OpenSceneGraph/include/osg/TemplatePrimitiveFunctor

/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2006 Robert Osfield
 *
 * This library is open source and may be redistributed and/or modified under
 * the terms of the OpenSceneGraph Public License (OSGPL) version 0.0 or
 * (at your option) any later version.  The full license is in LICENSE file
 * included with this distribution, and on the openscenegraph.org website.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * OpenSceneGraph Public License for more details.
*/

#ifndef OSG_TERMPLATEPRIMITIVEFUNCTOR
#define OSG_TERMPLATEPRIMITIVEFUNCTOR 1

#include <osg/PrimitiveSet>
#include <osg/Notify>

namespace osg {


    /** Provides access to the primitives that compose an \c osg::Drawable.
     *  <p>Notice that \c TemplatePrimitiveFunctor is a class template, and that it inherits
     *  from its template parameter \c T. This template parameter must implement
     *  <tt>operator()(const osg::Vec3 v1, const osg::Vec3 v2, const osg::Vec3
     *  v3, bool treatVertexDataAsTemporary)</tt>,
     *  <tt>operator()(const osg::Vec3 v1, const osg::Vec3 v2, bool
     *  treatVertexDataAsTemporary)</tt>, <tt>operator()(const osg::Vec3 v1,
     *  const osg::Vec3 v2, const osg::Vec3 v3, bool treatVertexDataAsTemporary)</tt>,
     *  and <tt>operator()(const osg::Vec3 v1, const osg::Vec3 v2, const osg::Vec3 v3,
     *  const osg::Vec3 v4, bool treatVertexDataAsTemporary)</tt> which will be called
     *  for the matching primitive when the functor is applied to a \c Drawable.
     *  Parameters \c v1, \c v2, \c v3, and \c v4 are the vertices of the primitive.
     *  The last parameter, \c treatVertexDataAsTemporary, indicates whether these
     *  vertices are coming from a "real" vertex array, or from a temporary vertex array,
     *  created by the \c TemplatePrimitiveFunctor from some other geometry representation.
     *  @see \c PrimitiveFunctor for general usage hints.
     */
    template<class T>
    class TemplatePrimitiveFunctor : public PrimitiveFunctor, public T
    {
    public:

        TemplatePrimitiveFunctor()
        {
            _vertexArraySize=0;
            _vertexArrayPtr=0;
            _modeCache=0;
            _treatVertexDataAsTemporary=false;
        }

        virtual ~TemplatePrimitiveFunctor() {}

        void setTreatVertexDataAsTemporary(bool treatVertexDataAsTemporary) { _treatVertexDataAsTemporary=treatVertexDataAsTemporary; }
        bool getTreatVertexDataAsTemporary() const { return _treatVertexDataAsTemporary; }

        virtual void setVertexArray(unsigned int,const Vec2*)
        {
            notify(WARN)<<"Triangle Functor does not support Vec2* vertex arrays"<<std::endl;
        }

        virtual void setVertexArray(unsigned int count,const Vec3* vertices)
        {
            _vertexArraySize = count;
            _vertexArrayPtr = vertices;
        }

        virtual void setVertexArray(unsigned int,const Vec4* )
        {
            notify(WARN)<<"Triangle Functor does not support Vec4* vertex arrays"<<std::endl;
        }


        virtual void drawArrays(GLenum mode,GLint first,GLsizei count)
        {
            if (_vertexArrayPtr==0 || count==0) return;

