add assimp submodule

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diff --git a/src/mesh/assimp-master/port/dAssimp/assimp/postprocess.d b/src/mesh/assimp-master/port/dAssimp/assimp/postprocess.d
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+/*
+---------------------------------------------------------------------------
+Open Asset Import Library (ASSIMP)
+---------------------------------------------------------------------------
+
+Copyright (c) 2006-2020, ASSIMP Development Team
+
+All rights reserved.
+
+Redistribution and use of this software in source and binary forms,
+with or without modification, are permitted provided that the following
+conditions are met:
+
+ * Redistributions of source code must retain the above
+  copyright notice, this list of conditions and the
+  following disclaimer.
+
+ * Redistributions in binary form must reproduce the above
+  copyright notice, this list of conditions and the
+  following disclaimer in the documentation and/or other
+  materials provided with the distribution.
+
+ * Neither the name of the ASSIMP team, nor the names of its
+  contributors may be used to endorse or promote products
+  derived from this software without specific prior
+  written permission of the ASSIMP Development Team.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+---------------------------------------------------------------------------
+*/
+
+/**
+ * Definitions for import post processing steps.
+ */
+module assimp.postprocess;
+
+extern ( C ) {
+   /**
+    * Defines the flags for all possible post processing steps.
+    *
+    * See: <code>aiImportFile</code>, <code>aiImportFileEx</code>
+    */
+   enum aiPostProcessSteps {
+      /**
+       * Calculates the tangents and bitangents for the imported meshes.
+       *
+       * Does nothing if a mesh does not have normals. You might want this post
+       * processing step to be executed if you plan to use tangent space
+       * calculations such as normal mapping applied to the meshes. There is a
+       * config setting, <code>AI_CONFIG_PP_CT_MAX_SMOOTHING_ANGLE</code>,
+       * which allows you to specify a maximum smoothing angle for the
+       * algorithm. However, usually you will want to use the default value.
+       */
+      CalcTangentSpace = 0x1,
+
+      /**
+       * Identifies and joins identical vertex data sets within all imported
+       * meshes.
+       *
+       * After this step is run each mesh does contain only unique vertices
+       * anymore, so a vertex is possibly used by multiple faces. You usually
+       * want to use this post processing step. If your application deals with
+       * indexed geometry, this step is compulsory or you will just waste
+       * rendering time. <em>If this flag is not specified</em>, no vertices
+       * are referenced by more than one face and <em>no index buffer is
+       * required</em> for rendering.
+       */
+      JoinIdenticalVertices = 0x2,
+
+      /**
+       * Converts all the imported data to a left-handed coordinate space.
+       *
+       * By default the data is returned in a right-handed coordinate space
+       * which for example OpenGL prefers. In this space, +X points to the
+       * right, +Z points towards the viewer and and +Y points upwards. In the
+       * DirectX coordinate space +X points to the right, +Y points upwards and
+       * +Z points away from the viewer.
+       *
+       * You will probably want to consider this flag if you use Direct3D for
+       * rendering. The <code>ConvertToLeftHanded</code> flag supersedes this
+       * setting and bundles all conversions typically required for D3D-based
+       * applications.
+       */
+      MakeLeftHanded = 0x4,
+
+      /**
+       * Triangulates all faces of all meshes.
+       *
+       * By default the imported mesh data might contain faces with more than 3
+       * indices. For rendering you'll usually want all faces to be triangles.
+       * This post processing step splits up all higher faces to triangles.
+       * Line and point primitives are <em>not</em> modified!.
+       *
+       * If you want »triangles only« with no other kinds of primitives,
+       * specify both <code>Triangulate</code> and <code>SortByPType</code> and
+       * ignore all point and line meshes when you process Assimp's output.
+       */
+      Triangulate = 0x8,
+
+      /**
+       * Removes some parts of the data structure (animations, materials, light
+       * sources, cameras, textures, vertex components).
+       *
+       * The components to be removed are specified in a separate configuration
+       * option, <code>AI_CONFIG_PP_RVC_FLAGS</code>. This is quite useful if
+       * you don't need all parts of the output structure. Especially vertex
+       * colors are rarely used today.
