OpenSceneGraph/examples/osgrobot/osgrobot.cpp

/* OpenSceneGraph example, osgrobot.cpp.
*
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*
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*  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
*  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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*/

/* 
    The code below is to show how a hierarchy of objects can be made within a scenegraph.
    In other words, how there can be a parent/child relationship between objects such
    that when a parent is rotated or translated, the children move is respect to it's
    parent movement.  A robotic arm is used in this example because this is what I'm
    using OSG for.
 
    To rotate the joints use the following table to rotate each respective joint.
 
    joint    key        rotation
    1        q        + 1 degree
    1        a        - 1 degree
    2        w        + 1 degree
    2        s        - 1 degree
    3        e        + 1 degree
    3        d        - 1 degree
    4        r        + 1 degree
    4        f        - 1 degree
    5        t        + 1 degree
    5        g        - 1 degree
    6        y        + 1 degree
    6        h        - 1 degree
  
    In many robotics projects, the x and z axis are only used to define the positions
    of the joints of a robotic arm.  By not using the y-axis, the mathematics of
    inverse kinematics becomes easier (and in some cases possible).  All joint rotations
    are rotated about the z-axis.  If you toggle the variable 'showAxis' to true, an
    x (color red), y (color green), and z (color blue) axis will display.  Using the
    thumb of the right hand to point in the same direction of the z-axis, use the right
    hand rule to define a positive angle of rotation.
 
    The robotic arm in general follows the algorithm
    rotate about the x axis, translate along the x-axis, translate along the z axis,
    and then rotate about the z-axis. There is 1 exception in the method buildJoint3(...)
    where it was necessary to add a 'cheat' to get the joints to align properly.  In a
    real robotics project such as this, the tube (see buildTube2(...) method) would not
    be a part of the mathematics and thus, not have to be drawn and would not require
    the cheat.  To learn moue about positioning joints using only the x and z axis,
    web search 'Denavit-Hartenberg'.  wikipedia has comments at the URL...
    http://en.wikipedia.org/wiki/Robotics_conventions#Denavit-Hartenberg_link_frame_convention_.28DH.29
 
    Lessons learned with osg...
    When starting this work I was very new to OSG.  When I first placed a cylinder
    in a scene and rotated the cylinder about the z and x axis, I noticed that the rotation
    is about the barycenter of the object for both axis.  I wanted a rotation about the z-axis
    to be along the length of the tube (which OSG gives for free -- not always true with
    all scenegraphs) while the rotation about the x and y axis about the
    beginning (or start position) of the tube.  Knowing what I know about barycenters
    I positioned the shape along the -height/2 (see example 1 below)
    -- believing the offset -height/2 would place the axis of rotation at the start of
    the tube.  I was certainly wrong about this and found out the equation needs to
    be height/2.
 
    ...
    example 1
    joint->addDrawable(new osg::ShapeDrawable(new osg::Capsule(osg::Vec3(0.0f,0.0f,height/2),radius,height),hints));
    ...
    
 
 
    author: James Moliere
    date written: 10/12/2008
*/

#include <osg/Geode>
#include <osg/ShapeDrawable>
#include <osg/Material>
#include <osg/Texture2D>

#include <osgViewer/Viewer>
#include <iostream>
#include <osgDB/ReadFile>
#include <osg/Math>
#include <osg/Matrixd>
#include <osg/MatrixTransform>
#include <osg/Vec3d>
#include <iostream>
#include <osg/PositionAttitudeTransform>



float jointAngle1;
float jointAngle2;
float jointAngle3;
float jointAngle4;
float jointAngle5;
float jointAngle6;
float EndEffector;

void createAxis(osg::Transform* previousJoint);

osg::MatrixTransform* joint1;
osg::MatrixTransform* joint2;
osg::MatrixTransform* joint3;
osg::MatrixTransform* joint4;
osg::MatrixTransform* joint5;
osg::MatrixTransform* joint6;

