The RenderMan Interface - Paul Bourke

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significant byte to least significant byte. Defining RI requests. Before an encoded request can be used, it must first be bound to its ASCII equivalent with: 0314 | | where the code is one byte and string is the ASCII form of the request. Referencing defined RI requests. A previously defined RI request is referenced with two bytes; a prefixing token, 0246, followed by a request code. 0246 | This means that no more than 256 RI requests can be directly encoded in the binary protocol. Example. Consider the following sequence of RIB commands: version 3.03 ErrorHandler ”print” Display ”test.25.pic” ”file” ”rgba” Format 512 307 1 Clipping 0.1 10000 WorldBegin Declare ”direction” ”point” LightSource ”windowlight” 0 ”direction” [1 0 -0.1] Color [1 1 1] Orientation ”lh” Sides 1 AttributeBegin MotionBegin [0 1] Translate 1.91851 0.213234 1.55 Sphere 2 -0.3 1.95 175 MotionEnd AttributeEnd This could translate into the encoded sequence of bytes shown in Figure C.1. Version Number The RIB stream supports a special version request that is used internally to ensure that the syntax of the stream is compatible with the parser being used. version num Specifies the protocol version number of the RIB stream. The stream specified in this document is version 3.03. A RIB parser may refuse to parse streams with incompatible version numbers. 179
C.2.2 Error handling There are two types of errors that may be encountered while processing a RIB input stream: syntactic errors and semantic errors. Syntactic errors occur when the stream of tokens fails to form a syntactically legal statement or request. For example, a syntactic error occurs when a required parameter is missing, or when a string is left unterminated. Semantic errors occur when a syntactically legal statement contains incorrect data; e.g., when a parameter that must be non-negative is specified to be -1. RIB defines a number of syntactic errors and a limited number of semantic errors. In theory RIB should be responsible only for syntactic errors. However, due to the weak typing of programming languages such as C, semantic errors that can not be easily recognized within the RenderMan Interface software are checked at the RIB level. For example, RIB checks arrays that are to be converted to matrices to be sure they have 16 values. Table C.2 shows the set of errors recognized by RIB. Detailed descriptions of the errors are given below. All errors encountered by a RIB interpreter require some associated action to be performed. In the case of syntax errors, if input processing is to be continued, the input scanner must resynchronize itself with the input stream. This synchronization is done by reading and discarding tokens from the input stream until a valid RIB request token is encountered. That is, any tokens between the point of the syntax error and the next request token are discarded. The protocol has been designed so that no more than one request (along with any associated parameters) must be discarded when recovering from an error. Errors are handled in one of three ways: • They are ignored and the rendering process will proceed to its completion no matter what input stream is provided. • They cause diagnostic messages to be generated on the renderer’s standard error stream, but they are otherwise ignored (the default). • The first error causes a diagnostic message to be generated and the renderer terminates immediately without creating an image. If the RIB interpreter is acting as a network server, in direct communication with a client application, the interpreter may send parsing error signals back to the client. These signals take the form of the following RIB requests, though they are not valid in the client-to-server stream. None of these error requests have arguments. Note that some errors may not be recognized immediately by a RIB interpreter upon parsing a request. This may be due to buffering or queuing built into the interface between the intepreter and the renderer. In a client-server environment this may have implications for the client application. arraytoobig The interpreter was unable to allocate sufficient memory to store an array specified in the input stream. This error is dependent on the interpreter’s implementation. Good implementations of a RIB interpreter support arrays as large as memory will permit. 180
Page 1 and 2:
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
Page 139 and 140: This example integrates over a hemi
Page 141 and 142: Shader instance variable values can
Page 143 and 144: } return 2 * (vector noise(p)) - 1;
Page 145 and 146: These functions compute power and i
Page 147 and 148: The actual change in a variable is
Page 149 and 150: Return a unit vector in the directi
Page 151 and 152: Return surface normal given a point
Page 153 and 154: diffuse returns the diffuse compone
Page 155 and 156: prevent aliasing. If one set of tex
Page 157 and 158: 15.7.3 Shadow depth maps Shadow dep
Page 159 and 160: These functions access the value of
Page 161 and 162: The standard data names supported b
Page 163 and 164: } Oi = sum; Ci = Cs * Oi * (Ka + Kd
Page 165 and 166: path of the ray. The input Ci and O
Page 167 and 168: A.2.3 Metal surface surface metal(
Page 169 and 170: 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: In the following sections the synta
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 and 222: RiInterior 47 RiLightSource 42 RiMa
Page 223 and 224: and uniform variables on an RiNuPat
Page 225 and 226: Statement About Pixar’s Copyright
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