            switch(mode)
                {
                case(GL_TRIANGLES): {
                    const Vec3* vlast = &_vertexArrayPtr[first+count];
                    for(const Vec3* vptr=&_vertexArrayPtr[first];vptr<vlast;vptr+=3)
                        this->operator()(*(vptr),*(vptr+1),*(vptr+2),_treatVertexDataAsTemporary);
                    break;
                }
                case(GL_TRIANGLE_STRIP): {
                    const Vec3* vptr = &_vertexArrayPtr[first];
                    for(GLsizei i=2;i<count;++i,++vptr)
                    {
                        if ((i%2)) this->operator()(*(vptr),*(vptr+2),*(vptr+1),_treatVertexDataAsTemporary);
                        else       this->operator()(*(vptr),*(vptr+1),*(vptr+2),_treatVertexDataAsTemporary);
                    }
                    break;
                }
                case(GL_QUADS): {
                    const Vec3* vptr = &_vertexArrayPtr[first];
                    for(GLsizei i=3;i<count;i+=4,vptr+=4)
                    {
                        this->operator()(*(vptr),*(vptr+1),*(vptr+2),*(vptr+3),_treatVertexDataAsTemporary);
                    }
                    break;
                }
                case(GL_QUAD_STRIP): {
                    const Vec3* vptr = &_vertexArrayPtr[first];
                    for(GLsizei i=3;i<count;i+=2,vptr+=2)
                    {
                        this->operator()(*(vptr),*(vptr+1),*(vptr+3),*(vptr+2),_treatVertexDataAsTemporary);
                    }
                    break;
                }
                case(GL_POLYGON): // treat polygons as GL_TRIANGLE_FAN
                case(GL_TRIANGLE_FAN): {
                    const Vec3* vfirst = &_vertexArrayPtr[first];
                    const Vec3* vptr = vfirst+1;
                    for(GLsizei i=2;i<count;++i,++vptr)
                    {
                        this->operator()(*(vfirst),*(vptr),*(vptr+1),_treatVertexDataAsTemporary);
                    }
                    break;
                }
                case(GL_POINTS): {
                    const Vec3* vlast = &_vertexArrayPtr[first+count];
                    for(const Vec3* vptr=&_vertexArrayPtr[first];vptr<vlast;vptr+=1)
                        this->operator()(*(vptr),_treatVertexDataAsTemporary);
                    break;
                }
                case(GL_LINES): {
                    const Vec3* vlast = &_vertexArrayPtr[first+count];
                    for(const Vec3* vptr=&_vertexArrayPtr[first];vptr<vlast;vptr+=2)
                        this->operator()(*(vptr),*(vptr+1),_treatVertexDataAsTemporary);
                    break;
                }
                case(GL_LINE_STRIP): {
                    const Vec3* vlast = &_vertexArrayPtr[first+count];
                    for(const Vec3* vptr=&_vertexArrayPtr[first];vptr<vlast;vptr+=1)
                        this->operator()(*(vptr),*(vptr+1),_treatVertexDataAsTemporary);
                    break;
                }
                case(GL_LINE_LOOP): {
                    const Vec3* vlast = &_vertexArrayPtr[first+count];
                    for(const Vec3* vptr=&_vertexArrayPtr[first];vptr<vlast;vptr+=1)
                        this->operator()(*(vptr),*(vptr+1),_treatVertexDataAsTemporary);
                    this->operator()(*(vlast-1),_vertexArrayPtr[first],_treatVertexDataAsTemporary);
                    break;
                }
                default:
                    break;
                }
        }

        template<class IndexType>
        void drawElementsTemplate(GLenum mode,GLsizei count,const IndexType* indices)
        {
            if (indices==0 || count==0) return;

            typedef const IndexType* IndexPointer;

