UT/UT_PolyRaster.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.
 *
 * Produced by:
 *      Mark Elendt
 *      Side Effects Software Inc
 *      477 Richmond Street West
 *      Toronto, Ontario
 *      Canada   M5V 3E7
 *      416-504-9876
 *
 * NAME:        UT_PolyRaster.h ( UT Library, C++)
 *
 * COMMENTS:    Rasterize a polygon.  The following class is a virtual class
 *              which will "rasterize" a polygon.  For each pixel that the
 *              polygon covers, a filter weight will be computed and a callback
 *              will be invoked to process the pixel.  This can be used to
 *              render polygons to an image raster or to sample texture etc.
 *
 *              Currently, only triangles are supported.
 *
 *              If a sample table is set, then the sample table will be used
 *              for computation, otherwise "perfect" filtering will be done.
 *              "perfect" filtering is more expensive than sample table
 *              evaluation.
 */

#ifndef __UT_PolyRaster__
#define __UT_PolyRaster__

#include "UT_API.h"
#include "UT_Math.h"

class UT_Vector3;
class UT_prEdge;
class UT_Filter;
class UT_FilterSampleTable;

class UT_API UT_PolyRaster {
public:
             UT_PolyRaster();
    virtual ~UT_PolyRaster();

#if 0
    void        setSampleTable(UT_FilterSampleTable *table)
                {
                    mySampleTable = table;
                }
#endif
    void        setFilterWidth(fpreal x=1, fpreal y=1)
                {
                    myXSFilter = x * 0.5F;
                    myYSFilter = y * 0.5F;
                }
    void        setWindow(fpreal xl, fpreal xr, fpreal yb, fpreal yt)
                {
                    myXMin = xl; myXMax = xr;
                    myYMin = yb; myYMax = yt;
                }
    void        setResolution(int xsamp, int ysamp)
                {
                    myXres = xsamp;
                    myYres = ysamp;
                }

    // After all the variables are set, please call initialize.
    void        initialize();

    // The sample() method is a callback which will simply return the pixel
    // position and the weight.
    virtual void        sample(int x, int y, fpreal weight);

    // Rasterize the polygon and call the sample() method for each pixel
    // covered.  If the cliptowindow variable is 0, pixel values outside of the
    // resolution may be generated.
    void        rasterize(const float v0[2], const float v1[2],
                          const float v2[2], int cliptowindow = 1);

protected:
    float                myXFilter, myYFilter;
    float                myIXFilter, myIYFilter;
    float                myXSFilter, myYSFilter;
    float                myXMin, myXMax, myYMin, myYMax;
    int                  myXres, myYres;

private:
    void                 rasterize(UT_prEdge *head, int clipx) const;
    fpreal               filterWeight(const float v0[2], const float v1[2],
                                        const float v2[2]) const;

    // This clipOneEdge will generate a polygon for the filter region
    int                  clipOneEdge(fpreal xl, fpreal xr, fpreal yb, fpreal yt,
                                     float vtx[][2],
                                     const UT_prEdge &edge) const;
    int                  genericClip(const float vtx[][2], int nvtx,
                                     float result[][2],
                                     const UT_prEdge &e0) const;
    fpreal               genericWeight(float vtx[][2],
                                        int nvtx) const
                         {
                             if (nvtx < 3) return nvtx == -1;
                             return computeWeight(vtx, nvtx);
                         }
    int                  toScreenX(fpreal sx) const
                            { return (int)((sx-myXMin)*myIXSinc); }
    int                  floorScreenX(fpreal sx) const
                            { return (int)SYSfloor((sx-myXMin)*myIXSinc); }
    int                  ceilScreenX(fpreal sx) const
                            { return (int)SYSceil((sx-myXMin)*myIXSinc); }

    fpreal               computeWeight(float vtx[][2], int nvtx) const;

    // clipOneEdge returns the filter weight for a single edge clip
    fpreal               clipOneEdge(fpreal xl, fpreal xr, fpreal yb, fpreal yt,
                                     const UT_prEdge &edge) const;
    float                        myXSinc, myIXSinc;
    float                        myYSinc, myIYSinc;
    float                        myBoxWeight;
#if 0
    UT_FilterSample             *mySampleTable;
#endif
};

#endif

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