# vsp::VizStreamerProxy - C++ Proxy Class

The VizStreamerProxy class is a C++ interface that sends visualization data to the HOOPS Envision for Web Visualization Streamer Service backend. It simplifies usage by hiding the lower-level gRPC calls behind user-friendly C++ methods.

The VizStreamerProxy class defines a pure virtual interface to the proxy. It is defined in the vsp namespace.

We provide a vsp::grpc_impl::VizStreamerProxyGrpc class implementing this interface for a gRPC connection. After creating the object, use the connectToService() method to connect to the Visualization Streamer Service. After a successful connection, the proxy is ready to use.

    const std::string serverAddress = "localhost:50051";
    auto connStatus = proxy.connectToService(serverAddress, true);
    if (!connStatus.ok())
        return EXIT_FAILURE;
    }
    std::cout << "Proxy has connected to service" << std::endl;

Below, you find documentation on all the methods of the proxy. For an introduction and more general documentation of how the Visualization Streamer Service works, please see Overview.

Note

In the subsequent chapter, any reference to the Service means the Visualization Streamer Service.

## Expected and Status

`Expected` is a templated class that can either hold a given DataType or an error if something goes wrong. If `Expected::ok()` returns true, it holds a value of the given DataType. If false, it holds an error message.

Example usage

    const vsp::ExpectedKey eMeshKey =
       m_proxy->pushIndexedPolygonMesh(vertexArr, vertsPerPolyArr, indexArr);
    if (!eMeshKey.ok())
    {
        return eMeshKey.errorMessage();
    }

    vsp::MeshInstance instance;
    instance.meshKey = eMeshKey.value();

`Status` is similar to `Expected` but just with a boolean type. So it has the `ok()` method and the `errorMessage()` method, but not the `value()` method, as this is sort of returned by `ok()`.

### ResourceKey

A `ResourceKey` is an object identifier referencing a data/instance object stored in the Service. All the `pushXX()` methods and the `addXXGroup()` methods return a `ResourceKey` and this key is used to reference the data in the Instances or the Frames.

    using ResourceKey = std::string;
    using ExpectedKey = Expected<ResourceKey>;

So `ExpectedKey` is either a `ResourceKey` or an error object.

### Tags

Meshes, Point Clouds, Particle Traces and Textures have an optional user-defined tag (std::string) that can be specified when the data is pushed. This tag is not used by the Service but can be retrieved in the client side Stream Model.

## Documentation

### pushIndexedPolygonMesh

    virtual ExpectedKey pushIndexedPolygonMesh(
        const std::vector<float>& vertexArr,
        const std::vector<vsp::ubyte>& verticesPerPolyArr,
        const std::vector<vsp::uint>& indexArr,
        std::string tag = "",
        const OptionalMeshData& optionalMeshData = OptionalMeshData()
    ) = 0;

Sends a polygon mesh with a varying number of vertices per polygon to the Service. The polygons can have two or more vertices but must be convex for proper rendering. The polygon will rendered according to the specified MeshSettings.

- Parameters:
  - vertexArr: A list of float coordinates (x, y, z).
  - verticesPerPolyArr: Number of vertices for each polygon.
  - indexArr: Defining the polygons. Indices into the vertexArr.
  - tag: A user-defined optional tag. Not used by the Service but can be retrieved in the client side Stream Model
  - optionalMeshData: Optional per-polygon and per-vertex user-defined ids. Not used by the Service but can be retrieved in the client side Stream Model.

### pushIndexedSingleTypePolygonMesh

    virtual ExpectedKey pushIndexedSingleTypePolygonMesh(
        const std::vector<float>& vertexArr,
        vsp::ubyte fixedVerticesPerPoly,
        const std::vector<vsp::uint>& indexArr,
        std::string tag = "",
        const OptionalMeshData& optionalMeshData = OptionalMeshData()
    ) = 0;

Sends a polygon mesh with a fixed number of vertices per polygon to the Service. The polygons can have two or more vertices but must be convex for proper rendering. The polygon will rendered according to the specified MeshSettings.

- Parameters:
  - vertexArr: A list of float coordinates (x, y, z).
  - fixedVerticesPerPoly: The number of vertices per polygon in the mesh.
  - indexArr: Defining the polygons. Indices into the vertexArr.
  - tag: A user-defined optional tag. Not used by the Service but can be retrieved in the client side Stream Model
  - optionalMeshData: Optional per-polygon and per-vertex user-defined ids. Not used by the Service but can be retrieved in the client side Stream Model

### pushMeshScalar

    virtual ExpectedKey pushMeshScalar(
        ResourceKey bindToMeshKey,
        ResultMapping resultMapping,
        const std::vector<float>& valueArr
    ) = 0;

Sends an array of scalar results (1D field) that can be mapped to a Mesh to the Service.