+       *
+       * Calling this step to remove unrequired stuff from the pipeline as
+       * early as possible results in an increased performance and a better
+       * optimized output data structure.
+       *
+       * This step is also useful if you want to force Assimp to recompute
+       * normals or tangents since the corresponding steps don't recompute them
+       * if they have already been loaded from the source asset.
+       *
+       * This flag is a poor one, mainly because its purpose is usually
+       * misunderstood. Consider the following case: a 3d model has been exported
+       * from a CAD app, it has per-face vertex colors. Because of the vertex
+       * colors (which are not even used by most apps),
+       * <code>JoinIdenticalVertices</code> cannot join vertices at the same
+       * position. By using this step, unneeded components are excluded as
+       * early as possible thus opening more room for internal optimzations.
+       */
+      RemoveComponent = 0x10,
+
+      /**
+       * Generates normals for all faces of all meshes.
+       *
+       * This is ignored if normals are already there at the time where this
+       * flag is evaluated. Model importers try to load them from the source
+       * file, so they are usually already there. Face normals are shared
+       * between all points of a single face, so a single point can have
+       * multiple normals, which, in other words, enforces the library to
+       * duplicate vertices in some cases. <code>JoinIdenticalVertices</code>
+       * is <em>useless</em> then.
+       *
+       * This flag may not be specified together with
+       * <code>GenSmoothNormals</code>.
+       */
+      GenNormals = 0x20,
+
+      /**
+       * Generates smooth normals for all vertices in the mesh.
+       *
+       * This is ignored if normals are already there at the time where this
+       * flag is evaluated. Model importers try to load them from the source file, so
+       * they are usually already there.
+       *
+       * There is a configuration option,
+       * <code>AI_CONFIG_PP_GSN_MAX_SMOOTHING_ANGLE</code> which allows you to
+       * specify an angle maximum for the normal smoothing algorithm. Normals
+       * exceeding this limit are not smoothed, resulting in a »hard« seam
+       * between two faces. Using a decent angle here (e.g. 80°) results in
+       * very good visual appearance.
+       */
+      GenSmoothNormals = 0x40,
+
+      /**
+       * Splits large meshes into smaller submeshes.
+       *
+       * This is quite useful for realtime rendering where the number of triangles
+       * which can be maximally processed in a single draw-call is usually limited
+       * by the video driver/hardware. The maximum vertex buffer is usually limited,
+       * too. Both requirements can be met with this step: you may specify both a
+       * triangle and vertex limit for a single mesh.
+       *
+       * The split limits can (and should!) be set through the
+       * <code>AI_CONFIG_PP_SLM_VERTEX_LIMIT</code> and
+       * <code>AI_CONFIG_PP_SLM_TRIANGLE_LIMIT</code> settings. The default
+       * values are <code>AI_SLM_DEFAULT_MAX_VERTICES</code> and
+       * <code>AI_SLM_DEFAULT_MAX_TRIANGLES</code>.
+       *
+       * Note that splitting is generally a time-consuming task, but not if
+       * there's nothing to split. The use of this step is recommended for most
+       * users.
+       */
+      SplitLargeMeshes = 0x80,
+
+      /**
+       * Removes the node graph and pre-transforms all vertices with the local
+       * transformation matrices of their nodes.
+       *
+       * The output scene does still contain nodes, however, there is only a
+       * root node with children, each one referencing only one mesh, each
+       * mesh referencing one material. For rendering, you can simply render
+       * all meshes in order, you don't need to pay attention to local
+       * transformations and the node hierarchy. Animations are removed during
+       * this step.
+       *
+       * This step is intended for applications that have no scenegraph.
+       *
+       * The step <em>can</em> cause some problems: if e.g. a mesh of the asset
+       * contains normals and another, using the same material index, does not,
+       * they will be brought together, but the first meshes's part of the
+       * normal list is zeroed. However, these artifacts are rare.
+       *
+       * Note: The <code>AI_CONFIG_PP_PTV_NORMALIZE</code> configuration
+       *    property can be set to normalize the scene's spatial dimension
+       *    to the -1...1 range.
