GEO_PrimTriStrip.h

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/*
 * PROPRIETARY INFORMATION.  This software is proprietary to
 * Side Effects Software Inc., and is not to be reproduced,
 * transmitted, or disclosed in any way without written permission.
 *
 * NAME:        GEO_PrimTriStrip.h ( GEO Library, C++)
 *
 * COMMENTS: Implements a normal triangle strip.
 */

#ifndef __GEO_PrimTriStrip__
#define __GEO_PrimTriStrip__

#include "GEO_API.h"
#include "GEO_TriMesh.h"
#include "GEO_PrimType.h"

class GA_Detail;

/// A strip of triangles.  The Nth triangle shares an edge with the previous.
class GEO_API GEO_PrimTriStrip : public GEO_TriMesh
{
protected:
    /// NOTE: The constructor should only be called from subclass
    ///       constructors.
    GEO_PrimTriStrip(GA_Detail *d, GA_Offset offset = GA_INVALID_OFFSET)
        : GEO_TriMesh(d, offset)
    {}

    /// NOTE: The destructor should only be called from subclass
    ///       destructors.
    ~GEO_PrimTriStrip() override {}

public:
    /// @{
    /// Interface from GEO_TriMesh
    bool            isDegenerate() const override;
    UT_Vector3      computeNormal() const override;
    UT_Vector3D     computeNormalD() const override;
    void            reverse() override;
    virtual void    reverseNormal();

    fpreal          calcVolume(const UT_Vector3 &refpt) const override;
    fpreal          calcArea() const override;
    fpreal          calcPerimeter() const override;
    /// @}

    /// Get number of triangles in the strip
    int         getTriangleCount() const        { return getVertexCount()-2; }

    /// Get the vertices for a single triangle in the strip
    void         getTriangleVertices(int idx, int &v0, int &v1, int &v2) const
                 {
                     v0 = idx;
                     if (idx & 1)
                     {
                         v1 = idx+1;
                         v2 = idx+2;
                     }
                     else
                     {
                         v1 = idx+2;
                         v2 = idx+1;
                     }
                 }

    const GA_PrimitiveJSON              *getJSON() const override;

protected:
    static GA_PrimitiveFamilyMask       buildFamilyMask()
                            { return GEO_TriMesh::buildFamilyMask(); }

    template <typename T>
    UT_Vector3T<T> internalComputeNormal() const;

    /// All subclasses should call this method to register the curve intrinsics.
    /// @see GA_IntrinsicManager
    static GA_IntrinsicManager::Registrar
                        registerIntrinsics(GA_PrimitiveDefinition &defn)
                            { return GEO_TriMesh::registerIntrinsics(defn); }

    // We don't need to save anything other than what's in a face
    bool                savePrivateH9(std::ostream &,
                                      bool binary) const override;
    bool                loadPrivateH9(UT_IStream &) override;

private:
    friend std::ostream &operator<<(std::ostream &os, const GEO_PrimTriStrip &d)
                        {
                            d.saveH9(os, 0,
                                     GEO_Primitive::theEmptySaveAttribs,
                                     GEO_Primitive::theEmptySaveAttribs);
                            return os;
                        }
};

#endif