OpenSubdiv/opensubdiv/far/patchDescriptor.h

//
//   Copyright 2013 Pixar
//
//   Licensed under the Apache License, Version 2.0 (the "Apache License")
//   with the following modification; you may not use this file except in
//   compliance with the Apache License and the following modification to it:
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//
//   6. Trademarks. This License does not grant permission to use the trade
//      names, trademarks, service marks, or product names of the Licensor
//      and its affiliates, except as required to comply with Section 4(c) of
//      the License and to reproduce the content of the NOTICE file.
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//   You may obtain a copy of the Apache License at
//
//       http://www.apache.org/licenses/LICENSE-2.0
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//   Unless required by applicable law or agreed to in writing, software
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#ifndef FAR_PATCH_DESCRIPTOR_H
#define FAR_PATCH_DESCRIPTOR_H

#include "../version.h"

#include "../sdc/type.h"

#include <vector>

namespace OpenSubdiv {
namespace OPENSUBDIV_VERSION {

namespace Far {

/// \brief Describes the type of a patch
///
/// Uniquely identifies all the different types of patches
///
/// * Uniformly subdivided meshes contain bilinear patches of either QUADS
///   or TRIANGLES
///
/// * Adaptively subdivided meshes contain bicubic patches of types REGULAR,
///   BOUNDARY, SINGLE_CREASE, CORNER, GREGORY, GREGORY_BOUNDARY, GREGOYR_BASIS.
///   These bicubic patches are also further distinguished by a transition
///   pattern as well as a rotational orientation.
///
/// Bitfield layout :
///
///  Field      | Bits | Content
///  -----------|:----:|------------------------------------------------------
///  _type      | 4    | patch type
///  _pattern   | 3    | patch transition pattern
///  _rotation  | 2    | patch rotation
///
class PatchDescriptor {

public:

    enum Type {
        NON_PATCH = 0,     ///< undefined

        POINTS,            ///< points (useful for cage drawing)
        LINES,             ///< lines  (useful for cage drawing)

        QUADS,             ///< bilinear quads-only patches
        TRIANGLES,         ///< bilinear triangles-only mesh

        LOOP,              ///< Loop patch

        REGULAR,           ///< feature-adaptive bicubic patches
        SINGLE_CREASE,
        BOUNDARY,
        CORNER,
        GREGORY,
        GREGORY_BOUNDARY,
        GREGORY_BASIS
    };

    enum TransitionPattern {
        NON_TRANSITION = 0,
        PATTERN0,
        PATTERN1,
        PATTERN2,
        PATTERN3,
        PATTERN4
    };

public:

    /// \brief Default constructor.
    PatchDescriptor() :
        _type(NON_PATCH), _pattern(NON_TRANSITION), _rotation(0) {}

    /// \brief Constructor
    PatchDescriptor(int type, int pattern, unsigned char rotation) :
        _type(type), _pattern(pattern), _rotation(rotation) { }

    /// \brief Copy Constructor
    PatchDescriptor( PatchDescriptor const & d ) :
        _type(d.GetType()), _pattern(d.GetPattern()), _rotation(d.GetRotation()) { }

    /// \brief Returns the type of the patch
    Type GetType() const {
        return (Type)_type;
    }

    /// \brief Returns the transition pattern of the patch if any (5 types)
    TransitionPattern GetPattern() const {
        return (TransitionPattern)_pattern;
    }

    /// \brief Returns the rotation of the patch (4 rotations)
    unsigned char GetRotation() const {
        return (unsigned char)_rotation;
    }

    /// \brief Returns the number of control vertices expected for a patch of the
    /// type described
    static inline short GetNumControlVertices( Type t );

    static inline short GetNumFVarControlVertices( Type t );

    /// \brief Returns the number of control vertices expected for a patch of the
    /// type described
    short GetNumControlVertices() const {
        return GetNumControlVertices( this->GetType() );
    }

    /// \brief Returns the number of control vertices expected for a patch of the
    /// type described
    short GetNumFVarControlVertices() const {
        return GetNumFVarControlVertices( this->GetType() );
    }

    /// \brief Number of control vertices of Regular Patches in table.
    static short GetRegularPatchSize() { return 16; }

    /// \brief Number of control vertices of Boundary Patches in table.
    static short GetBoundaryPatchSize() { return 12; }

    /// \brief Number of control vertices of Boundary Patches in table.
    static short GetCornerPatchSize() { return 9; }

    /// \brief Number of control vertices of Gregory (and Gregory Boundary) Patches in table.
    static short GetGregoryPatchSize() { return 4; }

    /// \brief Number of control vertices of Gregory patch basis (20)
    static short GetGregoryBasisPatchSize() { return 20; }


    /// \brief Returns a vector of all the legal patch descriptors for the
    ///        given adaptive subdivision scheme
    static std::vector<PatchDescriptor> const & GetAdaptivePatchDescriptors(Sdc::Type type);

    /// \brief Allows ordering of patches by type
    inline bool operator < ( PatchDescriptor const other ) const;

    /// \brief True if the descriptors are identical
    inline bool operator == ( PatchDescriptor const other ) const;

private:
    friend class PatchTablesFactory;

    unsigned int  _type:4;
    unsigned int  _pattern:3;
    unsigned int  _rotation:2;
};

typedef std::vector<PatchDescriptor> PatchDescriptorVector;

// Returns the number of control vertices expected for a patch of this type
inline short
PatchDescriptor::GetNumControlVertices( Type type ) {
    switch (type) {
        case REGULAR           : return GetRegularPatchSize();
        case SINGLE_CREASE     : return GetRegularPatchSize();
        case QUADS             : return 4;
        case GREGORY           :
        case GREGORY_BOUNDARY  : return GetGregoryPatchSize();
        case GREGORY_BASIS     : return GetGregoryBasisPatchSize();
        case BOUNDARY          : return GetBoundaryPatchSize();
        case CORNER            : return GetCornerPatchSize();
        case TRIANGLES         : return 3;
        case LINES             : return 2;
        case POINTS            : return 1;
        default : return -1;
    }
}

// Returns the number of face-varying control vertices expected for a patch of this type
inline short
PatchDescriptor::GetNumFVarControlVertices( Type type ) {
    switch (type) {
        case REGULAR           : // We only support bilinear interpolation for now,
        case SINGLE_CREASE     :
        case QUADS             : // so all these patches only carry 4 CVs.
        case GREGORY           :
        case GREGORY_BOUNDARY  :
        case GREGORY_BASIS     :
        case BOUNDARY          :
        case CORNER            : return 4;
        case TRIANGLES         : return 3;
        case LINES             : return 2;
        case POINTS            : return 1;
        default : return -1;
    }
}

// Allows ordering of patches by type
inline bool
PatchDescriptor::operator < ( PatchDescriptor const other ) const {
    return _pattern < other._pattern or ((_pattern == other._pattern) and
          (_type < other._type or ((_type == other._type) and
          (_rotation < other._rotation))));
}

// True if the descriptors are identical
inline bool
PatchDescriptor::operator == ( PatchDescriptor const other ) const {
    return     _pattern == other._pattern    and
                  _type == other._type       and
              _rotation == other._rotation;
}



} // end namespace Far

} // end namespace OPENSUBDIV_VERSION
using namespace OPENSUBDIV_VERSION;

} // end namespace OpenSubdiv

#endif /* FAR_PATCH_DESCRIPTOR_H */