ddsFloatReader.cpp

//-
// ==========================================================================
// Copyright 2020 Autodesk, Inc. All rights reserved.
//
// Use of this software is subject to the terms of the Autodesk
// license agreement provided at the time of installation or download,
// or which otherwise accompanies this software in either electronic
// or hard copy form.
// ==========================================================================
//+

// DESCRIPTION:
// 
// Demonstrates how to write a .dds float file reader using the API.
// In Maya's image reading menu dialogs, you can select *.* to see all images, and
// then retrieve a dds extension file item to load the .dds file into Maya. 
//

#include <maya/MPxImageFile.h>
#include <maya/MImageFileInfo.h>
#include <maya/MImage.h>
#include <maya/MFnPlugin.h>
#include <maya/MStringArray.h>
#include <maya/MIOStream.h>

#if _WIN32   
#pragma warning( disable : 4290 )       // Disable STL warnings.
#endif

#include "ddsFloatReader.h"
#include <math.h>

using namespace dds_Float_Reader;
MString kImageFormatName( "DDS Float");

class ddsFloatReader : public MPxImageFile
{
public:
                    ddsFloatReader();
            ~ddsFloatReader() override;
    static void*    creator();
    MStatus open( MString pathname, MImageFileInfo* info) override;
    MStatus load( MImage& image, unsigned int idx) override;
    MStatus close() override;

protected:
    // Data members 
    unsigned int        fWidth;
    unsigned int        fHeight;
    unsigned int        fNumChannels;
    unsigned int        fBytesPerPixel;

    // File and header description
    FILE                *fInputFile;
    DDS_HEADER          fHeader;
};

//
// DESCRIPTION:
ddsFloatReader::ddsFloatReader()
:   fWidth(0), 
    fHeight(0), 
    fNumChannels(0), 
    fBytesPerPixel(0),
    fInputFile(NULL)
{
}

//
// DESCRIPTION:
ddsFloatReader::~ddsFloatReader()
{
    close();
}


//
// DESCRIPTION:
/* virtual */
MStatus  ddsFloatReader::close()
{
    fWidth = 0;
    fHeight = 0;
    fNumChannels = 0;
    fBytesPerPixel = 0;

    // Close our file
    if (fInputFile != NULL)
        fclose(fInputFile);
    fInputFile = NULL;

    return MS::kSuccess;
}

//
// DESCRIPTION:
void * ddsFloatReader::creator()
{
    return new ddsFloatReader();
}

// Need to swap byte order on Mac
//
inline void swap_endian(void *val)
{
#if defined(__APPLE__)
    unsigned int *ival = (unsigned int *)val;

    *ival = ((*ival >> 24) & 0x000000ff) |
            ((*ival >>  8) & 0x0000ff00) |
            ((*ival <<  8) & 0x00ff0000) |
            ((*ival << 24) & 0xff000000);

#endif
}

inline void swap_endian_half(void *val)
{
#if defined(__APPLE__)
    unsigned short *ival = (unsigned short *)val;

    *ival = ((*ival >> 8) & 255) |
            ((*ival << 8) & 65280);

#endif
}

const double two_pow_neg14 = pow(2.0, -14.0);

//
// Half to float conversion
//
inline float halfToFloat(unsigned short val)
{
    float outValue = 0.0f;


#if defined(__APPLE__)
    // Need to swap bytes on Power PC (Mac)
    swap_endian_half( &val );
#endif

    // Convert 16-value into a float...
    double h_mantissa = (float) (val & 1023); // Mantissa = low order 10  bits
    double h_exponent = (float)  ((val >> 10) & 31); // Exponent = next 5 bits
    unsigned int i_sign = (val >> 15) & 1;  ; // Sign is the highest bit
    double h_sign = (i_sign == 0) ? 1.0 : -1.0;

    if (h_exponent != 30.0)
    {
        outValue = (float) (h_sign * pow(2.0, h_exponent-15.0) * ( 1.0 + ( h_mantissa / 1024.0 )));
    }
    else
    {
        outValue = (float) ( h_sign * pow(2.0, two_pow_neg14) * ( h_mantissa / 1024.0 ) );
    }
    //printf("[%d][%d] = inValue=%d, isign =%d, sign=%g, exp=%g, mant=%g, value=%g\n", y,x, *inPtr, i_sign, h_sign, h_exponent, h_mantissa, outValue);
    return outValue;
}