osg::MatrixTransform* buildJoint1(osg::MatrixTransform* previousJoint);
osg::MatrixTransform* buildJoint2(osg::MatrixTransform* previousJoint);
osg::MatrixTransform* buildTube2(osg::MatrixTransform* previousJoint);
osg::MatrixTransform* buildJoint3(osg::MatrixTransform* previousJoint);
osg::MatrixTransform* buildJoint4(osg::MatrixTransform* previousJoint);
osg::MatrixTransform* buildTube5(osg::MatrixTransform* previousJoint);
osg::MatrixTransform* buildJoint5(osg::MatrixTransform* previousJoint);
osg::MatrixTransform* buildJoint6(osg::MatrixTransform* previousJoint);
osg::MatrixTransform* buildEndEffector();
osg::TessellationHints* hints = new osg::TessellationHints;

bool showAxis;

class KeyboardEventHandler : public osgGA::GUIEventHandler
{
public:

    KeyboardEventHandler()
    {}


    static void rotate(float angle,osg::MatrixTransform *joint)
    {
        osg::Matrix zRot;
        zRot.makeRotate(angle, 0.0,0.0,1.0);
        joint->setMatrix(zRot*joint->getMatrix());
    }

    virtual bool handle(const osgGA::GUIEventAdapter& ea,osgGA::GUIActionAdapter&)
    {
        switch (ea.getEventType())
        {
        case(osgGA::GUIEventAdapter::KEYDOWN):
            {
                switch (ea.getKey())
                {
                case 'q':
                    rotate(osg::PI/180, joint1); 
                    return true;
                case 'a':
                    rotate(-osg::PI/180, joint1); 
                    return true;
                case 'w':
                    rotate(osg::PI/180, joint2); 
                    return true;
                case 's':
                    rotate(-osg::PI/180, joint2); 
                    return true;
                case 'e':
                    rotate(osg::PI/180, joint3); 
                    return true;
                case 'd':
                    rotate(-osg::PI/180, joint3); 
                    return true;
                case 'r':
                    rotate(osg::PI/180, joint4); 
                    return true;
                case 'f':
                    rotate(-osg::PI/180, joint4); 
                    return true;
                case 't':
                    rotate(osg::PI/180, joint5); 
                    return true;
                case 'g':
                    rotate(-osg::PI/180, joint5); 
                    return true;
                case 'y':
                    rotate(osg::PI/180, joint6); 
                    return true;
                case 'h':
                    rotate(-osg::PI/180, joint6); 
                    return true;
                }
            }
        default:
            break;

        }
        //return false to allow mouse manipulation
        return false;
    }
};


osg::Group* createShapes()
{
    osg::Group* group = new osg::Group();
    osg::MatrixTransform* transform =new osg::MatrixTransform();
    group->addChild(transform);

    joint1 = buildJoint1(transform);
    joint2 = buildJoint2(joint1);
    osg::MatrixTransform* tube2= buildTube2(joint2);
    joint3 = buildJoint3(tube2);
    joint4 = buildJoint4(joint3);
    osg::MatrixTransform *tube5 = buildTube5(joint4);
    joint5 = buildJoint5(tube5);
    joint6= buildJoint6(joint5);
    joint6->addChild( buildEndEffector());
    return group;
}

osg::MatrixTransform* buildJoint1(osg::MatrixTransform* previousJoint)
{
    osg::MatrixTransform* xTransform =new osg::MatrixTransform();
    previousJoint->addChild(xTransform);
    float radius = 6.7640f;
    float height = 45.0f;
    osg::Geode* joint = new osg::Geode();
    xTransform->addChild(joint);
    joint->addDrawable(new osg::ShapeDrawable(new osg::Cylinder(osg::Vec3(0.0f,0.0f,height/2),radius,height),hints));

    osg::MatrixTransform *zTransform = new osg::MatrixTransform();
    xTransform->addChild(zTransform);
    osg::Matrix zTrans=osg::Matrix::translate(0.0, 0.0, height);
    osg::Matrix zRot= osg::Matrix::rotate(jointAngle1, 0.0, 0.0, 1.0);
    zTransform->setMatrix(zTrans*zRot);
    return zTransform;
}