+       */
+      PreTransformVertices = 0x100,
+
+      /**
+       * Limits the number of bones simultaneously affecting a single vertex to
+       * a maximum value.
+       *
+       * If any vertex is affected by more than that number of bones, the least
+       * important vertex weights are removed and the remaining vertex weights
+       * are renormalized so that the weights still sum up to 1.
+       *
+       * The default bone weight limit is 4 (<code>AI_LMW_MAX_WEIGHTS</code>),
+       * but you can use the <code>#AI_CONFIG_PP_LBW_MAX_WEIGHTS</code> setting
+       * to supply your own limit to the post processing step.
+       *
+       * If you intend to perform the skinning in hardware, this post processing
+       * step might be of interest for you.
+       */
+      LimitBoneWeights = 0x200,
+
+      /**
+       * Validates the imported scene data structure.
+       *
+       * This makes sure that all indices are valid, all animations and
+       * bones are linked correctly, all material references are correct, etc.
+       *
+       * It is recommended to capture Assimp's log output if you use this flag,
+       * so you can easily find ot what's actually wrong if a file fails the
+       * validation. The validator is quite rude and will find <em>all</em>
+       * inconsistencies in the data structure.
+       *
+       * Plugin developers are recommended to use it to debug their loaders.
+       *
+       * There are two types of validation failures:
+       * <ul>
+       * <li>Error: There's something wrong with the imported data. Further
+       *    postprocessing is not possible and the data is not usable at all.
+       *    The import fails, see <code>aiGetErrorString()</code> for the
+       *    error message.</li>
+       * <li>Warning: There are some minor issues (e.g. 1000000 animation
+       *   keyframes with the same time), but further postprocessing and use
+       *   of the data structure is still safe. Warning details are written
+       *   to the log file, <code>AI_SCENE_FLAGS_VALIDATION_WARNING</code> is
+       *   set in <code>aiScene::mFlags</code></li>
+       * </ul>
+       *
+       * This post-processing step is not time-consuming. It's use is not
+       * compulsory, but recommended.
+       */
+      ValidateDataStructure = 0x400,
+
+      /**
+       * Reorders triangles for better vertex cache locality.
+       *
+       * The step tries to improve the ACMR (average post-transform vertex cache
+       * miss ratio) for all meshes. The implementation runs in O(n) and is
+       * roughly based on the 'tipsify' algorithm (see
+       * <tt>http://www.cs.princeton.edu/gfx/pubs/Sander_2007_%3ETR/tipsy.pdf</tt>).
+       *
+       * If you intend to render huge models in hardware, this step might
+       * be of interest for you. The <code>AI_CONFIG_PP_ICL_PTCACHE_SIZE</code>
+       * config setting can be used to fine-tune the cache optimization.
+       */
+      ImproveCacheLocality = 0x800,
+
+      /**
+       * Searches for redundant/unreferenced materials and removes them.
+       *
+       * This is especially useful in combination with the
+       * <code>PretransformVertices</code> and <code>OptimizeMeshes</code>
+       * flags. Both join small meshes with equal characteristics, but they
+       * can't do their work if two meshes have different materials. Because
+       * several material settings are always lost during Assimp's import
+       * filters, (and because many exporters don't check for redundant
+       * materials), huge models often have materials which are are defined
+       * several times with exactly the same settings.
+       *
+       * Several material settings not contributing to the final appearance of
+       * a surface are ignored in all comparisons; the material name is one of
+       * them. So, if you are passing additional information through the
+       * content pipeline (probably using »magic« material names), don't
+       * specify this flag. Alternatively take a look at the
+       * <code>AI_CONFIG_PP_RRM_EXCLUDE_LIST</code> setting.
+       */
+      RemoveRedundantMaterials = 0x1000,
+
+      /**
+       * This step tries to determine which meshes have normal vectors that are
+       * acing inwards.
+       *
+       * The algorithm is simple but effective: The bounding box of all
+       * vertices and their normals is compared against the volume of the
+       * bounding box of all vertices without their normals. This works well
+       * for most objects, problems might occur with planar surfaces. However,
+       * the step tries to filter such cases.
