tried to add assimp (spoilers, it did not go well, so hey! now we have separate fiels now.)

src/ThirdParty/assimp/code/AssetLib/Blender/BlenderCustomData.cpp

@@ -0,0 +1,183 @@
+#include "BlenderCustomData.h"
+#include "BlenderDNA.h"
+#include <array>
+#include <functional>
+
+namespace Assimp {
+namespace Blender {
+/**
+        *   @brief  read/convert of Structure array to memory
+        */
+template <typename T>
+bool read(const Structure &s, T *p, const size_t cnt, const FileDatabase &db) {
+    for (size_t i = 0; i < cnt; ++i) {
+        T read;
+        s.Convert(read, db);
+        *p = read;
+        p++;
+    }
+    return true;
+}
+
+/**
+        *   @brief  pointer to function read memory for n CustomData types
+        */
+typedef bool (*PRead)(ElemBase *pOut, const size_t cnt, const FileDatabase &db);
+typedef ElemBase *(*PCreate)(const size_t cnt);
+typedef void (*PDestroy)(ElemBase *);
+
+#define IMPL_STRUCT_READ(ty)                                               \
+    bool read##ty(ElemBase *v, const size_t cnt, const FileDatabase &db) { \
+        ty *ptr = dynamic_cast<ty *>(v);                                   \
+        if (nullptr == ptr) {                                              \
+            return false;                                                  \
+        }                                                                  \
+        return read<ty>(db.dna[#ty], ptr, cnt, db);                        \
+    }
+
+#define IMPL_STRUCT_CREATE(ty)               \
+    ElemBase *create##ty(const size_t cnt) { \
+        return new ty[cnt];                  \
+    }
+
+#define IMPL_STRUCT_DESTROY(ty)         \
+    void destroy##ty(ElemBase *pE) {    \
+        ty *p = dynamic_cast<ty *>(pE); \
+        delete[] p;                     \
+    }
+
+/**
+        *   @brief  helper macro to define Structure functions
+        */
+#define IMPL_STRUCT(ty)    \
+    IMPL_STRUCT_READ(ty)   \
+    IMPL_STRUCT_CREATE(ty) \
+    IMPL_STRUCT_DESTROY(ty)
+
+// supported structures for CustomData
+IMPL_STRUCT(MVert)
+IMPL_STRUCT(MEdge)
+IMPL_STRUCT(MFace)
+IMPL_STRUCT(MTFace)
+IMPL_STRUCT(MTexPoly)
+IMPL_STRUCT(MLoopUV)
+IMPL_STRUCT(MLoopCol)
+IMPL_STRUCT(MPoly)
+IMPL_STRUCT(MLoop)
+
+/**
+        *   @brief  describes the size of data and the read function to be used for single CustomerData.type
+        */
+struct CustomDataTypeDescription {
+    PRead Read; ///< function to read one CustomData type element
+    PCreate Create; ///< function to allocate n type elements
+    PDestroy Destroy;
+
+    CustomDataTypeDescription(PRead read, PCreate create, PDestroy destroy) :
+            Read(read), Create(create), Destroy(destroy) {}
+};
+
+/**
+        *   @brief  helper macro to define Structure type specific CustomDataTypeDescription
+        *   @note   IMPL_STRUCT_READ for same ty must be used earlier to implement the typespecific read function
+        */
+#define DECL_STRUCT_CUSTOMDATATYPEDESCRIPTION(ty) \
+    CustomDataTypeDescription { &read##ty, &create##ty, &destroy##ty }
+
+/**
+        *   @brief  helper macro to define CustomDataTypeDescription for UNSUPPORTED type
+        */
+#define DECL_UNSUPPORTED_CUSTOMDATATYPEDESCRIPTION \
+    CustomDataTypeDescription { nullptr, nullptr, nullptr }
+
+/**
+        *   @brief  descriptors for data pointed to from CustomDataLayer.data
+        *   @note   some of the CustomData uses already well defined Structures
+        *           other (like CD_ORCO, ...) uses arrays of rawtypes or even arrays of Structures
+        *           use a special readfunction for that cases
+        */
+static const std::array<CustomDataTypeDescription, CD_NUMTYPES> customDataTypeDescriptions = { {
