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| #include <osg/Node>
#include <osg/Group>
#include <osg/Geode>
#include <osg/Geometry>
#include <osg/Texture2D>
#include <osgDB/ReadFile>
#include <osgViewer/Viewer>
#include <osg/PositionAttitudeTransform>
#include <osgGA/TrackballManipulator>
int main()
{
osgViewer::Viewer viewer;
osg::Group* root = new osg::Group();
osg::Geode* pyramidGeode = new osg::Geode();
osg::Geometry* pyramidGeometry = new osg::Geometry();
osg::Geode* crossGeode = new osg::Geode();
osg::Geometry* crossGeometry = new osg::Geometry();
//Associate the pyramid geometry with the pyramid geode
// Add the pyramid geode to the root node of the scene graph.
pyramidGeode->addDrawable(pyramidGeometry);
root->addChild(pyramidGeode);
crossGeode->addDrawable(crossGeometry);
root->addChild(crossGeode);
//Declare an array of vertices. Each vertex will be represented by
//a triple -- an instances of the vec3 class. An instance of
//osg::Vec3Array can be used to store these triples. Since
//osg::Vec3Array is derived from the STL vector class, we can use the
//push_back method to add array elements. Push back adds elements to
//the end of the vector, thus the index of first element entered is
//zero, the second entries index is 1, etc.
//Using a right-handed coordinate system with 'z' up, array
//elements zero..four below represent the 5 points required to create
//a simple pyramid.
osg::Vec3Array* pyramidVertices = new osg::Vec3Array;
pyramidVertices->push_back( osg::Vec3( 0, 0, 0) ); // front left
pyramidVertices->push_back( osg::Vec3(10, 0, 0) ); // front right
pyramidVertices->push_back( osg::Vec3(10,10, 0) ); // back right
pyramidVertices->push_back( osg::Vec3( 0,10, 0) ); // back left
pyramidVertices->push_back( osg::Vec3( 5, 5,10) ); // peak
float clen;
clen = 12.0;
osg::Vec3Array* crossVertices = new osg::Vec3Array;
crossVertices->push_back (osg::Vec3(-clen, 0.0, 0.0));
crossVertices->push_back (osg::Vec3( clen, 0.0, 0.0));
crossVertices->push_back (osg::Vec3( 0.0, 0.0, -clen));
crossVertices->push_back (osg::Vec3( 0.0, 0.0, clen));
//Associate this set of vertices with the geometry associated with the
//geode we added to the scene.
pyramidGeometry->setVertexArray( pyramidVertices );
crossGeometry->setVertexArray (crossVertices);
//Next, create a primitive set and add it to the pyramid geometry.
//Use the first four points of the pyramid to define the base using an
//instance of the DrawElementsUint class. Again this class is derived
//from the STL vector, so the push_back method will add elements in
//sequential order. To ensure proper backface cullling, vertices
//should be specified in counterclockwise order. The arguments for the
//constructor are the enumerated type for the primitive
//(same as the OpenGL primitive enumerated types), and the index in
//the vertex array to start from.
osg::DrawElementsUInt* pyramidBase =
new osg::DrawElementsUInt(osg::PrimitiveSet::QUADS, 0);
pyramidBase->push_back(3);
pyramidBase->push_back(2);
pyramidBase->push_back(1);
pyramidBase->push_back(0);
pyramidGeometry->addPrimitiveSet(pyramidBase);
osg::DrawElementsUInt* cross =
new osg::DrawElementsUInt(osg::PrimitiveSet::LINES, 0);
cross->push_back(3);
cross->push_back(2);
cross->push_back(1);
cross->push_back(0);
crossGeometry->addPrimitiveSet(cross);
//Repeat the same for each of the four sides. Again, vertices are
//specified in counter-clockwise order.