//
// DESCRIPTION:
MStatus ddsFloatReader::open( MString filename, MImageFileInfo* info)
{   
#if _WIN32   
    if ( ( fInputFile = fopen( filename.asChar(), "rb" ) ) == NULL )
#else
    if ( ( fInputFile = fopen( filename.asChar(), "r" ) ) == NULL )
#endif
    {
        // Unable to open the file
        return MS::kFailure;
    }

    // Read the DDS header in 
    //
    if ( fread( &fHeader, 1, sizeof(DDS_HEADER), fInputFile) == sizeof(DDS_HEADER) )
    {
        swap_endian(&fHeader.fCapabilities.dwCaps2);

        // Cube maps and volume textures are not supported currently.
        //
        if (( (fHeader.fCapabilities.dwCaps2) & DDSCAPS2_CUBEMAP_FLAG ) ||
            ( (fHeader.fCapabilities.dwCaps2) & DDSCAPS2_VOLUME_FLAG ))
        {
            close();
            return MS::kFailure;
        }

        // Get dimensions of image
        //
        swap_endian(&fHeader.fWidth);
        swap_endian(&fHeader.fHeight);
        fWidth = fHeader.fWidth;
        fHeight = fHeader.fHeight;
        fNumChannels = 0;

        if (fWidth==0 || fHeight==0)
        {
            close();
            return MS::kFailure;
        }


        // Check for float formats
        //
        swap_endian(& fHeader.fFormat.fFlags );
        if (fHeader.fFormat.fFlags & DDS_FOURCC_FLAG)
        {
            swap_endian(&fHeader.fFormat.fPixelFormat);

            bool supportedFormat = true;

            // Half float formats
            switch (fHeader.fFormat.fPixelFormat)
            {

            // Half float formats 
            //
            case DDS_R16F:
                fNumChannels = 1;
                fBytesPerPixel = 2; // 16-bits
                break;
            case DDS_G16R16F:
                fNumChannels = 2;
                fBytesPerPixel = 4; // 32-bits
                break;
            case DDS_A16B16G16R16F:
                fNumChannels = 4;
                fBytesPerPixel = 8; // 64-bits
                break;

            // IEEE 32 bit formats
            case DDS_R32F:
                fNumChannels = 1;
                fBytesPerPixel = 4; // 32-bits
                break;
            case DDS_G32R32F:
                fNumChannels = 2;
                fBytesPerPixel = 8; // 64-bits
                break;
            case DDS_A32B32G32R32F:
                fNumChannels = 4;
                fBytesPerPixel = 16; // 128-bits
                break;

            // Anything else is not supported
            default:
                supportedFormat = false;
                break;
            }

            if (!supportedFormat)
            {
                close();
                return MS::kFailure;
            }
        }
        else
        {
            close();
            return MS::kFailure;
        }

        // Return image information based on the header
        //
        if (info)
        {
            //printf("** Opened DDS: %s (w=%d,h=%d, fmt=%d)\n",
            //  filename.asChar(),
            //  fWidth,
            //  fHeight,
            //  fHeader.fFormat.fPixelFormat);

            // Only read in 1 image for now
            info->numberOfImages( 1 );
            info->width( fWidth );
            info->height( fHeight );
            info->channels( fNumChannels );
            info->hasAlpha( fNumChannels == 4 );

            // Mip maps not handled for now
            info->hasMipMaps( false );

            info->imageType( MImageFileInfo::kImageTypeColor );
            info->hardwareType( MImageFileInfo::kHwTexture2D );
            info->pixelType( MImage::kFloat ); 
        }
    }
    return MS::kSuccess;
}


//
// DESCRIPTION:
MStatus ddsFloatReader::load( MImage& image, unsigned int imageNumber)
{
    MStatus loaded = MS::kFailure;

    // Check for half type, since we need to perform
    // some special bit conversions to get a float back.
    //
    bool isHalfType = false;
    switch (fHeader.fFormat.fPixelFormat)
    {
    case DDS_R16F:
        isHalfType = true;
        break;
    case DDS_G16R16F:
        isHalfType = true;
        break;
    case DDS_A16B16G16R16F:
        isHalfType = true;
        break;
    default:
        break;
    }   

