/* -*-c++-*- */
/* osgEarth - Geospatial SDK for OpenSceneGraph
* Copyright 2020 Pelican Mapping
* http://osgearth.org
*
* osgEarth is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* 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.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program.  If not, see <http://www.gnu.org/licenses/>
*/
#ifndef OSGEARTH_TESSELLATOR_H
#define OSGEARTH_TESSELLATOR_H 1

#include <osgEarth/Common>
#include <osgEarth/Geometry>
#include <osg/Geometry>
    
namespace osgEarth { namespace Util
{
    /**
     * Polygon tessellator using a modified ear clipping technique
     */
    class OSGEARTH_EXPORT Tessellator
    {
    public:
        enum Plane {
            PLANE_XY,
            PLANE_AUTO
        };

        //! Take a geometry and output a triangulated mesh in the form of
        //! an index vector. By default it will tessellate in the XY plane
        //! and ignore the Z value. You can pass in AUTO and it will
        //! attempt to pick the "dominant" plane of the geometry and tessellate
        //! in that plane.
        bool tessellate2D(
            const osgEarth::Geometry* geom,
            std::vector<uint32_t>& out_indices,
            Plane plane = PLANE_XY) const;

        //! Old method to tessellate a pre-existing geometry object
        bool tessellateGeometry(
            osg::Geometry &geom);

    protected:
        osg::PrimitiveSet* tessellatePrimitive(osg::PrimitiveSet* primitive, osg::Vec3Array* vertices);
        osg::PrimitiveSet* tessellatePrimitive(unsigned int first, unsigned int last, osg::Vec3Array* vertices);

        bool isConvex(const osg::Vec3Array &vertices, const std::vector<unsigned int> &activeVerts, unsigned int cursor);
        bool isEar(const osg::Vec3Array &vertices, const std::vector<unsigned int> &activeVerts, unsigned int cursor, bool &tradEar);
    };
} }

#endif // OSGEARTH_TESSELLATOR_H