rockingTransform/rockingTransform.cpp

//-
// ==========================================================================
// Copyright 2015 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.
// ==========================================================================
//+

//
// Example custom transform:
//  This plug-in implements an example custom transform that
//  can be used to perform a rocking motion around the X axis.
//  Geometry of any rotation can be made a child of this transform
//  to demonstrate the effect.
//  The plug-in contains two pieces:
//  1. The custom transform node -- rockingTransformNode
//  2. The custom transformation matrix -- rockingTransformMatrix
//  These classes are used together in order to implement the
//  rocking motion.  Note that the rock attribute is stored outside
//  of the regular transform attributes.
//
// MEL usage:
/*
    // Create a rocking transform and make a rotated plane
    // its child.
    loadPlugin rockingTransform;
    file -f -new;
    polyPlane -w 1 -h 1 -sx 10 -sy 10 -ax 0 1 0 -cuv 2 -ch 1;
    select -r pPlane1 ;
    rotate -r -ws -15 -15 -15 ;
    createNode rockingTransform;
    parent pPlane1 rockingTransform1;
    setAttr rockingTransform1.rockx 55;
*/
//

#include <maya/MPxTransform.h>
#include <maya/MPxTransformationMatrix.h>
#include <maya/MGlobal.h>
#include <maya/MFnNumericAttribute.h>
#include <maya/MTransformationMatrix.h>
#include <maya/MIOStream.h>
#include <assert.h>

#include "rockingTransform.h"

#ifndef M_PI
#include <math.h>
#endif

//
// Initialize our static class variables
//
MObject rockingTransformNode::aRockInX;
MTypeId rockingTransformNode::id(kRockingTransformNodeID);
MTypeId rockingTransformMatrix::id(kRockingTransformMatrixID);

//
// Implementation of our custom transformation matrix
//

//
//  Constructor for matrix
//
rockingTransformMatrix::rockingTransformMatrix()
{
    rockXValue = 0.0;
}

//
// Creator for matrix
//
MPxTransformationMatrix *rockingTransformMatrix::creator()
{
    return new rockingTransformMatrix();
}

//
//  Utility method for getting the rock
//  motion in the X axis
//
double rockingTransformMatrix::getRockInX() const
{
    return rockXValue;
}

//
//  Utility method for setting the rock
//  motion in the X axis
//
void rockingTransformMatrix::setRockInX( double rock )
{
    rockXValue = rock;
}

//
// This method will be used to return information to
// Maya.  Use the attributes which are outside of
// the regular transform attributes to build a new
// matrix.  This new matrix will be passed back to
// Maya.
//
MMatrix rockingTransformMatrix::asMatrix() const
{
    // Get the current transform matrix
    MMatrix m = ParentClass::asMatrix();
    // Initialize the new matrix we will calculate
    MTransformationMatrix tm( m );
    // Find the current rotation as a quaternion
    MQuaternion quat = rotation();
    // Convert the rocking value in degrees to radians
    DegreeRadianConverter conv;
    double newTheta = conv.degreesToRadians( getRockInX() );
    quat.setToXAxis( newTheta );
    // Apply the rocking rotation to the existing rotation
    tm.addRotationQuaternion( quat.x, quat.y, quat.z, quat.w, MSpace::kTransform );
    // Let Maya know what the matrix should be
    return tm.asMatrix();
}

MMatrix rockingTransformMatrix::asMatrix(double percent) const
{
    MPxTransformationMatrix m(*this);

    //  Apply the percentage to the matrix components
    MVector trans = m.translation();
    trans *= percent;
    m.translateTo( trans );
    MPoint rotatePivotTrans = m.rotatePivot();
    rotatePivotTrans = rotatePivotTrans * percent;
    m.setRotatePivot( rotatePivotTrans );
    MPoint scalePivotTrans = m.scalePivotTranslation();
    scalePivotTrans = scalePivotTrans * percent;
    m.setScalePivotTranslation( scalePivotTrans );

    //  Apply the percentage to the rotate value.  Same
    // as above + the percentage gets applied
    MQuaternion quat = rotation();
    DegreeRadianConverter conv;
    double newTheta = conv.degreesToRadians( getRockInX() );
    quat.setToXAxis( newTheta );
    m.rotateBy( quat );
    MEulerRotation eulRotate = m.eulerRotation();
    m.rotateTo(  eulRotate * percent, MSpace::kTransform);

    //  Apply the percentage to the scale
    MVector s(scale(MSpace::kTransform));
    s.x = 1.0 + (s.x - 1.0)*percent;
    s.y = 1.0 + (s.y - 1.0)*percent;
    s.z = 1.0 + (s.z - 1.0)*percent;
    m.scaleTo(s, MSpace::kTransform);

    return m.asMatrix();
}

MMatrix rockingTransformMatrix::asRotateMatrix() const
{
    // To be implemented
    return ParentClass::asRotateMatrix();
}


//
// Implementation of our custom transform
//

//
//  Constructor of the transform node
//
rockingTransformNode::rockingTransformNode()
: ParentClass()
{
}

//
//  Post constructor method.  Have access to *this.  Node setup
//  operations that do not go into the initialize() method should go
//  here.
//
void rockingTransformNode::postConstructor()
{
    //  Make sure the parent takes care of anything it needs.
    //
    ParentClass::postConstructor();

