GU_OSDTopology.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: GU_OSDTopology.h ( GU Library, C++)
 *
 * COMMENTS: Build OpenSubdiv TopologyRefiner directly from GU_Detail.
 *           Replaces GT-based topology path (GT_OSDTopology / GT_GEODetail).
 */

#pragma once

#include "GU_API.h"

#include <UT/UT_FloatArray.h>
#include <UT/UT_IntArray.h>
#include <UT/UT_Span.h>
#include <UT/UT_UniquePtr.h>

#include <opensubdiv/version.h>
namespace OpenSubdiv { namespace OPENSUBDIV_VERSION { namespace Far {
    class TopologyRefiner;
} } }

class GU_Detail;
class GU_OSDEval;

/// Builds an OpenSubdiv TopologyRefiner directly from GU_Detail polygons.
/// All polygons are treated as Catmull-Clark subdivision faces (no creases).
class GU_API GU_OSDTopology
{
public:
    GU_OSDTopology();
    ~GU_OSDTopology();

    GU_OSDTopology(const GU_OSDTopology &) = delete;
    GU_OSDTopology &operator=(const GU_OSDTopology &) = delete;
    GU_OSDTopology(GU_OSDTopology &&) noexcept;
    GU_OSDTopology &operator=(GU_OSDTopology &&) noexcept;

    /// Build topology refiner from polygon mesh in GU_Detail.
    /// Returns false if the detail has no polygons.
    bool                createFromDetail(const GU_Detail &gdp);

    bool                hasRefiner() const { return refiner() != nullptr; }

    /// Convert coarse face/u/v to patch coordinates.
    /// coarseFace values are GA primitive indices; the internal face remap
    /// is applied automatically.
    bool                convertToPatch(
                            UT_Span<const int> coarseFace,
                            UT_Span<const float> coarseU,
                            UT_Span<const float> coarseV,
                            UT_IntArray &patchFace,
                            UT_FloatArray &patchU,
                            UT_FloatArray &patchV) const;

    /// GA prim index -> topology face index.
    const UT_IntArray        &faceRemap() const { return myFaceRemap; }

    friend class GU_OSDEval;

private:
    /// Access the refiner (for GU_OSDEval::setTopology).
    const OpenSubdiv::Far::TopologyRefiner *refiner() const;

    struct State;
    UT_UniquePtr<State>     myState;
    UT_IntArray             myFaceRemap;
};