转：怎样高效的使用RiProcedure

http://cid-a6597afda81373ba.spaces.live.com/blog/cns!A6597AFDA81373BA!295.entry

如何更加高效的使用RiProcedure

A traditional procedural primitive calls Subdivide() function to create RIB stream as soon as its bounding box is hit. But in this example, Subdivide() does not create any RIB stream. It invokes another procedural for several times instead. We call it Proxy. We call the procedural invoked by Proxy is called Real.

The idea is to divide large data set into a number of smaller fragments, each has its own smaller bounding box. Real procedural will not trigger RIB stream until it’s bounding box is hit. And RenderMan will release memory allocated to a Real as soon as it has been rendered. This method uses memory a lot more efficiently than emitting all RIB stream in one piece.

#include <stdio.h>
#include <stdlib.h>

#include "DProxy.h"
#include "DReal.h"

#ifdef _WIN32
#define export __declspec(dllexport)
#define strtok_r(str,delim,saveptr) strtok((str),(delim))
#else
#define export
#endif

extern "C" {
/* Declarations */
export RtPointer ConvertParameters(RtString paramstr);
export RtVoid Subdivide(RtPointer data, float detail);
export RtVoid Free(RtPointer data);
export RtVoid Subdivide_real(RtPointer data, float detail);
export RtVoid Free_real(RtPointer data);
}

export RtPointer ConvertParameters(RtString paramstr)
{
DProxy *data = new DProxy(paramstr);
return data;
}

export RtVoid Subdivide(RtPointer blinddata, RtFloat detailsize)
{
DProxy *data = static_cast< DProxy*>(blinddata);
data->init();

DReal* realdata;
RtBound bound = {-.5, .5, -.5, .5, -.5, .5};
for(unsigned i=0; i< data->getNumData(); i++) {
realdata = new DReal();

float noi = float(random()%131)/262.f+0.03;

realdata->setRadius( noi);

RiTransformBegin();

float noix = (0.5 - float(random()%271)/271.f)*5;
float noiy = (0.5 - float(random()%219)/219.f)*5;
float noiz = (0.5 - float(random()%253)/253.f)*5;

RiTranslate(noix, noiy, noiz);

bound[0] = -noi; bound[1] = noi;
bound[2] = -noi; bound[3] = noi;
bound[4] = -noi; bound[5] = noi;

RiProcedural(realdata, bound, Subdivide_real, Free_real);

RiTransformEnd();
}
}

export RtVoid Subdivide_real(RtPointer blinddata, RtFloat detailsize)
{
DReal *data = static_cast< DReal*>(blinddata);
data->emit();
}

export RtVoid Free(RtPointer blinddata)
{
DProxy *data = static_cast< DProxy*>(blinddata);
delete data;
}

export RtVoid Free_real(RtPointer blinddata)
{
DReal *data = static_cast< DReal*>(blinddata);
delete data;
}