The RenderMan Interface - Paul Bourke

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may be nested to any depth, subject to their individual restrictions, but it is never legal for the blocks to overlap. 4.1 Options The graphics state has various options that must be set before rendering a frame. The complete set of options includes: a description of the camera, which controls all aspects of the imaging process (including the camera position and the type of projection); a description of the display, which controls the output of pixels (including the types of images desired, how they are quantized and which device they are displayed on); as well as renderer run-time controls (such as the hidden surface algorithm to use). 4.1.1 Camera The graphics state contains a set of parameters that define the properties of the camera. The complete set of camera options is described in Table 4.1, Camera Options. The viewing transformation specifies the coordinate transformations involved with imaging the scene onto an image plane and sampling that image at integer locations to form a raster of pixel values. A few of these procedures set display parameters such as resolution and pixel aspect ratio. If the rendering program is designed to output to a particular display device these parameters are initialized in advance. Explicitly setting these makes the specification of an image more device dependent and should only be used if necessary. The defaults given in the Camera Options table characterize a hypothetical framebuffer and are the defaults for picture files. The camera model supports near and far clipping planes that are perpendicular to the viewing direction, as well as any number of arbitrary user-specified clipping planes. Depth of field is specified by setting an f-stop, focal length, and focal distance just as in a real camera. Objects located at the focal distance will be sharp and in focus while other objects will be out of focus. The shutter is specified by giving opening and closing times. Moving objects will blur while the camera shutter is open. The imaging transformation proceeds in several stages. Geometric primitives are specified in the object coordinate system. This canonical coordinate system is the one in which the object is most naturally described. The object coordinates are converted to the world coordinate system by a sequence of modeling transformations. The world coordinate system is converted to the camera coordinate system by the camera transformation. Once in camera coordinates, points are projected onto the image plane or screen coordinate system by the projection and its following screen transformation. Points on the screen are finally mapped to a device dependent, integer coordinate system in which the image is sampled. This is referred to as the raster coordinate system and this transformation is referred to as the raster transformation. These various coordinate systems are summarized in Table 4.2 Point Coordinate Systems. These various coordinate systems are established by camera and transformation commands. The order in which camera parameters are set is the opposite of the order in which the 19
Camera Option Type Default Description Horizontal Resolution integer 640* The horizontal resolution in the output image. Vertical Resolution integer 480* The vertical resolution in the output image. Pixel Aspect Ratio float 1.0* The ratio of the width to the height of a single pixel. Crop Window 4 floats (0,1,0,1) The region of the raster that is actually rendered. Frame Aspect Ratio float 4/3* The aspect ratio of the desired image. Screen Window 4 floats (-4/3,4/3,-1,1)* The screen coordinates (coordinates after the projection) of the area to be rendered. Camera Projection token “orthographic” The camera to screen projection. World to Camera transform identity The world to camera transformation. Near and Far Clipping 2 floats (epsilon,infinity) The positions of the near and far clipping planes. Other Clipping Planes list of planes – Additional planes that clip geometry from the scene. f-Stop float infinity Parameters controlling depth of field. Focal Length float – Focal Distance float – Shutter Open float 0 The times when the shutter opens and closes. Shutter Close float 0 * Interrelated defaults Table 4.1: Camera Options 20
Page 1 and 2: The RenderMan Interface Version 3.2
Page 3 and 4: TABLE OF CONTENTS List of Figures L
Page 5 and 6: 12.1 Surface Shaders . . . . . . .
Page 7 and 8: Section I DIFFERENCES BETWEEN VERSI
Page 9 and 10: LIST OF TABLES 4.1 Camera Options .
Page 11 and 12: PREFACE This document is version 3.
Page 13 and 14: Section 1 INTRODUCTION The RenderMa
Page 15 and 16: created using this language. This l
Page 17 and 18: Depth of Field The ability to simul
Page 19 and 20: typedef RtPointer typedef RtPointer
Page 21 and 22: RiContext (ctx1); ... There is no R
Page 23 and 24: Section 3 RELATIONSHIP TO THE RENDE
Page 25 and 26: through the interface. Any place wh
Page 27 and 28: RtContextHandle RiGetContext ( void
Page 29: RiWorldBegin (); ... RiColor (...);
Page 33 and 34: ottom top left right Screen Window
Page 35 and 36: EXAMPLE RiFrameAspectRatio (4.0/3.0
Page 37 and 38: not support the special projection
Page 39 and 40: This procedure sets the times at wh
Page 41 and 42: Output depth values are the camera-
Page 43 and 44: A particular renderer implementatio
Page 45 and 46: Renderers may additionally produce
Page 47 and 48: The number of color components, n,
Page 49 and 50: 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
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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
Page 97 and 98:
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
Page 161 and 162:
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
Page 213 and 214:
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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The RenderMan Interface - Paul Bourke

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