osg::MatrixTransform* buildJoint2(osg::MatrixTransform* previousJoint)
{
    if (showAxis)
    {
        createAxis(previousJoint);
    }
    double height = 17.6;
    double radius = 4.45633;
    osg::MatrixTransform* xTransform = new osg::MatrixTransform();
    previousJoint->addChild(xTransform);
    osg::Matrix xRot = osg::Matrix::rotate(osg::PI_2, 1.0, 0.0, 0.0);
    xTransform->setMatrix(xRot);
    osg::Geode* joint = new osg::Geode();
    joint->addDrawable(new osg::ShapeDrawable(new osg::Capsule(osg::Vec3(0.0f,0.0f,height/2),radius,height),hints));
    xTransform->addChild(joint);

    osg::MatrixTransform* zTransform = new osg::MatrixTransform();
    osg::Matrix zTrans = osg::Matrix::translate( 0.0, 0.0, height);
    osg::Matrix zRot = osg::Matrix::rotate(osg::PI_2+jointAngle2, 0.0,0.0,1.0);
    zTransform->setMatrix(zTrans*zRot);
    xTransform->addChild(zTransform);
    return zTransform;
}

osg::MatrixTransform* buildTube2(osg::MatrixTransform* previousJoint)
{
    if (showAxis)
    {
        createAxis(previousJoint);
    }
    double height = 17.6;
    double radius = 4.45633;
    osg::MatrixTransform* xTransform = new osg::MatrixTransform();
    previousJoint->addChild(xTransform);
    osg::Matrix xRot = osg::Matrix::rotate(osg::PI_2, 1.0,0.0,0.0);
    xTransform->setMatrix(xRot);
    osg::Geode* tube3 = new osg::Geode();
    xTransform->addChild(tube3);
    tube3->addDrawable(new osg::ShapeDrawable(new osg::Capsule(osg::Vec3(0.0f,0.0f,height/2),radius,height),hints));

    osg::MatrixTransform* zTransform = new osg::MatrixTransform();
    xTransform->addChild(zTransform);
    osg::Matrix zTrans = osg::Matrix::translate(0,0,height);
    zTransform->setMatrix(zTrans);
    return zTransform;
}

osg::MatrixTransform* buildJoint3(osg::MatrixTransform* previousJoint)
{
    double height =7.5;
    double radius = 4.45633;
    osg::Geode* joint = new osg::Geode();
    osg::MatrixTransform* xTransform = new osg::MatrixTransform();
    previousJoint->addChild(xTransform);
    osg::Matrix xRot = osg::Matrix::rotate(-osg::PI_2, 1.0, 0.0, 0.0);
    xTransform->setMatrix(xRot);


    osg::MatrixTransform* zCheat = new osg::MatrixTransform();
    osg::Matrix zTransCheat = osg::Matrix::translate(0.0,0.0,-height);
    zCheat->setMatrix(zTransCheat);
    xTransform->addChild(zCheat);
    
    osg::ShapeDrawable *shape = new osg::ShapeDrawable(new osg::Capsule(osg::Vec3(0.0f,0.0f,height/2),radius,height),hints);
    joint->addDrawable(shape);
    zCheat->addChild(joint);

