RE_OcclusionQuery.h

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/*
 * PROPRIETARY INFORMATION.  This software is proprietary to
 * Side Effects Software Inc., and is not to be reproduced,
 * transmitted, or disclosed in any way without written permission.
 *
 * NAME:        RE_OcclusionQuery.h ( RE Library, C++)
 *
 * COMMENTS:
 *
 *    This class implements the GL_ARB_occlusion_query feature, which allows
 *    multi-pass rendering to determine how many pixels in a batch of drawing
 *    commands were accepted by Z-culling.
 *
 *    Only one query can be active at a time.
 *
 *    The body of this class is implemented in RE_OGLQuery.
 *
 *    If 'boolean_result' is passed to RE_OcclusionQuery, then a zero/one
 *    result will be passed back from getNumDrawn(). This may have a 
 *    performance benefit for some hardware. 
 */
#ifndef RE_OCCLUSION_QUERY_H
#define RE_OCCLUSION_QUERY_H

#include "RE_OGLQuery.h"

class RE_Render;

class RE_API RE_OcclusionQuery : public RE_OGLQuery
{
public:
    enum RE_OcclusionResult
    {
        BOOLEAN,
        NUM_SAMPLES
    };
    
                RE_OcclusionQuery(RE_OcclusionResult result = NUM_SAMPLES);
                ~RE_OcclusionQuery() override {}

   bool         begin(RE_Render *r) override;
   void         end(RE_Render *r) override;

   bool         getAnySamplesDrawn(RE_Render *r)
                   { return (bool)(getIntResult(r)!=0); }

   int          getNumDrawn(RE_Render *r)
                {
                    if(myBooleanQuery)
                        return (getIntResult(r)!=0) ? 1 : 0;
                    return getIntResult(r);
                }

private:
   bool         myBooleanQuery;
};

#endif