The RenderMan Interface - Paul Bourke

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A more efficient method for accessing subdivision routines is to write them as dynamic shared objects (DSOs) 1 , and dynamically load them into the renderer executable at run-time. In this case, you write your subdivision and free routines in C, exactly as you would if you were writing them to be linked into the renderer using the C RiProcedural interface. DSOs are compiled with special compiler options to make them run-time loadable and are specified in the RIB file by the name of the shared object file. The renderer will load the DSO the first time that the subdivision routine must be called, and from then on, it is called as if (and executes as fast as if) it were statically linked. DSOs are more efficient than external programs because they avoid the overhead of interprocess communication. When writing a procedural primitive DSO, you must create three specific public subroutine entry points, named Subdivide, Free, and ConvertParameters. Subdivide is a standard RiProcedural() primitive subdivision routine, taking a blind data pointer to be subdivided and a floating-point detail to estimate screen size. Free is a standard RiProcedural primitive free routine, taking a blind data pointer to be released. ConvertParameters is a special routine that takes a string and returns a blind data pointer. It will be called exactly once for each DynamicLoad procedural primitive in the RIB file, and its job is to convert a printable string version of the progenitor’s blind data (which must be in ASCII in the RIB file), into something that the Subdivide routine will accept. The C prototypes for these functions are as follows: RtPointer ConvertParameters(char * initialdata ); void Subdivide(RtPointer blinddata, RtFloat detailsize ); void Free( RtPointer blinddata ); Note that if the DSO Subdivide routine wants to recursively create child procedural primitives of the same type as itself, it should specify a direct recursive call to itself, with RiProcedural(newdata,newbound,Subdivide,Free), not call itself as a DynamicLoad procedural. The latter would eventually just call the former after wasting time checking for and reloading the DSO. The conventions for how dynamic objects are compiled are implementation-dependent (and also very likely OS-dependent). RIB BINDING Procedural ”DynamicLoad” [dsoname paramdata] [boundingbox] The argument list is an array of two strings. The first element is the name of the shared object file that contains the three required entry points and has been compiled and prelinked as described earlier. The second element is the ASCII printable string that represents the initial data to be sent to the ConvertParameters routine. The boundingbox is an array of six floating-point numbers, which is xmin, xmax, ymin, ymax, zmin, zmax in the current object space. EXAMPLE RtString args[] = { ”mydso.so”, ”” }; RtBound mybound = { -1, 1, -1, 1, 0, 6 }; RiProcedural ((RtPointer)args, mybound, RiProcDynamicLoad, RiProcFree); 1 on some systems called dynamically linked libraries, or DLLs 91
Procedural ”DynamicLoad” [ ”mydso.so” ”” ] [ -1 1 -1 1 0 6 ] SEE ALSO RiProcedural, RiProcDelayedReadArchive, RiProcRunProgram 5.8 Implementation-specific Geometric Primitives Additional geometric primitives can be specified using the following procedure. RiGeometry ( RtToken type, ...parameterlist...) This procedure provides a standard way of defining an implementation-specific geometric primitive. The values supplied in the parameter list for each primitive is implementation specific. RIB BINDING Geometry name ...parameterlist... EXAMPLE RiGeometry(”teapot”, RI NULL); 5.9 Solids and Spatial Set Operations All of the previously described geometric primitives can be used to define a solid by bracketing a collection of surfaces with RiSolidBegin and RiSolidEnd. This is often referred to as the boundary representation of a solid. When specifying a volume it is important that boundary surfaces completely enclose the interior. Normally it will take several surfaces to completely enclose a volume since, except for the sphere, the torus, and potentially a periodic patch or patch mesh, none of the geometric primitives used by the rendering interface completely enclose a volume. A set of surfaces that are closed and non-self-intersecting unambiguously defines a volume. However, the RenderMan Interface performs no explicit checking to ensure that these conditions are met. The inside of the volume is the region or set of regions that have finite volume; the region with infinite volume is considered outside the solid. For consistency the normals of a solid should always point outwards. 92
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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
