IndexedTessellator.h

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#ifndef IndexedTessellator_INCLUDE_ONCE
#define IndexedTessellator_INCLUDE_ONCE

#include <vlGraphics/OpenGL.hpp>
#include <vlGraphics/Geometry.hpp>
#include <vlCore/Vector3.hpp>
#include <vector>

#ifndef CALLBACK
#define CALLBACK
#endif

namespace vl
{
    /**
     * Tessellates a complex polygon defined by a set of outlines into a set of triangles that can be rendered by Visualization Library.
     * For more information see the OpenGL Programmer's Guide chapter #11 "Tessellators and Quadrics".
     */
    class VLGRAPHICS_EXPORT IndexedTessellator: public Object
    {
    VL_INSTRUMENT_CLASS(vl::Tessellator, Object)

        typedef void (CALLBACK *callback_type)(void);
    public:

        //! Constructor.
        IndexedTessellator();

        //! Destructor
        ~IndexedTessellator();

        //! The contours that specify the complex polygon to be tessellated.
        const std::vector<dvec3>& contourVerts() const { return mContourVerts; }

        //! The contours that specify the complex polygon to be tessellated.
        std::vector<dvec3>& contourVerts() { return mContourVerts; }

        //! The indices of the contour vertices.
        const std::vector<int>& indices() const { return mIndices; }

        //! The indices of the contour vertices.
        std::vector<int>& indices() { return mIndices; }

        //! The contours that specify the complex polygon to be tessellated.
        const std::vector<int>& contours() const { return mContours; }

        //! The contours that specify the complex polygon to be tessellated.
        std::vector<int>& contours() { return mContours; }

        //! A set of triangles representing the tessellated polygon.
        const std::vector<int>& tessellatedTris() const { return mTessellatedTris; }

        //! A set of triangles representing the tessellated polygon.
        std::vector<int>& tessellatedTris() { return mTessellatedTris; }

        //! Newly generated vertices.
        const std::vector<vl::fvec3>& combinedVerts() const { return mCombinedVertices; }

        //! Newly generated vertices.
        std::vector<vl::fvec3>& combinedVerts() { return mCombinedVertices; }

        //! See gluTessNormal documentation.
        void setTessNormal(const fvec3& normal) { mTessNormal = normal; }

        //! See gluTessNormal documentation.
        const fvec3& tessNormal() const { return mTessNormal; }

        //! See gluTessProperty documentation (GLU_TESS_BOUNDARY_ONLY)
        void setBoundaryOnly(bool on) { mBoundaryOnly = on; }

        //! See gluTessProperty documentation (GLU_TESS_BOUNDARY_ONLY)
        bool boundaryOnly() const { return mBoundaryOnly; }

        //! See gluTessProperty documentation (GLU_TESS_TOLERANCE)
        double tolerance() const { return mTolerance; }

        //! See gluTessProperty documentation (GLU_TESS_TOLERANCE)
        void setTolerance(double tolerance) { mTolerance = tolerance; }

        //! See gluTessProperty documentation (GLU_TESS_WINDING_RULE)
        ETessellationWinding windingRule() const { return mWindingRule; }

        //! See gluTessProperty documentation (GLU_TESS_WINDING_RULE)
        void setWindingRule(ETessellationWinding rule) { mWindingRule = rule; }

        /*
         * Tessellates the specified polygon.
         * If \p append_tessellated_tris equals \p true then the previously tessellated triangles are kept and the newly
         * generated triangles are appended to them. This is useful when one has to tessellate several triangles and
         * the result should be accumulated in a single triangle set.
         *
         * After the function is called the contours() and contourVerts() are cleared.
         */
        bool tessellate(bool append_tessellated_tris=false);

        void setTessellateIntoSinglePolygon(bool on) { mTessellateIntoSinglePolygon = on; }

        bool tessellateIntoSinglePolygon() const { return mTessellateIntoSinglePolygon; }

    protected:
        static void CALLBACK tessBeginData( GLenum type, IndexedTessellator* tessellator );
        static void CALLBACK tessVertexData( int vec, IndexedTessellator* tessellator );
        static void CALLBACK tessCombineData( GLdouble coords[3], dvec3 *d[4], GLfloat w[4], void **dataOut, IndexedTessellator* tessellator );
        static void CALLBACK tessEnd(void);
        static void CALLBACK tessError( GLenum errno );
        void freeCombinedVertices();

    protected:
        // input
        std::vector<int> mContours;
        std::vector<dvec3> mContourVerts;
        std::vector<int> mIndices;
        // output
        std::vector<int> mTessellatedTris;
        // intermediate data
        std::vector< std::vector<int> > mFans;
        std::vector< std::vector<int> > mTriStrips;
        std::vector< std::vector<int> > mLineLoops;
        std::vector<fvec3> mCombinedVertices;
        GLenum mPrimitiveType;
        // see gluTessNorml()
        fvec3 mTessNormal;
        // see GLU_TESS_BOUNDARY_ONLY
        bool mBoundaryOnly;
        // see GLU_TESS_TOLERANCE
        double mTolerance;
        // see GLU_TESS_WINDING_RULE
        ETessellationWinding mWindingRule;
        // tessellate into a single polygon
        bool mTessellateIntoSinglePolygon;
    };

}

#endif