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Open Asset Import Library - Java Binding (jassimp)
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*/
package jassimp;

import java.util.Set;

/**
 * Enumerates the post processing steps supported by assimp.
 */
public enum AiPostProcessSteps {

    /**
     * Calculates the tangents and bitangents for the imported meshes.
     * <p>
     * 
     * 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's a
     * config setting, <tt>#AI_CONFIG_PP_CT_MAX_SMOOTHING_ANGLE</tt>, which
     * allows you to specify a maximum smoothing angle for the algorithm.
     * However, usually you'll want to leave it at the default value.
     */
    CALC_TANGENT_SPACE(0x1),


    /**
     * Identifies and joins identical vertex data sets within all imported
     * meshes.<p>
     * 
     * After this step is run, each mesh contains unique vertices, so a vertex
     * may be 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'll just waste rendering time. <b>If this flag
     * is not specified</b>, no vertices are referenced by more than one face
     * and <b>no index buffer is required</b> for rendering.
     */
    JOIN_IDENTICAL_VERTICES(0x2),


    /**
     * Converts all the imported data to a left-handed coordinate space.<p>
     * 
     * By default the data is returned in a right-handed coordinate space (which
     * OpenGL prefers). In this space, +X points to the right, +Z points towards
     * the viewer, and +Y points upwards. In the DirectX coordinate space +X
     * points to the right, +Y points upwards, and +Z points away from the
     * viewer.<p>
     * 
     * You'll probably want to consider this flag if you use Direct3D for
     * rendering. The #ConvertToLeftHanded flag supersedes this
     * setting and bundles all conversions typically required for D3D-based
     * applications.
     */
    MAKE_LEFT_HANDED(0x4),


    /**
     * Triangulates all faces of all meshes.<p>
     * 
     * 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 faces with more than 3 indices into
     * triangles. Line and point primitives are *not* modified! If you want
     * 'triangles only' with no other kinds of primitives, try the following
     * solution:
     * <ul>
     *   <li>Specify both #Triangulate and #SortByPType
     *   <li>Ignore all point and line meshes when you process assimp's output
     * </ul>
     */
    TRIANGULATE(0x8),


    /**
     * Removes some parts of the data structure (animations, materials, light
     * sources, cameras, textures, vertex components).<p>
     * 
     * The components to be removed are specified in a separate configuration
     * option, <tt>#AI_CONFIG_PP_RVC_FLAGS</tt>. This is quite useful if you
     * don't need all parts of the output structure. Vertex colors are rarely
     * used today for example... Calling this step to remove unneeded data from
     * the pipeline as early as possible results in increased performance and a
     * more optimized output data structure. This step is also useful if you
     * want to force Assimp to recompute normals or tangents. The corresponding
     * steps don't recompute them if they're already there (loaded from the
     * source asset). By using this step you can make sure they are NOT there.
     * <p>
     * 
     * 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, and it has per-face vertex colors. Vertex positions can't
     * be shared, thus the #JoinIdenticalVertices step fails to
     * optimize the data because of these nasty little vertex colors. Most apps
     * don't even process them, so it's all for nothing. By using this step,
     * unneeded components are excluded as early as possible thus opening more
     * room for internal optimizations.
     */
    REMOVE_COMPONENT(0x10),


    /**
     * Generates normals for all faces of all meshes.<p>
     * 
     * This is ignored if normals are already there at the time this flag is
     * evaluated. Model importers try to load them from the source file, so
     * they're usually already there. Face normals are shared between all points
     * of a single face, so a single point can have multiple normals, which
     * forces the library to duplicate vertices in some cases.
     * #JoinIdenticalVertices is *senseless* then.<p>
     * 
     * This flag may not be specified together with {@link #GEN_SMOOTH_NORMALS}.
     */
    GEN_NORMALS(0x20),


    /**
     * Generates smooth normals for all vertices in the mesh.<p>
     * 
     * This is ignored if normals are already there at the time this flag is
     * evaluated. Model importers try to load them from the source file, so
     * they're usually already there.<p>
     * 
     * This flag may not be specified together with {@link #GEN_NORMALS}
     * There's a configuration option,
     * <tt>#AI_CONFIG_PP_GSN_MAX_SMOOTHING_ANGLE</tt> 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 degrees) results in very
     * good visual appearance.
     */
    GEN_SMOOTH_NORMALS(0x40),