Page 51 and 52: RIB BINDING Color c0 c1... cn Color
Page 53 and 54: An area light source is defined by
Page 55 and 56: The sequencenumber is the integer l
Page 57 and 58: 4.2.5 Displacement shading The grap
Page 59 and 60: SEE ALSO RiExterior RiAtmosphere Ri
Page 61 and 62: Matte onoff EXAMPLE RiMatte (RI TRU
Page 63 and 64: object foo2 will be drawn when the
Page 65 and 66: the exterior is the region adjacent
Page 67 and 68: RiIdentity ( ); SEE ALSO RiTransfor
Page 69 and 70: RiScale ( RtFloat sx, RtFloat sy, R
Page 71 and 72: 4.3.2 Transformation stack Transfor
Page 73 and 74: Section 5 GEOMETRIC PRIMITIVES The
Page 75 and 76: Information Name Type Class Floats
Page 77 and 78: No checking is done by the RenderMa
Page 79 and 80: 5.2 Patches Patches can be either u
Page 81 and 82: U V 0 1 2 3 12 13 14 15 4 5 6 7 8 9
Page 83 and 84: 10 x 7 Aperiodic Bezier Bicubic Pat
Page 85 and 86: SEE ALSO 2 2 [ 0 0 1 1 ] 0 1 ”Pw
Page 87 and 88: parameterlist is a list of token-ar
Page 89 and 90: Requests a sphere defined by the fo
Page 91 and 92: Hyperboloid 0 0 0 .5 0 0 270 ”Cs
Page 93 and 94: z N z V point2 height U x x y 0 max
Page 95 and 96: particle. If a primitive variable i
Page 97 and 98: The code array is a sequence of mac
Page 99 and 100: is an array of floats that define t
Page 101: The helper program generates geomet
Page 105 and 106: SolidBegin ( ”difference” ); So
Page 107 and 108: Section 6 MOTION Some rendering pro
Page 109 and 110: Transformations Geometry Shading Ri
Page 111 and 112: channels (usually an RGB color) can
Page 113 and 114: Image Forward Axis Up Axis Right Ax
Page 115 and 116: ErrorHandler ”ignore” ErrorHand
Page 117 and 118: Part II The RenderMan Shading Langu
Page 119 and 120: spaces (such as CMYK or pseudocolor
Page 121 and 122: transmit reflect transmit P E light
Page 123 and 124: Section 10 RELATIONSHIP TO THE REND
Page 125 and 126: Section 11 TYPES The Shading Langua
Page 127 and 128: Coordinate System ”shader” ”c
Page 129 and 130: As in C, individual array elements
Page 131 and 132: Light Source E Vantage Point N L Il
Page 133 and 134: Surface Element to Illuminate L N I
Page 135 and 136: 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
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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;
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A.6 Imager Shaders A.6.1 Background
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variable definitions ; variables va
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triple sixteentuple arrayindex: [ e
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Logical expressions have the value
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typedef RtPointer RtContextHandle;
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RiOptionV(RtToken name, RtInt n, Rt
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RtInt n, RtToken tokens[], RtPointe
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#define RIE_NOTATTRIBS ((RtInt)26)
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Comments Any occurrence of the ’#
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In the following sections the synta
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C.2.2 Error handling There are two
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adhandle badparamlist badripcode ba
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v e r s i o n 212 # version 003 007
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Using RIB File structuring conventi
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Attribute Format PixelFilter Shadin
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##Include filename This entry allow
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D.2.1 RIB Entity File example ##Ren
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Motion Blur Programmable Shading Di
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} E.4 Gaussian Filter RtFloat RiGau
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Appendix G RENDERMAN INTERFACE QUIC
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Function RiOpacity (color) RiOption
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Geometric Primitives (continued) Fu
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Function abs(x) Math Functions Desc
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Function area(P) calculatenormal(P)
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Texture Mapping Functions Function
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RiInterior 47 RiLightSource 42 RiMa
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and uniform variables on an RiNuPat
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Statement About Pixar’s Copyright
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