            switch(mode)
                {
                case(GL_TRIANGLES): {
                    IndexPointer ilast = &indices[count];
                    for(IndexPointer  iptr=indices;iptr<ilast;iptr+=3)
                        this->operator()(_vertexArrayPtr[*iptr],_vertexArrayPtr[*(iptr+1)],_vertexArrayPtr[*(iptr+2)],_treatVertexDataAsTemporary);
                    break;
                }
                case(GL_TRIANGLE_STRIP): {
                    IndexPointer iptr = indices;
                    for(GLsizei i=2;i<count;++i,++iptr)
                    {
                        if ((i%2)) this->operator()(_vertexArrayPtr[*(iptr)],_vertexArrayPtr[*(iptr+2)],
                                                    _vertexArrayPtr[*(iptr+1)],_treatVertexDataAsTemporary);
                        else       this->operator()(_vertexArrayPtr[*(iptr)],_vertexArrayPtr[*(iptr+1)],
                                                    _vertexArrayPtr[*(iptr+2)],_treatVertexDataAsTemporary);
                    }
                    break;
                }
                case(GL_QUADS): {
                    IndexPointer iptr = indices;
                    for(GLsizei i=3;i<count;i+=4,iptr+=4)
                    {
                        this->operator()(_vertexArrayPtr[*(iptr)],_vertexArrayPtr[*(iptr+1)],
                                         _vertexArrayPtr[*(iptr+2)],_vertexArrayPtr[*(iptr+3)],
                                         _treatVertexDataAsTemporary);
                    }
                    break;
                }
                case(GL_QUAD_STRIP): {
                    IndexPointer iptr = indices;
                    for(GLsizei i=3;i<count;i+=2,iptr+=2)
                    {
                        this->operator()(_vertexArrayPtr[*(iptr)],_vertexArrayPtr[*(iptr+1)],
                                         _vertexArrayPtr[*(iptr+3)],_vertexArrayPtr[*(iptr+2)],
                                         _treatVertexDataAsTemporary);
                    }
                    break;
                }
                case(GL_POLYGON): // treat polygons as GL_TRIANGLE_FAN
                case(GL_TRIANGLE_FAN): {
                    IndexPointer iptr = indices;
                    const Vec3& vfirst = _vertexArrayPtr[*iptr];
                    ++iptr;
                    for(GLsizei i=2;i<count;++i,++iptr)
                    {
                        this->operator()(vfirst,_vertexArrayPtr[*(iptr)],_vertexArrayPtr[*(iptr+1)],
                                         _treatVertexDataAsTemporary);
                    }
                    break;
                }
                case(GL_POINTS): {
                    IndexPointer ilast = &indices[count];
                    for(IndexPointer  iptr=indices;iptr<ilast;iptr+=1)
                        this->operator()(_vertexArrayPtr[*iptr],_treatVertexDataAsTemporary);
                    break;
                }
                case(GL_LINES): {
                    IndexPointer ilast = &indices[count];
                    for(IndexPointer  iptr=indices;iptr<ilast;iptr+=2)
                        this->operator()(_vertexArrayPtr[*iptr],_vertexArrayPtr[*(iptr+1)],
                                         _treatVertexDataAsTemporary);
                    break;
                }
                case(GL_LINE_STRIP): {
                    IndexPointer ilast = &indices[count];
                    for(IndexPointer  iptr=indices;iptr<ilast;iptr+=1)
                        this->operator()(_vertexArrayPtr[*iptr],_vertexArrayPtr[*(iptr+1)],
                                         _treatVertexDataAsTemporary);
                    break;
                }
                case(GL_LINE_LOOP): {
                    IndexPointer ilast = &indices[count];
                    for(IndexPointer  iptr=indices;iptr<ilast;iptr+=1)
                        this->operator()(_vertexArrayPtr[*iptr],_vertexArrayPtr[*(iptr+1)],
                                         _treatVertexDataAsTemporary);
                    break;
                    this->operator()(_vertexArrayPtr[*(ilast-1)],_vertexArrayPtr[indices[0]],
                                     _treatVertexDataAsTemporary);
                }
                default:
                    break;
                }
        }


        virtual void drawElements(GLenum mode,GLsizei count,const GLubyte* indices)
        {
            drawElementsTemplate(mode, count, indices);
        }

        virtual void drawElements(GLenum mode,GLsizei count,const GLushort* indices)
        {
            drawElementsTemplate(mode, count, indices);
        }

        virtual void drawElements(GLenum mode,GLsizei count,const GLuint* indices)
        {
            drawElementsTemplate(mode, count, indices);
        }

        /** Note:
         * begin(..),vertex(..) & end() are convenience methods for adapting
         * non vertex array primitives to vertex array based primitives.
         * This is done to simplify the implementation of primtive functor
         * subclasses - users only need override drawArray and drawElements.
         */
        virtual void begin(GLenum mode)
        {
            _modeCache = mode;
            _vertexCache.clear();
        }

        virtual void vertex(const Vec2& vert) { _vertexCache.push_back(osg::Vec3(vert[0],vert[1],0.0f)); }
        virtual void vertex(const Vec3& vert) { _vertexCache.push_back(vert); }
        virtual void vertex(const Vec4& vert) { _vertexCache.push_back(osg::Vec3(vert[0],vert[1],vert[2])/vert[3]); }
        virtual void vertex(float x,float y) { _vertexCache.push_back(osg::Vec3(x,y,0.0f)); }
        virtual void vertex(float x,float y,float z) { _vertexCache.push_back(osg::Vec3(x,y,z)); }
        virtual void vertex(float x,float y,float z,float w) { _vertexCache.push_back(osg::Vec3(x,y,z)/w); }
        virtual void end()
        {
            if (!_vertexCache.empty())
            {
                setVertexArray(_vertexCache.size(),&_vertexCache.front());
                _treatVertexDataAsTemporary = true;
                drawArrays(_modeCache,0,_vertexCache.size());
            }
        }

    protected:


        unsigned int        _vertexArraySize;
        const Vec3*         _vertexArrayPtr;

        GLenum              _modeCache;
        std::vector<Vec3>   _vertexCache;
        bool                _treatVertexDataAsTemporary;
    };


}

#endif