    osg::MatrixTransform* zTransform = new osg::MatrixTransform();
    zCheat->addChild(zTransform);
    osg::Matrix zRot = osg::Matrix::rotate((float)jointAngle3, 0.0f, 0.0f, 1.0f);
    osg::Matrix zTrans = osg::Matrix::translate(0,0,0);
    zTransform->setMatrix(zTrans*zRot);
    if (showAxis)
    {
        createAxis(zTransform);
    }
    return zTransform;
}
osg::MatrixTransform* buildJoint4(osg::MatrixTransform* previousJoint)
{
    double height = 17.5;
    double radius = 2.86479;
    osg::Geode* tube4 = new osg::Geode();
    tube4->addDrawable(new osg::ShapeDrawable(new osg::Capsule(osg::Vec3(0.0f,0.0f,height/2),radius,height),hints));
    osg::MatrixTransform* xTransform = new osg::MatrixTransform();
    //if (showAxis)
    //{
        //createAxis(xTransform);
    //}
    previousJoint->addChild(xTransform);
    xTransform->addChild(tube4);
    osg::Matrix xRot= osg::Matrix::rotate(osg::PI_2, 1,0,0);
    xTransform->setMatrix(xRot);
    height = 7.5;
    osg::Matrix zTrans = osg::Matrix::translate(0,0,17.5);
    osg::Matrix zRot = osg::Matrix::rotate(jointAngle4-osg::PI_2, 0,0,1);

    osg::MatrixTransform* zTransform = new osg::MatrixTransform();
    zTransform->setMatrix(zTrans*zRot);
    xTransform->addChild(zTransform);
    return zTransform;
}


osg::MatrixTransform* buildTube5(osg::MatrixTransform* previousJoint)
{
    if (showAxis)
    {
        createAxis(previousJoint);
    }
    double height = 7.5;
    double radius = 2.86479;

    height = 15.0;
    osg::Geode* joint = new osg::Geode();
    osg::ShapeDrawable *shape =new osg::ShapeDrawable(new osg::Cylinder(osg::Vec3(0.0f,0.0f,height/2),radius,height),hints);
    joint->addDrawable(shape);
    osg::MatrixTransform* xTransform = new osg::MatrixTransform();
    previousJoint->addChild(xTransform);
    xTransform->addChild(joint);

    osg::MatrixTransform* zTransform = new osg::MatrixTransform();
    osg::Matrix zTrans = osg::Matrix::translate(0,0,height);
    zTransform->setMatrix(zTrans);
    xTransform->addChild(zTransform);
    return zTransform;
}

osg::MatrixTransform* buildJoint5(osg::MatrixTransform* previousJoint)
{
    double radius = 2.86479;
    double height = 2.86479*2;
    osg::Geode* joint = new osg::Geode();
    osg::ShapeDrawable *shape = new osg::ShapeDrawable(new osg::Cylinder(osg::Vec3(0.0f,0.0f,0.0f),radius,height),hints);
    joint->addDrawable(shape);
    osg::MatrixTransform* xTransform = new osg::MatrixTransform();
    previousJoint->addChild(xTransform);
    osg::Matrix xRot= osg::Matrix::rotate(-osg::PI_2, 1.0,0,0);
    xTransform->setMatrix(xRot);
    xTransform->addChild(joint);
    if (showAxis)
    {
        createAxis(xTransform);
    }

    osg::MatrixTransform* zTransform = new osg::MatrixTransform();
    osg::Matrix zRot= osg::Matrix::rotate(jointAngle5, 0,0,1);
    osg::Matrix zTrans = osg::Matrix::translate(0,0,0);
    zTransform->setMatrix(zTrans*zRot);
    xTransform->addChild(zTransform);
    return zTransform;
}

osg::MatrixTransform* buildJoint6(osg::MatrixTransform* previousJoint)
{
    double height = 3.0;
    double radius = 1.0;
    osg::Geode* joint = new osg::Geode();
    joint->addDrawable(new osg::ShapeDrawable(new osg::Cylinder(osg::Vec3(0.0f,0.0f,height/2),radius,height),hints));
    osg::MatrixTransform* xTransform = new osg::MatrixTransform();
    osg::Matrix xRot= osg::Matrix::rotate(osg::PI_2, 1.0, 0.0, 0.0);
    xTransform->setMatrix(xRot);
    xTransform->addChild(joint);
    previousJoint->addChild(xTransform);
    if (showAxis)
    {
        createAxis(xTransform);
    }
    return xTransform;
}

