IMG_FileIES.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:        IMG_FileIES.h ( IMG Library, C++)
 *
 * COMMENTS:    Class to read/write IES format.  Images loaded from IES
 *              format will show only the candela values, not the angles.
 *              To map from a direction vector to an image pixel
 *              coordinate, use the getEnvCoord() method.  Specification
 *              for this file format are located here:
 *
 * http://www.ltblight.com/English.lproj/LTBLhelp/pages/iesformat.html
 */

#ifndef __IMG_FileIES__
#define __IMG_FileIES__

#include "IMG_API.h"
#include "IMG_File.h"
#include <UT/UT_NonCopyable.h>

class IMG_API IMG_FileIES : public IMG_File
{
public:
     IMG_FileIES();
    ~IMG_FileIES() override;

    UT_NON_COPYABLE(IMG_FileIES)

    static void  registerFormat();

    int          open() override;
    int          readScanline(int y, void *buf) override;
    int          writeScanline(int y, const void *buf) override;

    int          closeFile() override;

    // This operation converts a direction vector to the IES image
    // coordinates based on the angles specified in the file.
    // The angscale scales the direction vector vertical angle.
    void         getEnvCoord(
        const UT_Vector3    &r, 
        float               &u,
        float               &v, 
        float               angscale) const;

    // mode 1: normalize using maximum value in the table (mantra-style)
    // mode 2: normalize to preserve light's energy output
    float        getNormalization(int mode) const { return myScaler[mode]; }
    
    int          getPhotometricType() const { return myHeader.myPhotometricType; }

    int          getXResolution() const { return myXRes; }
    int          getYResolution() const { return myYRes; }
    const float* getXAngles()     const { return myXAngles.data(); }
    const float* getYAngles()     const { return myYAngles.data(); }
    const float* getImageData()   const { return myImageData.data(); }

private:
    // Helper to construct the actual pixel data for filtering.  This
    // method handles the different symmetry types at load time so that
    // image filtering can be performed without seams.
    void         buildImageData();

private:
    struct Header {
        // Line 10
        int     myNLamps;
        float   myLumensPerLamp;
        float   myCandelaMultiplier;
        int     myVerticalAngles;
        int     myHorizontalAngles;
        int     myPhotometricType;
        int     myUnitsType;
        float   myWidth;
        float   myLength;
        float   myHeight;

        // Line 11
        float   myBallastFactor;
        float   myBallastPhotometricFactor;
        float   myInputWatts;
    };

    UT_String           myFormat;
    UT_String           myTilt;
    Header              myHeader;
    UT_FloatArray       myVerticalAngles;
    UT_FloatArray       myHorizontalAngles;
    UT_FloatArray       myData;

    // IES file data processed into an angle-parameterized sphere map
    UT_FloatArray       myXAngles;
    UT_FloatArray       myYAngles;
    UT_FloatArray       myImageData;
    int                 myXRes;
    int                 myYRes;
    float               myScaler[3];
};

#endif