    // Create the output buffer
    //
    image.create( fWidth, fHeight, fNumChannels, MImage::kFloat);
    float* outputBuffer = image.floatPixels();

    // Create the input buffer to read one scanline at a time.
    //
    float *inputFloatBuffer = NULL;         // For IEEE float
    unsigned short *inputIntBuffer = NULL;  // For half-float = 16-bits per channel
    if (!isHalfType)
    {
        inputFloatBuffer = new float[fWidth * fNumChannels];
    }
    else
        inputIntBuffer= new unsigned short[fWidth * fNumChannels];

    // Can't get sufficient memory so fail and close up the
    // file.
    if ((!inputFloatBuffer && !inputIntBuffer) || !outputBuffer)
    {
        if (inputFloatBuffer)
        {
            delete [] inputFloatBuffer;
            inputFloatBuffer = NULL;
        }
        if (inputIntBuffer)
        {
            delete [] inputIntBuffer;
            inputIntBuffer = NULL;
        }
        close();
        return MS::kFailure;
    }

    // Transfer to output buffer.
    //
    if (isHalfType) 
    {
        unsigned int x,y;
        float *outPtr = outputBuffer;

        // Do a scanline at a time. From top-to-bottom
        // so that scan lines are flipped for Maya's usage.
        //
        outPtr += (fHeight-1) * (fWidth * fNumChannels);

        for (y=0; y<fHeight; y++)
        {
            // Read in one scan line of data
            unsigned int numBytes = fWidth * fBytesPerPixel;
            fread( inputIntBuffer, 1, numBytes, fInputFile);
            
            unsigned short *inPtr = inputIntBuffer;

            for (x=0; x<fWidth * fNumChannels; x++)
            {
                float outValue = halfToFloat(*inPtr);
                *(outPtr + x) = outValue;
                inPtr++; // Jump 2 bytes at a time = 1 channel
            }
            outPtr -= (fWidth * fNumChannels);
        }
        loaded = MS::kSuccess;
    }
    
    // IEEE 32-bit float
    else 
    {
        unsigned int x,y;
        float *outPtr = outputBuffer;

        // Do a scanline at a time. From top-to-bottom
        // so that scan lines are flipped for Maya's usage.
        //
        outPtr += (fHeight-1) * (fWidth * fNumChannels);

        for (y=0; y<fHeight; y++)
        {
            // Read in one scan line of data
            unsigned int numBytes = fWidth * fBytesPerPixel;
            fread( inputFloatBuffer, 1, numBytes, fInputFile);
            
#if defined(__APPLE__)
            // Need to swap bytes on Power PC (Mac)
            unsigned int *bPtr = (unsigned int *)inputFloatBuffer;
            unsigned int b;
            for (b=0; b<numBytes / 4; b++)
            {
                swap_endian( bPtr );
                bPtr++;
            }
#endif
            float *inPtr = inputFloatBuffer;
            for (x=0; x<fWidth * fNumChannels; x++)
            {
                *(outPtr + x) = *inPtr;
                inPtr++;
            }
            outPtr -= (fWidth * fNumChannels);
        }
        loaded = MS::kSuccess;
    }

    // Cleanup memory and close the file
    if (inputFloatBuffer)
    {
        delete [] inputFloatBuffer;
        inputFloatBuffer = NULL;
    }
    if (inputIntBuffer)
    {
        delete [] inputFloatBuffer;
        inputFloatBuffer = NULL;
    }
    close();

    return loaded;
}


MStatus initializePlugin( MObject obj )
{
    MFnPlugin plugin( obj, PLUGIN_COMPANY, "2020", "Any" );
    MStringArray extensions;
    extensions.append( "dds");

    // This plugin is registered with a low priority. That means
    // this plugin will only be use if Maya is not able the load a DDS file
    // from a plugin with higher priority or by it internal code.
    CHECK_MSTATUS( plugin.registerImageFile( 
                    kImageFormatName,
                    ddsFloatReader::creator,       
                    extensions,
                    MFnPlugin::kImageFilePriorityLow));
    
    return MS::kSuccess;
}

// DESCRIPTION:
MStatus uninitializePlugin( MObject obj )
{
    MFnPlugin plugin( obj );
    CHECK_MSTATUS( plugin.deregisterImageFile( kImageFormatName ) );

    return MS::kSuccess;
}