The RenderMan Interface - Paul Bourke

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Arrays The characters ‘[’ and ‘]’ are self-delimiting tokens that specify the construction of an array of numbers or strings. An array cannot contain both numbers and strings. If an array contains at least one floating point value, all integer values in the array are converted to floating point. Arrays of numbers are used, for example, to specify matrices and points. Arrays of strings are used in specifying options. Binary encoding For efficiency, compressed binary encodings of many types of data are also supported. These encodings may be freely intermixed with the normal ASCII strings. The two encodings are differentiated by the top bit of the eight-bit bytes in the input stream. If the top bit is zero, then the byte is interpreted as a 7-bit ASCII character. Otherwise, if the top bit is one, the byte is interpreted as a compressed token according to the rules given below. This differentiation is not applied within string constants or the parameter bytes which follow the initial byte of a compressed token. Table C.1 shows the encoding for compressed tokens with all byte values displayed in octal. Values Span Interpreted as... 0–0177 128 ASCII characters 0200–0217 16 encoded integers and fixed-point numbers 0220–0237 16 encoded strings of no more than 15 characters 0240–0243 4 encoded strings longer than 15 characters 0244 1 encoded single precision IEEE floating point value 0245 1 encoded double precision IEEE floating point value 0246 1 encoded RI request 0247–0307 32 nothing (reserved) 0310–0313 4 encoded single precision array (length follows) 0314 1 define encoded request 0315–0316 2 define encoded string token 0317–0320 2 interpolate defined string 0321–0377 46 nothing (reserved) Table C.1: Binary Encoding Four separate data types are supported: signed integers, signed fixed-point numbers, strings, and floating-point numbers. Integers and fixed-point numbers are encoded using a single format while strings are encoded with two different formats according to the length of the string. Both single- and double-precision IEEE format floating-point numbers are supported. Strings that are used repeatedly can be defined and then subsequently referenced with a compact form that is usually more space efficient. Arrays of floating-point values are directly supported for efficiency (they can also be specified using the array definition symbols). Single-precision matrices (arrays of 16 floatingpoint values) can be specified in a total of 66 bytes, while other arrays may require slightly more. 177
In the following sections the syntax for each encoding is presented as a sequence of bytes separated by ‘|’ symbols. Numeric values should interpreted as octal values (base 8) if they have a leading ‘0’ digit, otherwise as decimal values. Items shown in angle brackets ‘< >’ represent varying items, such as a numeric value or string that is being encoded. Integers and fixed-point numbers. Integer and fixed-point values can be transmitted in 2-5 bytes. The encoded token has the form: 0200 + (d · 4) + w | where the next w + 1 bytes form a signed integer taken from the most significant byte to the least significant byte, and the bottom d bytes are after the decimal point. Strings. Strings shorter than 16 bytes, say w bytes, can be transmitted with a prefixing token: 0220 + w | Other strings must use a prefixing token followed by a variable length string length, and then followed by the string itself: 0240 + l | | where l + 1 is the number of bytes needed to specify the length of the string, 0 ≤ l ≤ 3. The string length is an unsigned value and is transmitted from most significant byte to least significant byte. Unlike unencoded strings, there are no escape or special characters in an encoded string. Defining strings. For strings that are to be transmitted repeatedly, a string token can be defined with: 0315 + w | | where w + 1 is the number of bytes needed to specify the token, (1 or 2), and the string being defined is transmitted in an encoded or unencoded form. The token is an unsigned value and is transmitted from most significant byte to least significant byte. For efficiency, the range of tokens defined should be as compact as possible. Referencing defined strings. To interpolate a string that has previously been defined (as described above), the following is used: 0317 + w | where the token refers to the string to be interpolated. Floating-point values. Floating-point values are transmitted in single-precision or doubleprecision IEEE format from most significant byte to least significant byte. Single-precision floating-point values occupy four bytes in the input stream and double-precision values occupy eight bytes. Floating point arrays. Aggregates of single-precision floating-point values can be transmitted with a prefixing token byte. Variable sized arrays are transmitted as a token byte followed by a variable length array size, and then followed by the array itself: 0310 + l | | The array length is an unsigned value, l + 1 bytes long, and is transmitted from most 178
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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
Page 137 and 138: • 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: Comments Any occurrence of the ’#
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 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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The RenderMan Interface - Paul Bourke

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