The RenderMan Interface - Paul Bourke

is an array of floats that define the bounding box of the primitive in object space.
subdividefunc is the routine that the renderer should call (when necessary) to have
the primitive subdivided. A bucket-based rendering scheme can potentially save
memory space by delaying this call until the bounding box overlaps a bucket that
must be rendered. The calling sequence for subdividefunc is:
(*subdividefunc)( RtPointer data, RtFloat detail )
where data is the parameter that was supplied in defining the primitive, and detail
is the screen area of the bound of the primitive. When subdividefunc is called, it is
expected to subdivide the primitive into other smaller procedural primitives or into
any number of non-procedural primitives. If the renderer can not determine the true
detail of the bound (e.g., if the geometric primitive data is being archived to a file),
subdividefunc may be called with a detail value equal to RI INFINITY. This should be
interpreted by the subdividefunc as a request for the immediate full generation of the
procedural primitive.
freefunc is a procedure that the rendering program calls to free the primitive when
the data is no longer needed. The calling sequence for freefunc is:
(*freefunc)( RtPointer data )
Note that the rendering program may call back multiple times with the same procedural
primitive, so the data area should not be overwritten or freed until the freefunc
is called.
The RenderMan Interface provides three standard built-in procedural primitives.
Their declarations are:
RtVoid RiProcDelayedReadArchive (RtPointer data, RtFloat detail);
RtVoid RiProcRunProgram (RtPointer data, RtFloat detail);
RtVoid RiProcDynamicLoad (RtPointer data, RtFloat detail);
These built-in procedurals are the subdivide routines. All three may use the single
built-in free function:
RtVoid RiProcFree (RtPointer data);
The RiProcFree procedure simply calls the standard C free() routine on data. The
meanings of the standard built-in procedural types are explained below.
RIB BINDING
Procedural procname [args] [bound]
The procedural name procname must be a built-in procedural, either one of the standard
ones described below or an implementation-specific procedural. The args parameter
is an array of strings supplying arguments to the built-in procedural. The
expected arguments for each type of procedural are explained in the following sections
on those primitives.
EXAMPLE
RtString args[] = { ”sodacan.rib” };
RtBound mybound = { -1, 1, -1, 1, 0, 6 };
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