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From Mike Garrity, "There was an on again/off again thread on OSG users about

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creating subclasses of osg::Array that referenced data
stored an application's internal data structures. I took
a stab at implementing that and ran into a couple of
downcasts in Geometry.cpp. Enclosed is my take at fixing
those along with a simple example of how to do this."
This commit is contained in:
Robert Osfield
2007-12-11 15:55:02 +00:00
parent 669e86145c
commit be5f709bdb
6 changed files with 451 additions and 85 deletions
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246
examples/osgsharedarray/osgsharedarray.cpp Normal file
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/* OpenSceneGraph example, osgsharedarray.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include <osg/Array>
#include <osg/Geode>
#include <osg/Geometry>
#include <osgViewer/Viewer>
/** This class is an example of how to create your own subclass of osg::Array. This
* is useful if your application has data in its own form of storage and you don't
* want to make another copy into one of the predefined osg::Array classes.
*
* @note This is not really intended to be a useful subclass of osg::Array. It
* doesn't do anything smart about memory management. It is simply intended as
* an example you can follow to create your own subclasses of osg::Array for
* your application's storage requirements.
*/
class MyArray : public osg::Array {
public:
/** Default ctor. Creates an empty array. */
MyArray() :
osg::Array(osg::Array::Vec3ArrayType,3,GL_FLOAT),
_numElements(0),
_ptr(NULL) {
}
/** "Normal" ctor.
*
* @param no The number of elements in the array.
* @param ptr Pointer to the data. This class just keeps that
* pointer. It doesn't manage the memory.
*/
MyArray(unsigned int no, osg::Vec3* ptr) :
osg::Array(osg::Array::Vec3ArrayType,3,GL_FLOAT),
_numElements(no),
_ptr(ptr) {
}
/** Copy ctor. */
MyArray(const MyArray& other, const osg::CopyOp& copyop) :
osg::Array(osg::Array::Vec3ArrayType,3,GL_FLOAT),
_numElements(other._numElements),
_ptr(other._ptr) {
}
/** What type of object would clone return? */
virtual Object* cloneType() const {
return new MyArray();
}
/** Create a copy of the object. */
virtual osg::Object* clone(const osg::CopyOp& copyop) const {
return new MyArray(*this,copyop);
}
/** Accept method for ArrayVisitors.
*
* @note This will end up in ArrayVisitor::apply(osg::Array&).
*/
virtual void accept(osg::ArrayVisitor& av) {
av.apply(*this);
}
/** Const accept method for ArrayVisitors.
*
* @note This will end up in ConstArrayVisitor::apply(const osg::Array&).
*/
virtual void accept(osg::ConstArrayVisitor& cav) const {
cav.apply(*this);
}
/** Accept method for ValueVisitors. */
virtual void accept(unsigned int index, osg::ValueVisitor& vv) {
vv.apply(_ptr[index]);
}
/** Const accept method for ValueVisitors. */
virtual void accept(unsigned int index, osg::ConstValueVisitor& cvv) const {
cvv.apply(_ptr[index]);
}
/** Compare method.
* Return -1 if lhs element is less than rhs element, 0 if equal,
* 1 if lhs element is greater than rhs element.
*/
virtual int compare(unsigned int lhs,unsigned int rhs) const {
const osg::Vec3& elem_lhs = _ptr[lhs];
const osg::Vec3& elem_rhs = _ptr[rhs];
if (elem_lhs<elem_rhs) return -1;
if (elem_rhs<elem_lhs) return 1;
return 0;
}
/** Returns a pointer to the first element of the array. */
virtual const GLvoid* getDataPointer() const {
return _ptr;
}
/** Returns the number of elements in the array. */
virtual unsigned int getNumElements() const {
return _numElements;
}
/** Returns the number of bytes of storage required to hold
* all of the elements of the array.
*/
virtual unsigned int getTotalDataSize() const {
return _numElements * sizeof(osg::Vec3);
}
private:
unsigned int _numElements;
osg::Vec3* _ptr;
};
/** The data values for the example. Simply defines a cube with
* per-face colors and normals.