- Parameters:
  - bindToMeshKey: The ResourceKey of the the Mesh object (returned by `pushIndexedPolygonMesh()` or `pushIndexedSingleTypePolygonMesh()`)
  - resultMapping: The result mapping for the valueArr. Can be per vertex, per polygon, per polygon-vertex.
  - valueArr: One scalar result value per vertex, polygon or polygon-vertex in the Mesh.

### pushMeshVector

    virtual ExpectedKey pushMeshVector(
        ResourceKey bindToMeshKey,
        ResultMapping resultMapping,
        const std::vector<float>& vectorArr
    ) = 0;

Sends an array of vector results (3D field) that can be mapped to a Mesh to the Service.

- Parameters:
  - bindToMeshKey: The ResourceKey of the the Mesh object (returned by `pushIndexedPolygonMesh()` or `pushIndexedSingleTypePolygonMesh()`)
  - resultMapping: The result mapping for the vectorArr. Can be per vertex, per polygon, per polygon-vertex.
  - vectorArr: One vector result (x,y,z) value per vertex, polygon or polygon-vertex in the Mesh.

### pushMeshDisplacement

    virtual ExpectedKey pushMeshDisplacement(
        ResourceKey bindToMeshKey,
        const std::vector<float>& displacementArr
    ) = 0;

Sends an array of displacement results (x,y,z) that can be mapped to a Mesh to the Service.

- Parameters:
  - bindToMeshKey: The ResourceKey of the the Mesh object (returned by `pushIndexedPolygonMesh()` or `pushIndexedSingleTypePolygonMesh()`)
  - displacementArr: One displacement vector (x,y,z) per vertex in the mesh in the Mesh. The nodes in the mesh will be displaced with the given values.

### pushPointCloud

    virtual ExpectedKey pushPointCloud(
        const std::vector<float>& vertexArr,
        std::string tag = ""
    ) = 0;

Sends an array of points to the Service. The point cloud can be visualized as points but can also have vector results at each point to allow for visualization of vector arrows not tied to a mesh.

- Parameters:
  - vertexArr: Array with 3D coordinates (x,y,z) for the points.
  - tag: A user-defined optional tag. Not used by the Service but can be retrieved in the client side Stream Model.

### pushPointCloudVector

    virtual ExpectedKey pushPointCloudVector(
        ResourceKey bindToPointCloudKey,
        const std::vector<float>& vectorArr
    ) = 0;

Sends an array of vector results (3D field) that can be mapped on a Point Cloud to the Service.

- Parameters:
  - bindToPointCloudKey: The ResourceKey of the the Point Cloud object (returned by `pushPointCloud()`)
  - vectorArr: One vector result (x,y,z) value per point in the Point Cloud

### pushPointCloudScalar

    virtual ExpectedKey pushPointCloudScalar(
        ResourceKey bindToPointCloudKey,
        const std::vector<float>& valueArr
    ) = 0;

Sends an array of scalar results (1D field) that can be mapped on a Point Cloud to the Service.

- Parameters:
  - bindToPointCloudKey: The ResourceKey of the the Point Cloud object (returned by `pushPointCloud()`)
  - valueArr: One scalar result value per point in the Point Cloud

### pushPointCloudColors

    virtual ExpectedKey pushPointCloudColors(
        ResourceKey bindToPointCloudKey,
        const std::vector<ubyte>& rgbByteColorArr
    ) = 0;

Sends an array of rgb byte colors per point in a Point Cloud to the Service.

- Parameters:
  - bindToPointCloudKey: The ResourceKey of the the Point Cloud object (returned by `pushPointCloud()`)
  - rgbByteColorArr: Array of byte colors (r,g,b) per point in the Point Cloud

### pushParticleTrace

    virtual ExpectedKey pushParticleTrace(
        const std::vector<float>& positionArr,
        const std::vector<float>& timeStampArr,
        std::string tag = "",
        const OptionalParticleTraceData& optionalParticleTraceData = OptionalParticleTraceData()
    ) = 0;

Sends particle trace data to the Service.

- Parameters:
  - positionArr: 3D coordinates of the points on the particle trace (x,y,z)
  - timeStampArr: Array of time stamps for each 3D coordinate (used to animate)
  - tag: A user-defined optional tag. Not used by the Service but can be retrieved in the client side Stream Model
  - optionalParticleTraceData: Optional scalar result per point in the particle trace (can be used for color mapping).

### pushTexture

    virtual ExpectedKey pushTexture(
        ushort imageWidth,
        ushort imageHeight,
        const std::vector<ubyte>& pixelRgbaArr,
        const TextureOptions& textureOptions,
        std::string tag = ""
    ) = 0;

Sends a 2D texture image to the Service. The texture can be mapped on a Mesh surface.