+       *
+       * The step inverts all in-facing normals. Generally it is recommended to
+       * enable this step, although the result is not always correct.
+       */
+      FixInfacingNormals = 0x2000,
+
+      /**
+       * This step splits meshes with more than one primitive type in
+       * homogeneous submeshes.
+       *
+       * The step is executed after the triangulation step. After the step
+       * returns, just one bit is set in <code>aiMesh.mPrimitiveTypes</code>.
+       * This is especially useful for real-time rendering where point and line
+       * primitives are often ignored or rendered separately.
+       *
+       * You can use the <code>AI_CONFIG_PP_SBP_REMOVE</code> option to
+       * specify which primitive types you need. This can be used to easily
+       * exclude lines and points, which are rarely used, from the import.
+       */
+      SortByPType = 0x8000,
+
+      /**
+       * This step searches all meshes for degenerated primitives and converts
+       * them to proper lines or points.
+       *
+       * A face is »degenerated« if one or more of its points are identical.
+       * To have the degenerated stuff not only detected and collapsed but also
+       * removed, try one of the following procedures:
+       *
+       * <b>1.</b> (if you support lines and points for rendering but don't
+       *    want the degenerates)
+       * <ul>
+       *   <li>Specify the <code>FindDegenerates</code> flag.</li>
+       *   <li>Set the <code>AI_CONFIG_PP_FD_REMOVE</code> option to 1. This will
+       *       cause the step to remove degenerated triangles from the import
+       *       as soon as they're detected. They won't pass any further
+       *       pipeline steps.</li>
+       * </ul>
+       *
+       * <b>2.</b>(if you don't support lines and points at all ...)
+       * <ul>
+       *   <li>Specify the <code>FindDegenerates</code> flag.</li>
+       *   <li>Specify the <code>SortByPType</code> flag. This moves line and
+       *      point primitives to separate meshes.</li>
+       *   <li>Set the <code>AI_CONFIG_PP_SBP_REMOVE</codet> option to
+       *      <code>aiPrimitiveType_POINTS | aiPrimitiveType_LINES</code>
+       *      to cause SortByPType to reject point and line meshes from the
+       *      scene.</li>
+       * </ul>
+       *
+       * Note: Degenerated polygons are not necessarily bad and that's why
+       *    they're not removed by default. There are several file formats
+       *    which don't support lines or points. Some exporters bypass the
+       *    format specification and write them as degenerated triangle
+       *    instead.
+       */
+      FindDegenerates = 0x10000,
+
+      /**
+       * This step searches all meshes for invalid data, such as zeroed normal
+       * vectors or invalid UV coords and removes/fixes them. This is intended
+       * to get rid of some common exporter errors.
+       *
+       * This is especially useful for normals. If they are invalid, and the
+       * step recognizes this, they will be removed and can later be
+       * recomputed, e.g. by the <code>GenSmoothNormals</code> step.
+       *
+       * The step will also remove meshes that are infinitely small and reduce
+       * animation tracks consisting of hundreds if redundant keys to a single
+       * key. The <code>AI_CONFIG_PP_FID_ANIM_ACCURACY</code> config property
+       * decides the accuracy of the check for duplicate animation tracks.
+       */
+      FindInvalidData = 0x20000,
+
+      /**
+       * This step converts non-UV mappings (such as spherical or cylindrical
+       * mapping) to proper texture coordinate channels.
+       *
+       * Most applications will support UV mapping only, so you will probably
+       * want to specify this step in every case. Note tha Assimp is not always
+       * able to match the original mapping implementation of the 3d app which
+       * produced a model perfectly. It's always better to let the father app
+       * compute the UV channels, at least 3ds max, maja, blender, lightwave,
+       * modo, ... are able to achieve this.
+       *
+       * Note: If this step is not requested, you'll need to process the
+       *    <code>AI_MATKEY_MAPPING</code> material property in order to
+       *    display all assets properly.
+       */
+      GenUVCoords = 0x40000,
+
+      /**
+       * This step applies per-texture UV transformations and bakes them to
+       * stand-alone vtexture coordinate channelss.