osg::DrawElementsUInt* pyramidFaceOne =
new osg::DrawElementsUInt(osg::PrimitiveSet::TRIANGLES, 0);
pyramidFaceOne->push_back(0);
pyramidFaceOne->push_back(1);
pyramidFaceOne->push_back(4);
pyramidGeometry->addPrimitiveSet(pyramidFaceOne);
osg::DrawElementsUInt* pyramidFaceTwo =
new osg::DrawElementsUInt(osg::PrimitiveSet::TRIANGLES, 0);
pyramidFaceTwo->push_back(1);
pyramidFaceTwo->push_back(2);
pyramidFaceTwo->push_back(4);
pyramidGeometry->addPrimitiveSet(pyramidFaceTwo);
osg::DrawElementsUInt* pyramidFaceThree =
new osg::DrawElementsUInt(osg::PrimitiveSet::TRIANGLES, 0);
pyramidFaceThree->push_back(2);
pyramidFaceThree->push_back(3);
pyramidFaceThree->push_back(4);
pyramidGeometry->addPrimitiveSet(pyramidFaceThree);
osg::DrawElementsUInt* pyramidFaceFour =
new osg::DrawElementsUInt(osg::PrimitiveSet::TRIANGLES, 0);
pyramidFaceFour->push_back(3);
pyramidFaceFour->push_back(0);
pyramidFaceFour->push_back(4);
pyramidGeometry->addPrimitiveSet(pyramidFaceFour);
//Declare and load an array of Vec4 elements to store colors.
osg::Vec4Array* colors = new osg::Vec4Array;
colors->push_back(osg::Vec4(1.0f, 0.0f, 0.0f, 1.0f) ); //index 0 red
colors->push_back(osg::Vec4(0.0f, 1.0f, 0.0f, 1.0f) ); //index 1 green
colors->push_back(osg::Vec4(0.0f, 0.0f, 1.0f, 1.0f) ); //index 2 blue
colors->push_back(osg::Vec4(1.0f, 1.0f, 1.0f, 1.0f) ); //index 3 white
//Declare the variable that will match vertex array elements to color
//array elements. This vector should have the same number of elements
//as the number of vertices. This vector serves as a link between
//vertex arrays and color arrays. Entries in this index array
//coorespond to elements in the vertex array. Their values coorespond
//to the index in he color array. This same scheme would be followed
//if vertex array elements were matched with normal or texture
//coordinate arrays.
// Note that in this case, we are assigning 5 vertices to four
// colors. Vertex array element zero (bottom left) and four (peak)
// are both assigned to color array element zero (red).
osg::TemplateIndexArray
<unsigned int, osg::Array::UIntArrayType,4,4> *colorIndexArray;
colorIndexArray =
new osg::TemplateIndexArray<unsigned int, osg::Array::UIntArrayType,4,4>;
colorIndexArray->push_back(0); // vertex 0 assigned color array element 0
colorIndexArray->push_back(1); // vertex 1 assigned color array element 1
colorIndexArray->push_back(2); // vertex 2 assigned color array element 2
colorIndexArray->push_back(3); // vertex 3 assigned color array element 3
colorIndexArray->push_back(0); // vertex 4 assigned color array element 0
//The next step is to associate the array of colors with the geometry,
//assign the color indices created above to the geometry and set the
//binding mode to _PER_VERTEX.
pyramidGeometry->setColorArray(colors);
pyramidGeometry->setColorIndices(colorIndexArray);
pyramidGeometry->setColorBinding(osg::Geometry::BIND_PER_VERTEX);
crossGeometry->setColorArray(colors);
crossGeometry->setColorIndices(colorIndexArray);
crossGeometry->setColorBinding(osg::Geometry::BIND_PER_VERTEX);
//Now that we have created a geometry node and added it to the scene
//we can reuse this geometry. For example, if we wanted to put a
//second pyramid 15 units to the right of the first one, we could add
//this geode as the child of a transform node in our scene graph.
// Declare and initialize a transform node.
osg::PositionAttitudeTransform* pyramidTwoXForm =
new osg::PositionAttitudeTransform();
// Use the 'addChild' method of the osg::Group class to
// add the transform as a child of the root node and the
// pyramid node as a child of the transform.
root->addChild(pyramidTwoXForm);
pyramidTwoXForm->addChild(pyramidGeode);
// Declare and initialize a Vec3 instance to change the
// position of the model in the scene
osg::Vec3 pyramidTwoPosition(15,0,0);
pyramidTwoXForm->setPosition( pyramidTwoPosition );
//The final step is to set up and enter a simulation loop.
viewer.setSceneData( root );
//viewer.run();
viewer.setCameraManipulator(new osgGA::TrackballManipulator());
viewer.realize();
while( !viewer.done() )
{
viewer.frame();
}
return 0;
} |
