The RenderMan Interface - Paul Bourke

SolidBegin ( ”difference” );
SolidBegin ( ”primitive” );
RiSphere ( 1.0, -1.0, 1.0, 360.0, RI NULL);
RiSolidEnd ();
SolidBegin ( ”primitive” );
RiDisk( 2.0, 0.5, 360.0, RI NULL);
RiCylinder( 0.5, -2.0, 2.0, 360.0, RI NULL);
RiDisk( -2.0, 0.5, -360.0, RI NULL);
RiSolidEnd ();
RiSolidEnd ();
When performing a difference the sense of the orientation of the surfaces being subtracted
is automatically reversed.
Attributes may be changed freely inside solids. Each section of a solid’s surface can have
a different surface shader and color. For consistency a single solid should have a single
interior and exterior volume shader.
If the Solid Modeling optional capability is not supported by a particular implementation, all
primitives are rendered as a collection of surfaces, and the spatial set operators are ignored.
5.10 Retained Geometry
A single geometric primitive or a list of geometric primitives may be retained by enclosing
them with RiObjectBegin and RiObjectEnd. The RenderMan Interface allocates and returns
an RtObjectHandle for each retained object defined in this way. This handle can subsequently
be used to reference the object when creating instances with RiObjectInstance.
Objects are not rendered when they are defined within an RiObjectBegin-RiObjectEnd
block; only an internal definition is created.
Transformations, and even Motion blocks, may be used inside an Object block, though
they obviously imply a relative transformation to the coordinate system active when the
Object is instanced. All of an object’s attributes are inherited at the time it is instanced, not
at the time at which it is created. So, for example, shader assignments or other attributes
are not allowed within an Object block. The only exception is RiBasis, which may set the
interpolation basis matrix used for RiPatch, RiPatchMesh, or RiCurves primitives that
are within the Object block.
RtObjectHandle
RiObjectBegin ()
RiObjectEnd ()
RiObjectBegin starts the definition of an object and return a handle for later use with
RiObjectInstance. If the handle returned is NULL, an object could not be created.
RiObjectEnd ends the definition of the current object.
RIB BINDING
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