*/
namespace {
static const osg::Vec3 myVertices[] = { osg::Vec3(-1.,-1.,-1.),
osg::Vec3( 1.,-1.,-1.),
osg::Vec3(-1., 1.,-1.),
osg::Vec3( 1., 1.,-1.),
osg::Vec3(-1.,-1., 1.),
osg::Vec3( 1.,-1., 1.),
osg::Vec3(-1., 1., 1.),
osg::Vec3( 1., 1., 1.)
};
static const osg::Vec3 myNormals[] = { osg::Vec3( 0., 0., 1.),
osg::Vec3( 1., 0., 0.),
osg::Vec3( 0., 0.,-1.),
osg::Vec3(-1., 0., 0.),
osg::Vec3( 0., 1., 0.),
osg::Vec3( 0.,-1., 0.)
};
static const osg::Vec4 myColors[] = { osg::Vec4( 1., 0., 0., 1.),
osg::Vec4( 0., 1., 0., 1.),
osg::Vec4( 1., 1., 0., 1.),
osg::Vec4( 0., 0., 1., 1.),
osg::Vec4( 1., 0., 1., 1.),
osg::Vec4( 0., 1., 1., 1.)
};
static const unsigned short myIndices[] = { 4, 5, 7, 6,
5, 1, 3, 7,
1, 0, 2, 3,
0, 4, 6, 2,
6, 7, 3, 2,
0, 1, 5, 4
};
}
/** Create a Geode that describes a cube using our own
* subclass of osg::Array for the vertices. It uses
* the "regular" array classes for all of the other
* arrays.
*
* Creating your own Array class isn't really very
* useful for a tiny amount of data like this. You
* could just go ahead and copy the data into one of
* the "regular" Array classes like this does for
* normals and colors. The point of creating your
* own subclass of Array is for use with datasets
* that are much larger than anything you could
* create a simple example from. In that case, you
* might not want to create a copy of the data in
* one of the Array classes that comes with OSG, but
* instead reuse the copy your application already
* has and wrap it up in a subclass of osg::Array
* that presents the right interface for use with
* OpenSceneGraph.
*
* Note that I'm only using the shared array for the
* vertices. You could do something similar for any
* of the Geometry node's data arrays.
*/
osg::Geode* createGeometry()
{
osg::Geode* geode = new osg::Geode();
// create Geometry
osg::ref_ptr<osg::Geometry> geom(new osg::Geometry());
// add vertices using MyArray class
unsigned int numVertices = sizeof(myVertices)/sizeof(myVertices[0]);
geom->setVertexArray(new MyArray(numVertices,const_cast<osg::Vec3*>(&myVertices[0])));
// add normals
unsigned int numNormals = sizeof(myNormals)/sizeof(myNormals[0]);
geom->setNormalArray(new osg::Vec3Array(numNormals,const_cast<osg::Vec3*>(&myNormals[0])));
geom->setNormalBinding(osg::Geometry::BIND_PER_PRIMITIVE);
// add colors
unsigned int numColors = sizeof(myColors)/sizeof(myColors[0]);
osg::Vec4Array* normal_array = new osg::Vec4Array(numColors,const_cast<osg::Vec4*>(&myColors[0]));
geom->setColorArray(normal_array);
geom->setColorBinding(osg::Geometry::BIND_PER_PRIMITIVE);
// add PrimitiveSet
unsigned int numIndices = sizeof(myIndices)/sizeof(myIndices[0]);
geom->addPrimitiveSet(new osg::DrawElementsUShort(osg::PrimitiveSet::QUADS,
numIndices,
const_cast<unsigned short *>(myIndices)));
// Changing these flags will tickle different cases in
// Geometry::drawImplementation. They should all work fine
// with the shared array. Setting VertexIndices will hit
// some other cases.
geom->setUseVertexBufferObjects(false);
geom->setUseDisplayList(false);
geom->setFastPathHint(false);
geode->addDrawable( geom.get() );
return geode;
}
int main(int , char **)
{
// construct the viewer.
osgViewer::Viewer viewer;
// add model to viewer.
viewer.setSceneData( createGeometry() );
// create the windows and run the threads.
return viewer.run();
}