+        DECL_STRUCT_CUSTOMDATATYPEDESCRIPTION(MVert),
+        DECL_UNSUPPORTED_CUSTOMDATATYPEDESCRIPTION,
+        DECL_UNSUPPORTED_CUSTOMDATATYPEDESCRIPTION,
+        DECL_STRUCT_CUSTOMDATATYPEDESCRIPTION(MEdge),
+        DECL_STRUCT_CUSTOMDATATYPEDESCRIPTION(MFace),
+        DECL_STRUCT_CUSTOMDATATYPEDESCRIPTION(MTFace),
+        DECL_UNSUPPORTED_CUSTOMDATATYPEDESCRIPTION,
+        DECL_UNSUPPORTED_CUSTOMDATATYPEDESCRIPTION,
+        DECL_UNSUPPORTED_CUSTOMDATATYPEDESCRIPTION,
+        DECL_UNSUPPORTED_CUSTOMDATATYPEDESCRIPTION,
+
+        DECL_UNSUPPORTED_CUSTOMDATATYPEDESCRIPTION,
+        DECL_UNSUPPORTED_CUSTOMDATATYPEDESCRIPTION,
+        DECL_UNSUPPORTED_CUSTOMDATATYPEDESCRIPTION,
+        DECL_UNSUPPORTED_CUSTOMDATATYPEDESCRIPTION,
+        DECL_UNSUPPORTED_CUSTOMDATATYPEDESCRIPTION,
+        DECL_STRUCT_CUSTOMDATATYPEDESCRIPTION(MTexPoly),
+        DECL_STRUCT_CUSTOMDATATYPEDESCRIPTION(MLoopUV),
+        DECL_STRUCT_CUSTOMDATATYPEDESCRIPTION(MLoopCol),
+        DECL_UNSUPPORTED_CUSTOMDATATYPEDESCRIPTION,
+        DECL_UNSUPPORTED_CUSTOMDATATYPEDESCRIPTION,
+
+        DECL_UNSUPPORTED_CUSTOMDATATYPEDESCRIPTION,
+        DECL_UNSUPPORTED_CUSTOMDATATYPEDESCRIPTION,
+        DECL_UNSUPPORTED_CUSTOMDATATYPEDESCRIPTION,
+        DECL_UNSUPPORTED_CUSTOMDATATYPEDESCRIPTION,
+        DECL_UNSUPPORTED_CUSTOMDATATYPEDESCRIPTION,
+        DECL_STRUCT_CUSTOMDATATYPEDESCRIPTION(MPoly),
+        DECL_STRUCT_CUSTOMDATATYPEDESCRIPTION(MLoop),
+        DECL_UNSUPPORTED_CUSTOMDATATYPEDESCRIPTION,
+        DECL_UNSUPPORTED_CUSTOMDATATYPEDESCRIPTION,
+        DECL_UNSUPPORTED_CUSTOMDATATYPEDESCRIPTION,
+
+        DECL_UNSUPPORTED_CUSTOMDATATYPEDESCRIPTION,
+        DECL_UNSUPPORTED_CUSTOMDATATYPEDESCRIPTION,
+        DECL_UNSUPPORTED_CUSTOMDATATYPEDESCRIPTION,
+        DECL_UNSUPPORTED_CUSTOMDATATYPEDESCRIPTION,
+        DECL_UNSUPPORTED_CUSTOMDATATYPEDESCRIPTION,
+        DECL_UNSUPPORTED_CUSTOMDATATYPEDESCRIPTION,
+        DECL_UNSUPPORTED_CUSTOMDATATYPEDESCRIPTION,
+        DECL_UNSUPPORTED_CUSTOMDATATYPEDESCRIPTION,
+        DECL_UNSUPPORTED_CUSTOMDATATYPEDESCRIPTION,
+        DECL_UNSUPPORTED_CUSTOMDATATYPEDESCRIPTION,
+
+        DECL_UNSUPPORTED_CUSTOMDATATYPEDESCRIPTION,
+        DECL_UNSUPPORTED_CUSTOMDATATYPEDESCRIPTION 
+} };
+
+bool isValidCustomDataType(const int cdtype) {
+    return cdtype >= 0 && cdtype < CD_NUMTYPES;
+}
+
+bool readCustomData(std::shared_ptr<ElemBase> &out, const int cdtype, const size_t cnt, const FileDatabase &db) {
+    if (!isValidCustomDataType(cdtype)) {
+        throw Error("CustomData.type ", cdtype, " out of index");
+    }
+
+    const CustomDataTypeDescription cdtd = customDataTypeDescriptions[cdtype];
+    if (cdtd.Read && cdtd.Create && cdtd.Destroy && cnt > 0) {
+        // allocate cnt elements and parse them from file
+        out.reset(cdtd.Create(cnt), cdtd.Destroy);
+        return cdtd.Read(out.get(), cnt, db);
+    }
+    return false;
+}
+
+std::shared_ptr<CustomDataLayer> getCustomDataLayer(const CustomData &customdata, const CustomDataType cdtype, const std::string &name) {
+    for (auto it = customdata.layers.begin(); it != customdata.layers.end(); ++it) {
+        if (it->get()->type == cdtype && name == it->get()->name) {
+            return *it;
+        }
+    }
+    return nullptr;
+}
+
+const ElemBase *getCustomDataLayerData(const CustomData &customdata, const CustomDataType cdtype, const std::string &name) {
+    const std::shared_ptr<CustomDataLayer> pLayer = getCustomDataLayer(customdata, cdtype, name);
+    if (pLayer && pLayer->data) {
+        return pLayer->data.get();
+    }
+    return nullptr;
+}
+} // namespace Blender
+} // namespace Assimp