customImagePlane/customImagePlane.cpp

//-
// ==========================================================================
// Copyright 2019 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 create your own custom image plane based on
//   Maya's internal image plane classes. This allows API users to
//   override the default Maya image plane behavior. This class works
//   like typical API nodes in that it can have a compute method and
//   can contain static attributes added by the API user.  This
//   example class overrides the default image plane behavior and
//   allows users to add transparency to an image plane using the
//   transparency attribute on the node. Note, this code also 
//   illustrates how to use MImage to control the floating point
//   depth buffer.  When useDepthMap is set to true, depth is added
//   is added to the image such that half of the image is at the near 
//   clip plane and the remaining half is at the far clip plane. 
//
//   Note, once the image plane node has been created it you must
//   attached it to the camera shape that is displaying the node.
//   You need to use the imagePlane command to attach the image plane 
//   you created to the specified camera.
//
//   This example works only with renderers that use node evaluation
//   as a part of the rendering process, e.g. Maya Software. It does 
//   not work with 3rd party renderers that rely on a scene translation 
//   mechanism.
// 
//   For example, 
//     string $imageP = `createNode customImagePlane`;
//     imagePlane -edit -camera "persp" $imageP
//    

#include <maya/MPxImagePlane.h>
#include <maya/MFnPlugin.h>
#include <maya/MImage.h>
#include <maya/MString.h>
#include <maya/MFnNumericAttribute.h> 
#include <maya/MFnNumericData.h> 
#include <maya/MDataHandle.h> 
#include <maya/MPlug.h> 

class customImagePlane : public MPxImagePlane
{
public:
                        customImagePlane();
    MStatus             loadImageMap( const MString &fileName, int frame, MImage &image ) override;

    bool                getInternalValue( const MPlug&, MDataHandle&)       override;
    bool                setInternalValue( const MPlug&, const MDataHandle&) override;

    static  void*       creator();
    static  MStatus     initialize();

    static  MTypeId     id;             // The IFF type id
    static  MObject     aTransparency;

private: 
    double              fTransparency;
};

MObject customImagePlane::aTransparency; 

customImagePlane::customImagePlane()
: MPxImagePlane()
, fTransparency( 0.0 )
{
}

bool
customImagePlane::getInternalValue( const MPlug &plug, MDataHandle &handle)
{
    if ( plug == aTransparency ) {
        handle.set( fTransparency );
        return true; 
    }

    return MPxImagePlane::getInternalValue( plug, handle );
}

bool
customImagePlane::setInternalValue( const MPlug &plug, const MDataHandle &handle)
{
    if ( plug == aTransparency ) {
        fTransparency = handle.asDouble();
        setImageDirty();
        return true;
    }

    return MPxImagePlane::setInternalValue( plug, handle );
}

MStatus
customImagePlane::loadImageMap( const MString &fileName, int frame, MImage &image )
{
    image.readFromFile(fileName);

    unsigned int width, height;
    image.getSize(width, height);
    unsigned int size = width * height; 

    unsigned char *pixels = image.pixels(); 
    unsigned int i; 
    for ( i = 0; i < size; i ++, pixels += 4 ) { 
        pixels[3] = (unsigned char)(pixels[3] * (1.0 - fTransparency));
    }

    MPlug depthMap( thisMObject(), useDepthMap ); 
    bool value; 
    depthMap.getValue( value ); 
    
    if ( value ) {
        float *buffer = new float[width*height];
        unsigned int c, j; 
        for ( c = i = 0; i < height; i ++ ) { 
            for ( j = 0; j < width; j ++, c++ ) { 
                if ( i > height/2 ) { 
                    buffer[c] = -1.0f;
                } else { 
                    buffer[c] = 0.0f;
                }
            }
        }
        image.setDepthMap( buffer, width, height ); 
        delete [] buffer;
    }

    return MStatus::kSuccess;
}

MTypeId customImagePlane::id( 0x1A19 );

void*
customImagePlane::creator()
{
    return new customImagePlane;
}

MStatus
customImagePlane::initialize()
{
    MFnNumericAttribute nAttr; 

    aTransparency = nAttr.create( "transparency", "tp", 
                                  MFnNumericData::kDouble, 0 );
    nAttr.setStorable(true); 
    nAttr.setInternal(true); 
    nAttr.setMin(0.0); 
    nAttr.setMax(1.0); 
    nAttr.setDefault(0.0);
    nAttr.setKeyable(true); 

    addAttribute( aTransparency ); 

    return MStatus::kSuccess;
}

// These methods load and unload the plugin, registerNode registers the
// new node type with maya
//
MStatus initializePlugin( MObject obj )
{
    MFnPlugin plugin( obj, PLUGIN_COMPANY, "7.0", "Any");

    MStatus status = plugin.registerNode( "customImagePlane", customImagePlane::id, 
                                  customImagePlane::creator,
                                  customImagePlane::initialize, 
                                  MPxNode::kImagePlaneNode );
    if (!status) {
        status.perror("registerNode");
    }

    return status;
}

MStatus uninitializePlugin( MObject obj )
{
    MFnPlugin plugin( obj );

    MStatus status = plugin.deregisterNode( customImagePlane::id );
    if (!status) {
        status.perror("deregisterNode");
    }

    return status;
}