    /**
     * Splits large meshes into smaller sub-meshes.<p>
     * 
     * This is quite useful for real-time rendering, where the number of
     * triangles which can be maximally processed in a single draw-call is
     * 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.<p>
     * 
     * The split limits can (and should!) be set through the
     * <tt>#AI_CONFIG_PP_SLM_VERTEX_LIMIT</tt> and
     * <tt>#AI_CONFIG_PP_SLM_TRIANGLE_LIMIT</tt> settings. The default values
     * are <tt>#AI_SLM_DEFAULT_MAX_VERTICES</tt> and
     * <tt>#AI_SLM_DEFAULT_MAX_TRIANGLES</tt>.<p>
     * 
     * Note that splitting is generally a time-consuming task, but only if
     * there's something to split. The use of this step is recommended for most
     * users.
     */
    SPLIT_LARGE_MESHES(0x80),


    /**
     * Removes the node graph and pre-transforms all vertices with the local
     * transformation matrices of their nodes.<p>
     * 
     * The output scene still contains nodes, however there is only a root node
     * with children, each one referencing only one mesh, and 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 without a scenegraph. The step CAN 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.<p>
     * 
     * <b>Note:</b> The <tt>#AI_CONFIG_PP_PTV_NORMALIZE</tt> configuration 
     * property can be set to normalize the scene's spatial dimension to the 
     * -1...1 range.
     */
    PRE_TRANSFORM_VERTICES(0x100),


    /**
     * Limits the number of bones simultaneously affecting a single vertex to a
     * maximum value.<p>
     * 
     * If any vertex is affected by more than the maximum 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 (defined as <tt>#AI_LMW_MAX_WEIGHTS</tt>
     * in config.h), but you can use the <tt>#AI_CONFIG_PP_LBW_MAX_WEIGHTS</tt>
     * setting to supply your own limit to the post processing step.<p>
     * 
     * If you intend to perform the skinning in hardware, this post processing
     * step might be of interest to you.
     */
    LIMIT_BONE_WEIGHTS(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.<p>
     * 
     * It is recommended that you capture Assimp's log output if you use this
     * flag, so you can easily find out what's wrong if a file fails the
     * validation. The validator is quite strict and will find *all*
     * inconsistencies in the data structure... It is recommended that plugin
     * developers 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. #Importer::GetErrorString() or #aiGetErrorString() carry
     * the error message around.</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, <tt>#AI_SCENE_FLAGS_VALIDATION_WARNING</tt> is set in
     * #aiScene::mFlags</li>
     * </ul>
     * 
     * This post-processing step is not time-consuming. Its use is not
     * compulsory, but recommended.
     */
    VALIDATE_DATA_STRUCTURE(0x400),


    /**
     * Reorders triangles for better vertex cache locality.<p>
     * 
     * 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 <a href="
     * http://www.cs.princeton.edu/gfx/pubs/Sander_2007_%3ETR/tipsy.pdf">this
     * paper</a>).<p>
     * 
     * If you intend to render huge models in hardware, this step might be of
     * interest to you. The <tt>#AI_CONFIG_PP_ICL_PTCACHE_SIZE</tt>config
     * setting can be used to fine-tune the cache optimization.
     */
    IMPROVE_CACHE_LOCALITY(0x800),


    /**
     * Searches for redundant/unreferenced materials and removes them.<p>
     * 
     * This is especially useful in combination with the
     * #PretransformVertices and #OptimizeMeshes 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 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.<p>
     * 
     * Several material settings not contributing to the final appearance of a
     * surface are ignored in all comparisons (e.g. the material name). So, if
     * you're passing additional information through the content pipeline
     * (probably using *magic* material names), don't specify this flag.
     * Alternatively take a look at the <tt>#AI_CONFIG_PP_RRM_EXCLUDE_LIST</tt>
     * setting.
     */
    REMOVE_REDUNDANT_MATERIALS(0x1000),


    /**
     * This step tries to determine which meshes have normal vectors that are
     * facing inwards and inverts them.<p>
     * 
     * The algorithm is simple but effective: the bounding box of all vertices +
     * 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.
     */
    FIX_INFACING_NORMALS(0x2000),


