 1 2 3 12 13 14 15 4 5 6 7 8 9
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10 x 7 Aperiodic Bezier Bicubic Pat
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SEE ALSO 2 2 [ 0 0 1 1 ] 0 1 ”Pw
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parameterlist is a list of token-ar
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Requests a sphere defined by the fo
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Hyperboloid 0 0 0 .5 0 0 270 ”Cs
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z N z V point2 height U x x y 0 max
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particle. If a primitive variable i
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The code array is a sequence of mac
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is an array of floats that define t
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The helper program generates geomet
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Procedural ”DynamicLoad” [ ”m
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SolidBegin ( ”difference” ); So
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Section 6 MOTION Some rendering pro
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Transformations Geometry Shading Ri
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channels (usually an RGB color) can
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Image Forward Axis Up Axis Right Ax
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ErrorHandler ”ignore” ErrorHand
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Part II The RenderMan Shading Langu
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spaces (such as CMYK or pseudocolor
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transmit reflect transmit P E light
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Section 10 RELATIONSHIP TO THE REND
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Section 11 TYPES The Shading Langua
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Coordinate System ”shader” ”c
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As in C, individual array elements
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Light Source E Vantage Point N L Il
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Surface Element to Illuminate L N I
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Name Type Storage Class Description
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• conditional execution, • loop
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This example integrates over a hemi
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Shader instance variable values can
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} return 2 * (vector noise(p)) - 1;
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These functions compute power and i
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The actual change in a variable is
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Return a unit vector in the directi
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Return surface normal given a point
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diffuse returns the diffuse compone
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prevent aliasing. If one set of tex
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15.7.3 Shadow depth maps Shadow dep
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These functions access the value of
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The standard data names supported b
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} Oi = sum; Ci = Cs * Oi * (Ka + Kd
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path of the ray. The input Ci and O
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A.2.3 Metal surface surface metal(
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distantlight( float intensity = 1;
Page 171 and 172: A.6 Imager Shaders A.6.1 Background
Page 173 and 174: variable definitions ; variables va
Page 175 and 176: triple sixteentuple arrayindex: [ e
Page 177 and 178: Logical expressions have the value
Page 179 and 180: typedef RtPointer RtContextHandle;
Page 181 and 182: RiOptionV(RtToken name, RtInt n, Rt
Page 183 and 184: RtInt n, RtToken tokens[], RtPointe
Page 185 and 186: #define RIE_NOTATTRIBS ((RtInt)26)
Page 187 and 188: Comments Any occurrence of the ’#
Page 189 and 190: In the following sections the synta
Page 191 and 192: C.2.2 Error handling There are two
Page 193 and 194: adhandle badparamlist badripcode ba
Page 195 and 196: v e r s i o n 212 # version 003 007
Page 197 and 198: Using RIB File structuring conventi
Page 199 and 200: Attribute Format PixelFilter Shadin
Page 201 and 202: ##Include filename This entry allow
Page 203 and 204: D.2.1 RIB Entity File example ##Ren
Page 205 and 206: Motion Blur Programmable Shading Di
Page 207 and 208: } E.4 Gaussian Filter RtFloat RiGau
Page 209 and 210: Appendix G RENDERMAN INTERFACE QUIC
Page 211 and 212: Function RiOpacity (color) RiOption
Page 213 and 214: Geometric Primitives (continued) Fu
Page 215 and 216: Function abs(x) Math Functions Desc
Page 217 and 218: Function area(P) calculatenormal(P)
Page 219 and 220: Texture Mapping Functions Function
Page 221: RiInterior 47 RiLightSource 42 RiMa
Page 225 and 226: Statement About Pixar’s Copyright
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The RenderMan Interface - Paul Bourke

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