osg::MatrixTransform* buildEndEffector()
{
    osg::MatrixTransform* mt = new osg::MatrixTransform();
    osg::Matrix m;
    double length = 17.0;
    m.makeTranslate(0,0,length/2);
    mt->setMatrix(m);
    osg::Geode *geode_3 = new osg::Geode;
    osg::ShapeDrawable *shape1 = new osg::ShapeDrawable(new osg::Box(osg::Vec3(-EndEffector, 0.0f, 0.0f), .5, 1.5f, length), hints);
    osg::ShapeDrawable *shape2 = new osg::ShapeDrawable(new osg::Box(osg::Vec3( EndEffector, 0.0f, 0.0f), .5, 1.5f, length), hints);
    shape1->setColor(osg::Vec4(0.8f, 0.8f, 0.4f, 1.0f));
    shape2->setColor(osg::Vec4(0.8f, 0.8f, 0.4f, 1.0f));
    geode_3->addDrawable(shape1);
    geode_3->addDrawable(shape2);
    mt->addChild(geode_3);
    return mt;
}

void createAxis(osg::Transform* previousJoint)
{
    double height = 12.0;
    double radius = .5;

    osg::MatrixTransform* zmt = new osg::MatrixTransform();

    previousJoint->addChild(zmt);
    osg::ShapeDrawable *zShape = new osg::ShapeDrawable(new osg::Cylinder(osg::Vec3(0.0f,0.0f,height/2),radius,height),hints);
    osg::ShapeDrawable *zCone = new osg::ShapeDrawable(new osg::Cone(osg::Vec3(0.0f,0.0f,1.0),radius+1.0,2.0),hints);

    osg::MatrixTransform* zmtCone = new osg::MatrixTransform();
    osg::Geode *zgCone = new osg::Geode;

    zmtCone->setMatrix( osg::Matrix::translate(0.0,0.0,height));
    previousJoint->addChild(zmtCone);

    zShape->setColor(osg::Vec4(0.0f, 0.0f, 1.0f, 1.0f));
    zCone->setColor(osg::Vec4(0.0f, 0.0f, 1.0f, 1.0f));
    osg::Geode *z = new osg::Geode;
    z->addDrawable(zShape);
    zgCone->addDrawable(zCone);
    zmtCone->addChild(zgCone);
    zmt->addChild(z);

    osg::MatrixTransform* mt = new osg::MatrixTransform();
    previousJoint->addChild(mt);

    osg::Matrix xMatrix = osg::Matrix::rotate(-osg::PI_2, 0.0, 1.0, 0.0);
    mt->setMatrix(xMatrix);


    osg::ShapeDrawable *xShape = new osg::ShapeDrawable(new osg::Cylinder(osg::Vec3(0.0f,0.0f,height/2),radius,height),hints);
    xShape->setColor(osg::Vec4(1.0f, 0.0f, 0.0f, 1.0f));
    osg::Geode *x = new osg::Geode;
    x->addDrawable(xShape);
    mt->addChild(x);


    osg::MatrixTransform *yMt = new osg::MatrixTransform();
    previousJoint->addChild(yMt);
    osg::Matrix yMatrix = osg::Matrix::rotate(osg::PI_2, 1.0, 0.0, 0.0);
    yMt->setMatrix(yMatrix);

    osg::ShapeDrawable *yShape = new osg::ShapeDrawable(new osg::Cylinder(osg::Vec3(0.0f,0.0f,height/2),radius,height),hints);
    yShape->setColor(osg::Vec4(0.0f, 1.0f, 0.0f, 1.0f));
    osg::Geode *y = new osg::Geode;
    y->addDrawable(yShape);
    yMt->addChild(y);
}

int main(int, char **)
{
    hints->setDetailRatio(0.5f);
    showAxis = true;
    jointAngle1=0.0;
    jointAngle2=0.0;
    jointAngle3=0.0;
    jointAngle4=0.0;
    jointAngle5=0.0;
    jointAngle6=0.0;
    EndEffector=1.0;
    osgViewer::Viewer viewer;
    viewer.addEventHandler(new KeyboardEventHandler());

    // add model to viewer.
    viewer.setSceneData( createShapes() );
    return viewer.run();
}