    /**
     * This step splits meshes with more than one primitive type in homogeneous
     * sub-meshes.<p>
     * 
     * The step is executed after the triangulation step. After the step
     * returns, just one bit is set in aiMesh::mPrimitiveTypes. This is
     * especially useful for real-time rendering where point and line primitives
     * are often ignored or rendered separately. You can use the
     * <tt>#AI_CONFIG_PP_SBP_REMOVE</tt> 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.
     */
    SORT_BY_PTYPE(0x8000),


    /**
     * This step searches all meshes for degenerate primitives and converts them
     * to proper lines or points.<p>
     * 
     * A face is 'degenerate' if one or more of its points are identical. To
     * have the degenerate stuff not only detected and collapsed but removed,
     * try one of the following procedures: <br>
     * <b>1.</b> (if you support lines and points for rendering but don't want
     * the degenerates)</br>
     * <ul>
     * <li>Specify the #FindDegenerates flag.</li>
     * <li>Set the <tt>AI_CONFIG_PP_FD_REMOVE</tt> option to 1. This will cause
     * the step to remove degenerate triangles from the import as soon as
     * they're detected. They won't pass any further pipeline steps.</li>
     * </ul>
     * <br>
     * <b>2.</b>(if you don't support lines and points at all)</br>
     * <ul>
     *   <li>Specify the #FindDegenerates flag.
     *   <li>Specify the #SortByPType flag. This moves line and point 
     *       primitives to separate meshes.
     *   <li>Set the <tt>AI_CONFIG_PP_SBP_REMOVE</tt> option to
     *       <code>aiPrimitiveType_POINTS | aiPrimitiveType_LINES</code>
     *       to cause SortByPType to reject point and line meshes from the 
     *       scene.
     * </ul>
     * <b>Note:</b> Degenerated polygons are not necessarily evil and that's 
     * why they're not removed by default. There are several file formats 
     * which don't support lines or points, and some exporters bypass the 
     * format specification and write them as degenerate triangles instead.
     */
    FIND_DEGENERATES(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.<p>
     * 
     * This is especially useful for normals. If they are invalid, and the step
     * recognizes this, they will be removed and can later be recomputed, i.e.
     * by the {@link #GEN_SMOOTH_NORMALS} flag.<p>
     * 
     * 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 <tt>AI_CONFIG_PP_FID_ANIM_ACCURACY</tt> config property decides
     * the accuracy of the check for duplicate animation tracks.
     */
    FIND_INVALID_DATA(0x20000),


    /**
     * This step converts non-UV mappings (such as spherical or cylindrical
     * mapping) to proper texture coordinate channels.<p>
     * 
     * Most applications will support UV mapping only, so you will probably want
     * to specify this step in every case. Note that 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 modelling app compute
     * the UV channels - 3ds max, Maya, Blender, LightWave, and Modo do this for
     * example.<p>
     * 
     * <b>Note:</b> If this step is not requested, you'll need to process the
     * <tt>MATKEY_MAPPING</tt> material property in order to display all 
     * assets properly.
     */
    GEN_UV_COORDS(0x40000),


    /**
     * This step applies per-texture UV transformations and bakes them into
     * stand-alone vtexture coordinate channels.<p>
     * 
     * UV transformations are specified per-texture - see the
     * <tt>MATKEY_UVTRANSFORM</tt> material key for more information. This
     * step processes all textures with transformed input UV coordinates and
     * generates a new (pre-transformed) UV channel which replaces the old
     * channel. Most applications won't support UV transformations, so you will
     * probably want to specify this step.<p>
     * 
     * <b>Note:</b> UV transformations are usually implemented in real-time 
     * apps by transforming texture coordinates at vertex shader stage with a 
     * 3x3 (homogenous) transformation matrix.
     */
    TRANSFORM_UV_COORDS(0x80000),


    /**
     * This step searches for duplicate meshes and replaces them with references
     * to the first mesh.<p>
     * 
     * This step takes a while, so don't use it if speed is a concern. Its main
     * purpose is to workaround the fact 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 not
     * currently support per-node material assignment to meshes, which means
     * that identical meshes with different materials are currently *not*
     * joined, although this is planned for future versions.
     */
    FIND_INSTANCES(0x100000),


