TriangleLinePointIndexFunctor.h

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/* -*-c++-*- OpenSceneGraph - Copyright (C) Sketchfab
 *
 * This application is open source and may be redistributed and/or modified
 * freely and without restriction, both in commercial and non commercial
 * applications, as long as this copyright notice is maintained.
 *
 * This application 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.
 *
 */

#ifndef TRIANGLE_LINE_POINT_INDEX_FUNCTOR
#define TRIANGLE_LINE_POINT_INDEX_FUNCTOR

#include <osg/PrimitiveSet>
#include <osg/Array>


template<class T>
class TriangleLinePointIndexFunctor : public osg::PrimitiveIndexFunctor, public T
{
public:
    virtual void setVertexArray(unsigned int,const osg::Vec2*)
    {}

    virtual void setVertexArray(unsigned int ,const osg::Vec3* )
    {}

    virtual void setVertexArray(unsigned int,const osg::Vec4* )
    {}

    virtual void setVertexArray(unsigned int,const osg::Vec2d*)
    {}

    virtual void setVertexArray(unsigned int ,const osg::Vec3d* )
    {}

    virtual void setVertexArray(unsigned int,const osg::Vec4d* )
    {}

    virtual void begin(GLenum mode) {
        _modeCache = mode;
        _indexCache.clear();
    }

    virtual void vertex(unsigned int vert) {
        _indexCache.push_back(vert);
    }

    virtual void end() {
        if (!_indexCache.empty()) {
            drawElements(_modeCache,_indexCache.size(),&_indexCache.front());
        }
    }

    virtual void drawArrays(GLenum mode, GLint first, GLsizei count) {
        switch(mode)
        {
            case(GL_TRIANGLES):
            {
                unsigned int pos=first;
                for(GLsizei i = 2 ; i < count ; i += 3, pos += 3) {
                    this->operator()(pos, pos + 1, pos + 2);
                }
                break;
            }
            case(GL_TRIANGLE_STRIP):
             {
                unsigned int pos = first;
                for(GLsizei i = 2 ; i < count ; ++ i, ++ pos) {
                    if ((i%2)) this->operator()(pos, pos + 2, pos + 1);
                    else       this->operator()(pos, pos + 1, pos + 2);
                }
                break;
            }
            case(GL_QUADS):
            {
                unsigned int pos = first;
                for(GLsizei i = 3 ; i < count ; i += 4, pos += 4) {
                    this->operator()(pos,pos + 1, pos + 2);
                    this->operator()(pos,pos + 2, pos + 3);
                }
                break;
            }
            case(GL_QUAD_STRIP):
            {
                unsigned int pos = first;
                for(GLsizei i = 3 ; i < count ; i += 2, pos += 2) {
                    this->operator()(pos, pos + 1,pos + 2);
                    this->operator()(pos + 1,pos + 3,pos + 2);
                }
                break;
            }
            case(GL_POLYGON): // treat polygons as GL_TRIANGLE_FAN
            case(GL_TRIANGLE_FAN):
            {
                unsigned int pos = first + 1;
                for(GLsizei i = 2 ; i < count ; ++ i, ++ pos) {
                    this->operator()(first, pos, pos + 1);
                }
                break;
            }
            case(GL_LINES):
            {
                unsigned int pos = first;
                for(GLsizei i = 0 ; i < count ; i += 2, pos += 2) {
                    this->operator()(pos, pos + 1);
                }
                break;
            }
            case(GL_LINE_STRIP):
            {
                unsigned int pos = first;
                for(GLsizei i = 0 ; i < count - 1 ; i += 1, pos += 1) {
                    this->operator()(pos, pos + 1);
                }
                break;
            }
            case(GL_LINE_LOOP):
            {
                unsigned int pos = first;
                for(GLsizei i = 0 ; i < count - 1 ; i += 1, pos += 1) {
                    this->operator()(pos, pos + 1);
                }
                this->operator()(pos, first);
                break;
            }
            case(GL_POINTS):
            {
                unsigned int pos=first;
                for(GLsizei i = 0 ; i < count ; ++ i) {
                    this->operator()(pos + i);
                }
                break;
            }
            default:
                break;
        }
    }

    template<typename I>
    void drawElements(GLenum mode, GLsizei count, const I* indices)
    {
        typedef I Index;
        typedef const I* IndexPointer;

        if (indices == 0 || count == 0) {
            return;
        }

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

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

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

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


    GLenum                    _modeCache;
    std::vector<GLuint>       _indexCache;
    std::vector<unsigned int> _remap;
};

#endif