opensubdiv-petite-sys 0.3.1

Low-level wrapper around parts of Pixar’s OpenSubdiv
Documentation 
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#include <opensubdiv/far/patchTable.h>
#include <opensubdiv/far/stencilTable.h>
#include <opensubdiv/far/stencilTableFactory.h>
#include <vector>

#include "../vtr/types.hpp"

typedef OpenSubdiv::Far::LimitStencilTable LimitStencilTable;
typedef OpenSubdiv::Far::LimitStencilTableFactory LimitStencilTableFactory;
typedef OpenSubdiv::Far::StencilTable StencilTable;
typedef OpenSubdiv::Far::TopologyRefiner TopologyRefiner;
typedef OpenSubdiv::Far::PatchTable PatchTable;

/// Flat FFI-safe replacement for C++ LocationArray.
struct LocationArrayDesc
{
    int ptex_idx;
    int num_locations;
    const float *s;
    const float *t;
};

extern "C"
{

    void LimitStencilTable_destroy(const LimitStencilTable *table)
    {
        delete table;
    }

    /// Returns the 'u' derivative stencil interpolation weights.
    FloatVectorRef LimitStencilTable_GetDuWeights(const LimitStencilTable *table)
    {
        auto &v = table->GetDuWeights();
        return FloatVectorRef(v.data(), v.size());
    }

    /// Returns the 'v' derivative stencil interpolation weights.
    FloatVectorRef LimitStencilTable_GetDvWeights(const LimitStencilTable *table)
    {
        auto &v = table->GetDvWeights();
        return FloatVectorRef(v.data(), v.size());
    }

    /// Returns the 'uu' derivative stencil interpolation weights.
    FloatVectorRef LimitStencilTable_GetDuuWeights(const LimitStencilTable *table)
    {
        auto &v = table->GetDuuWeights();
        return FloatVectorRef(v.data(), v.size());
    }

    /// Returns the 'uv' derivative stencil interpolation weights.
    FloatVectorRef LimitStencilTable_GetDuvWeights(const LimitStencilTable *table)
    {
        auto &v = table->GetDuvWeights();
        return FloatVectorRef(v.data(), v.size());
    }

    /// Returns the 'vv' derivative stencil interpolation weights.
    FloatVectorRef LimitStencilTable_GetDvvWeights(const LimitStencilTable *table)
    {
        auto &v = table->GetDvvWeights();
        return FloatVectorRef(v.data(), v.size());
    }

    /// Create a LimitStencilTable via the factory.
    ///
    /// `options_bitfield` layout: [1:0] interpolationMode, [2] generate1stDerivatives,
    /// [3] generate2ndDerivatives.
    /// `fvar_channel` is passed separately.
    ///
    /// `cv_stencils` and `patch_table` may be null.
    const LimitStencilTable *LimitStencilTableFactory_Create(
        const TopologyRefiner *refiner,
        const LocationArrayDesc *location_descs,
        int num_arrays,
        const StencilTable *cv_stencils,
        const PatchTable *patch_table,
        unsigned int options_bitfield,
        unsigned int fvar_channel)
    {
        // Rebuild the C++ LocationArrayVec from the flat descriptors.
        LimitStencilTableFactory::LocationArrayVec locations(num_arrays);
        for (int i = 0; i < num_arrays; ++i) {
            locations[i].ptexIdx = location_descs[i].ptex_idx;
            locations[i].numLocations = location_descs[i].num_locations;
            locations[i].s = location_descs[i].s;
            locations[i].t = location_descs[i].t;
        }

        // Unpack bitfield into Options.
        LimitStencilTableFactory::Options options;
        options.interpolationMode = options_bitfield & 0x3;
        options.generate1stDerivatives = (options_bitfield >> 2) & 0x1;
        options.generate2ndDerivatives = (options_bitfield >> 3) & 0x1;
        options.fvarChannel = fvar_channel;

        return LimitStencilTableFactory::Create(
            *refiner, locations, cv_stencils, patch_table, options);
    }

}  // extern "C"