    /**
     * A postprocessing step to reduce the number of meshes.<p>
     * 
     * This will, in fact, reduce the number of draw calls.<p>
     * 
     * This is a very effective optimization and is recommended to be used
     * together with #OptimizeGraph, if possible. The flag is fully
     * compatible with both {@link #SPLIT_LARGE_MESHES} and 
     * {@link #SORT_BY_PTYPE}.
     */
    OPTIMIZE_MESHES(0x200000),


    /**
     * A postprocessing step to optimize the scene hierarchy.<p>
     * 
     * Nodes without animations, bones, lights or cameras assigned are collapsed
     * and joined.<p>
     * 
     * Node names can be lost during this step. If you use special 'tag nodes'
     * to pass additional information through your content pipeline, use the
     * <tt>#AI_CONFIG_PP_OG_EXCLUDE_LIST</tt> 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.<p>
     * 
     * Use this flag with caution. Most simple files will be collapsed to a
     * single node, so complex hierarchies are usually completely lost. This is
     * not useful 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.<p>
     * 
     * This flag is designed to be used with #OptimizeMeshes for best
     * results.<p>
     * 
     * <b>Note:</b> 'Crappy' scenes with thousands of extremely small meshes 
     * packed in deeply nested nodes exist for almost all file formats.
     * {@link #OPTIMIZE_MESHES} in combination with {@link #OPTIMIZE_GRAPH}
     * usually fixes them all and makes them renderable.
     */
    OPTIMIZE_GRAPH(0x400000),


    /**
     * This step flips all UV coordinates along the y-axis and adjusts material
     * settings and bitangents accordingly.<p>
     * 
     * <b>Output UV coordinate system:</b><br>
     * <code><pre>
     * 0y|0y ---------- 1x|0y 
     *   |                | 
     *   |                |
     *   |                | 
     * 0x|1y ---------- 1x|1y
     * </pre></code>
     * <p>
     *          
     * You'll probably want to consider this flag if you use Direct3D for 
     * rendering. The {@link #MAKE_LEFT_HANDED} flag supersedes this setting 
     * and bundles all conversions typically required for D3D-based 
     * applications.
     */
    FLIP_UVS(0x800000),


    /**
     * This step adjusts the output face winding order to be CW.<p>
     * 
     * The default face winding order is counter clockwise (CCW).
     * 
     * <b>Output face order:</b>
     * 
     * <code><pre>
     *        x2
     * 
     *                      x0 
     *  x1
     * </pre></code>
     */
    FLIP_WINDING_ORDER(0x1000000),


    /**
     * This step splits meshes with many bones into sub-meshes so that each
     * sub-mesh has fewer or as many bones as a given limit.<p>
     */
    SPLIT_BY_BONE_COUNT(0x2000000),


    /**
     * This step removes bones losslessly or according to some threshold.<p>
     * 
     * In some cases (i.e. formats that require it) exporters are forced to
     * assign dummy bone weights to otherwise static meshes assigned to animated
     * meshes. Full, weight-based skinning is expensive while animating nodes is
     * extremely cheap, so this step is offered to clean up the data in that
     * regard.<p>
     * 
     * Use <tt>#AI_CONFIG_PP_DB_THRESHOLD</tt> to control this. Use
     * <tt>#AI_CONFIG_PP_DB_ALL_OR_NONE</tt> if you want bones removed if and
     * only if all bones within the scene qualify for removal.
     */
    DEBONE(0x4000000);

    
    /**
     * Utility method for converting to c/c++ based integer enums from java 
     * enums.<p>
     * 
     * This method is intended to be used from JNI and my change based on
     * implementation needs.
     * 
     * @param set the set to convert
     * @return an integer based enum value (as defined by assimp) 
     */
    static long toRawValue(Set<AiPostProcessSteps> set) {
        long rawValue = 0L;
        
        for (AiPostProcessSteps step : set) {
            rawValue |= step.m_rawValue;
        }
        
        return rawValue;
    }
    
    
    /**
     * Constructor.
     * 
     * @param rawValue maps java enum to c/c++ integer enum values
     */
    private AiPostProcessSteps(long rawValue) {
        m_rawValue = rawValue;
    }

    
    /**
     * The mapped c/c++ integer enum value.
     */
    private final long m_rawValue;
}