    MPlug aRockInXPlug(thisMObject(), aRockInX);
}

//
//  This method computes the transformation matrix for a passed data block
//  and places the output into a passed transformation matrix.
//
MStatus
rockingTransformNode::computeLocalTransformation(MPxTransformationMatrix *xform,
                                                 MDataBlock &block)
{
    //  Get the value from the aRockInX attribute
    MStatus status = MS::kSuccess;
    MDataHandle rockInXHandle = block.inputValue (aRockInX, &status);
    ReturnOnError(status);
    
    // Store it in the transformation matrix so that when asked for it through
    // asMatrix() it can construct the desired matrix
    rockingTransformMatrix* ltm = dynamic_cast<rockingTransformMatrix*>(xform);
    assert(ltm);
    ltm->setRockInX(rockInXHandle.asDouble());

    return ParentClass::computeLocalTransformation(xform, block);
}

//
//  The transform's compute method
//
MStatus rockingTransformNode::compute( const MPlug& plug, MDataBlock& block )
{ 
    if( (plug.attribute() == MPxTransform::matrix)
    ||  (plug.attribute() == MPxTransform::inverseMatrix)
    ||  (plug.attribute() == MPxTransform::worldMatrix)
    ||  (plug.attribute() == MPxTransform::worldInverseMatrix)
    ||  (plug.attribute() == MPxTransform::parentMatrix)
    ||  (plug.attribute() == MPxTransform::parentInverseMatrix) )
    {
        rockingTransformMatrix *ltm = getRockingTransformMatrix();
        if (ltm) {
            computeLocalTransformation(ltm, block);
        } else {
            MGlobal::displayError("Failed to get rock transform matrix");
        }
    }

    return MPxTransform::compute(plug, block);
}
//
//  Destructor of the rocking transform
//
rockingTransformNode::~rockingTransformNode()
{
}

//
//  Method that returns the new transformation matrix
//
MPxTransformationMatrix *rockingTransformNode::createTransformationMatrix()
{
    return new rockingTransformMatrix();
}

//
//  Method that returns a new transform node
//
void *rockingTransformNode::creator()
{
    return new rockingTransformNode();
}

//
//  Node initialize method.  We configure node
//  attributes here.  Static method so
//  *this is not available.
//
MStatus rockingTransformNode::initialize()
{
    MFnNumericAttribute numFn;
    aRockInX = numFn.create("RockInX", "rockx", MFnNumericData::kDouble, 0.0);
    numFn.setKeyable(true);
    numFn.setAffectsWorldSpace(true);
    addAttribute(aRockInX);

    // Need to update matrix when attribute aRockInX is modified
    attributeAffects(aRockInX, matrix);

    //  This is required so that the validateAndSet method is called
    mustCallValidateAndSet(aRockInX);
    return MS::kSuccess;
}

//
//  Debugging method
//
const char* rockingTransformNode::className()
{
    return "rockingTransformNode";
}

//
//  Reset transformation
//
void  rockingTransformNode::resetTransformation (const MMatrix &matrix)
{
    ParentClass::resetTransformation( matrix );
}

//
//  Reset transformation
//
void  rockingTransformNode::resetTransformation (MPxTransformationMatrix *resetMatrix )
{
    ParentClass::resetTransformation( resetMatrix );
}

//
// A very simple implementation of validAndSetValue().  No lock
// or limit checking on the rocking attribute is done in this method.
// If you wish to apply locks and limits to the rocking attribute, you
// would follow the approach taken in the rockingTransformCheck example.
// Meaning you would implement methods similar to:
//  * applyRotationLocks();
//  * applyRotationLimits();
//  * checkAndSetRotation();
// but for the rocking attribute.  The method checkAndSetRotation()
// would be called below rather than updating the rocking attribute
// directly.
//
MStatus rockingTransformNode::validateAndSetValue(const MPlug& plug, const MDataHandle& handle)
{
    //  Make sure that there is something interesting to process.
    //
    if (plug.isNull())
        return MS::kFailure;

    if ( plug == aRockInX )
    {
        MStatus status = MS::kSuccess;

        MDataBlock block = forceCache();
        MDataHandle blockHandle = block.outputValue(plug, &status);
        ReturnOnError(status);

        // Update our new rock in x value
        double rockInX = handle.asDouble();
        blockHandle.set(rockInX);

        // Update the custom transformation matrix to the
        // right rock value.
        rockingTransformMatrix *ltm = getRockingTransformMatrix();
        if (ltm)
            ltm->setRockInX(rockInX);
        else
            MGlobal::displayError("Failed to get rock transform matrix");

        blockHandle.setClean();

        // Mark the matrix as dirty so that DG information
        // will update.
        dirtyMatrix();

        return status;
    }

    // Allow processing for other attributes
    return ParentClass::validateAndSetValue(plug, handle);
}

//
//  Method for returning the current rocking transformation matrix
//
rockingTransformMatrix *rockingTransformNode::getRockingTransformMatrix()
{
    rockingTransformMatrix *ltm = (rockingTransformMatrix *) transformationMatrixPtr();
    return ltm;
}

//
// Utility class
//
double DegreeRadianConverter::degreesToRadians( double degrees )
{
     return degrees * ( M_PI/ 180.0 );
}
double DegreeRadianConverter::radiansToDegrees( double radians )
{
    return radians * (180.0/M_PI);
}