+       *
+       * UV transformations are specified per-texture – see the
+       * <code>AI_MATKEY_UVTRANSFORM</code> material key for more information.
+       * This step processes all textures with transformed input UV coordinates
+       * and generates new (pretransformed) UV channel which replace the old
+       * channel. Most applications won't support UV transformations, so you
+       * will probably want to specify this step.
+       *
+       * Note: UV transformations are usually implemented in realtime apps by
+       *    transforming texture coordinates at vertex shader stage with a 3x3
+       *    (homogenous) transformation matrix.
+       */
+      TransformUVCoords = 0x80000,
+
+      /**
+       * This step searches for duplicate meshes and replaces duplicates with
+       * references to the first mesh.
+       *
+       * This step takes a while, don't use it if you have no time. Its main
+       * purpose is to workaround the limitation that many export file formats
+       * don't support instanced meshes, so exporters need to duplicate meshes.
+       * This step removes the duplicates again. Please note that Assimp does
+       * currently not support per-node material assignment to meshes, which
+       * means that identical meshes with differnent materials are currently
+       * <em>not</em> joined, although this is planned for future versions.
+       */
+      FindInstances = 0x100000,
+
+      /**
+       * A postprocessing step to reduce the number of meshes.
+       *
+       * In fact, it will reduce the number of drawcalls.
+       *
+       * This is a very effective optimization and is recommended to be used
+       * together with <code>OptimizeGraph</code>, if possible. The flag is
+       * fully compatible with both <code>SplitLargeMeshes</code> and
+       * <code>SortByPType</code>.
+       */
+      OptimizeMeshes = 0x200000,
+
+      /**
+       * A postprocessing step to optimize the scene hierarchy.
+       *
+       * Nodes with no animations, bones, lights or cameras assigned are
+       * collapsed and joined.
+       *
+       * Node names can be lost during this step. If you use special tag nodes
+       * to pass additional information through your content pipeline, use the
+       * <code>AI_CONFIG_PP_OG_EXCLUDE_LIST</code> setting to specify a list of
+       * node names you want to be kept. Nodes matching one of the names in
+       * this list won't be touched or modified.
+       *
+       * Use this flag with caution. Most simple files will be collapsed to a
+       * single node, complex hierarchies are usually completely lost. That's
+       * note the right choice for editor environments, but probably a very
+       * effective optimization if you just want to get the model data, convert
+       * it to your own format and render it as fast as possible.
+       *
+       * This flag is designed to be used with <code>OptimizeMeshes</code> for
+       * best results.
+       *
+       * Note: »Crappy« scenes with thousands of extremely small meshes packed
+       *    in deeply nested nodes exist for almost all file formats.
+       *    <code>OptimizeMeshes</code> in combination with
+       *    <code>OptimizeGraph</code> usually fixes them all and makes them
+       *    renderable.
+       */
+      OptimizeGraph  = 0x400000,
+
+      /** This step flips all UV coordinates along the y-axis and adjusts
+       * material settings and bitangents accordingly.
+       *
+       * Output UV coordinate system:
+       * <pre> 0y|0y ---------- 1x|0y
+       * |                 |
+       * |                 |
+       * |                 |
+       * 0x|1y ---------- 1x|1y</pre>
+       * You'll probably want to consider this flag if you use Direct3D for
+       * rendering. The <code>AI_PROCESS_CONVERT_TO_LEFT_HANDED</code> flag
+       * supersedes this setting and bundles all conversions typically required
+       * for D3D-based applications.
+      */
+      FlipUVs = 0x800000,
+
+      /**
+       * This step adjusts the output face winding order to be clockwise.
+       *
+       * The default face winding order is counter clockwise.
+       *
+       * Output face order:
+       * <pre>       x2
+       *
+       *                         x0
+       *  x1</pre>
+       */
+      FlipWindingOrder  = 0x1000000
+   }
+
+   /**
+    * Abbrevation for convenience.
+    */
+   alias aiPostProcessSteps aiProcess;
+
+   /**
+    * Shortcut flag for Direct3D-based applications.
+    *
+    * Combines the <code>MakeLeftHanded</code>, <code>FlipUVs</code> and
+    * <code>FlipWindingOrder</code> flags. The output data matches Direct3D's
+    * conventions: left-handed geometry, upper-left origin for UV coordinates
+    * and clockwise face order, suitable for CCW culling.
+    */
+   const aiPostProcessSteps AI_PROCESS_CONVERT_TO_LEFT_HANDED =
+      aiProcess.MakeLeftHanded |
+      aiProcess.FlipUVs |
+      aiProcess.FlipWindingOrder;
+
+   /**
+    * Default postprocess configuration optimizing the data for real-time rendering.
+    *
+    * Applications would want to use this preset to load models on end-user
+    * PCs, maybe for direct use in game.
+    *
+    * If you're using DirectX, don't forget to combine this value with
+    * the <code>ConvertToLeftHanded</code> step. If you don't support UV
+    * transformations in your application, apply the
+    * <code>TransformUVCoords</code> step, too.
+    *
+    * Note: Please take the time to read the doc for the steps enabled by this
+    *   preset. Some of them offer further configurable properties, some of
+    *   them might not be of use for you so it might be better to not specify
+    *   them.
+    */
+   const aiPostProcessSteps AI_PROCESS_PRESET_TARGET_REALTIME_FAST =
+      aiProcess.CalcTangentSpace |
+      aiProcess.GenNormals |
+      aiProcess.JoinIdenticalVertices |
+      aiProcess.Triangulate |
+      aiProcess.GenUVCoords |
+      aiProcess.SortByPType;
+
+    /**
+     * Default postprocess configuration optimizing the data for real-time
+     * rendering.
+     *
+     * Unlike <code>AI_PROCESS_PRESET_TARGET_REALTIME_FAST</code>, this
+     * configuration performs some extra optimizations to improve rendering
+     * speed and to minimize memory usage. It could be a good choice for a
+     * level editor environment where import speed is not so important.
+     *
+     * If you're using DirectX, don't forget to combine this value with
+     * the <code>ConvertToLeftHanded</code> step. If you don't support UV
+     * transformations in your application, apply the
+     * <code>TransformUVCoords</code> step, too.
+     *
+     * Note: Please take the time to read the doc for the steps enabled by this
+     *   preset. Some of them offer further configurable properties, some of
+     *   them might not be of use for you so it might be better to not specify
+     *   them.
+     */
+   const aiPostProcessSteps AI_PROCESS_PRESET_TARGET_REALTIME_QUALITY =
+      aiProcess.CalcTangentSpace |
+      aiProcess.GenSmoothNormals |
+      aiProcess.JoinIdenticalVertices |
+      aiProcess.ImproveCacheLocality |
+      aiProcess.LimitBoneWeights |
+      aiProcess.RemoveRedundantMaterials |
+      aiProcess.SplitLargeMeshes |
+      aiProcess.Triangulate |
+      aiProcess.GenUVCoords |
+      aiProcess.SortByPType |
+      aiProcess.FindDegenerates |
+      aiProcess.FindInvalidData;
+
+    /**
+     * Default postprocess configuration optimizing the data for real-time
+     * rendering.
+     *
+     * This preset enables almost every optimization step to achieve perfectly
+     * optimized data. It's your choice for level editor environments where
+     * import speed is not important.
+     *
+     * If you're using DirectX, don't forget to combine this value with
+     * the <code>ConvertToLeftHanded</code> step. If you don't support UV
+     * transformations in your application, apply the
+     * <code>TransformUVCoords</code> step, too.
+     *
+     * Note: Please take the time to read the doc for the steps enabled by this
+     *   preset. Some of them offer further configurable properties, some of
+     *   them might not be of use for you so it might be better to not specify
+     *   them.
+     */
+   const aiPostProcessSteps AI_PROCESS_PRESET_TARGET_REALTIME_MAX_QUALITY =
+      AI_PROCESS_PRESET_TARGET_REALTIME_QUALITY |
+      aiProcess.FindInstances |
+      aiProcess.ValidateDataStructure |
+      aiProcess.OptimizeMeshes;
+}