- Parameters:
  - imageWidth: The width of the texture
  - imageHeight: The height of the texture
  - pixelRgbaArr: 3D coordinates of the points on the particle trace (x,y,z)
  - textureOptions: Options for the texture mapping: min and mag filter, wrap mode and environment mapping.
  - tag: A user-defined optional tag. Not used by the Service but can be retrieved in the client side Stream Model

### pushMeshTextureCoords

    virtual ExpectedKey pushMeshTextureCoords(
        ResourceKey bindToMeshKey,
        ResultMapping resultMapping,
        const std::vector<float>& textureCoord2dArr
    ) = 0;

Sends an array if 2D texture coordinates (s, t) to the Service. The array mush have one texture coordinate per vertex in the associated mesh.

- Parameters:
  - bindToMeshKey: The ResourceKey of the the Mesh object (returned by `pushIndexedPolygonMesh()` or `pushIndexedSingleTypePolygonMesh()`)
  - resultMapping: The result mapping for the (s,t) coordinates in textureCoord2dArr. Can be per vertex, per polygon, per polygon-vertex.
  - textureCoord2dArr: Array of 2D texture coordinates (s,t) per vertex, polygon or polygon vertex in the Mesh.

### pushTransformArray

    virtual ExpectedKey pushTransformArray(
        const std::vector<float>& matrixArr
    ) = 0;

Sends an array of 4x4 Transformation Matrices to the Service. The matrices can be referenced in Mesh Instances and be used to do rigid body transformations (either for animations or for instancing). Matrices are specified as 16 floats in row, column order:

    | m00  m01  m02  m03 |     | 0  4   8  12 |
    | m10  m11  m12  m13 |     | 1  5   9  13 |
    | m20  m21  m22  m23 |     | 2  6  10  14 |
    | m30  m31  m32  m33 |     | 3  7  11  15 |

This is consistent with the way matrices are represented in OpenGL. To exemplify, translation values are stored in elements 12,13,14; see figure below:

    | 1  0  0 Tx |
    | 0  1  0 Ty |
    | 0  0  1 Tz |
    | 0  0  0  1 |

### pushMeshSettings

    virtual ExpectedKey pushMeshSettings(
        const MeshSettings& settings
    ) = 0;

Sends settings to describe how to render the Mesh to the Service. The mesh settings consist of draw style (surface, surface mesh, surface outline mesh, lines, points, outline, hidden lines removed), color, opacity (1.0 opaque, 0.0 fully transparent (invisible)) and smooth (per-vertex)/flat (per polygon) shading.

The settings will be mapped to a Mesh in the Mesh Instance object.

### pushPointCloudSettings

    virtual ExpectedKey pushPointCloudSettings(
        const PointCloudSettings& settings
    ) = 0;

Sends settings to describe how to render the Point Cloud to the Service. The settings consists of a single color for all points.

The settings will be mapped to a Point Cloud in the Point Cloud Instance object.

### pushScalarSettings

    virtual ExpectedKey pushScalarSettings(
        const ScalarSettings& settings
    ) = 0;

Sends Scalar settings to the Service. The scalar settings describe how to visualize the mapped Scalar result on a Mesh. The settings include the minimum and maximum range for the color mapping. More settings will be added.

### pushVectorSettings

    virtual ExpectedKey pushVectorSettings(
        const VectorSettings& settings
    ) = 0;

Sends Vector settings to the Service. The vector settings describe how to visualize the vector result. The settings include a single color and a scalar factor. More settings will be added.

### pushParticleTraceSettings

    virtual ExpectedKey pushParticleTraceSettings(
        const ParticleTraceSettings& settings
    ) = 0;

Sends Particle Trace settings to the Service. The particle trace settings describe how to render the particle traces. This includes settings for visualization style (comets, spheres, cylinders), color, radius, settings for animation.

### addMeshGroup

    virtual ExpectedKey addMeshGroup(
        const std::vector<MeshInstance>& instanceArr
    ) = 0;

Sends a mesh instance description to the Service. The MeshInstance specifies an instance/configuration of a mesh: ResourceKeys for Mesh and MeshSettings, which Scalar to map on the surface (and its settings), which Vector result to map on the surface (and its settings) (can be more than one), texture and settings, transform array ResourceKey and the index of the matrix to use for this mesh.

    struct MeshInstance
    {
        ResourceKey                     meshKey;
        ResourceKey                     meshSettingsKey;

        std::optional<ResourceKey>      mapScalarKey;
        std::optional<ResourceKey>      mapScalarSettingsKey;
        std::optional<ResourceKey>      textureKey;
        std::optional<ResourceKey>      textureCoordsKey;
        std::vector<MeshVectorInstance> vectorInstanceArr;

        std::optional<ResourceKey>      transformArrayKey;
        int                             transformArrayIndex = 0;

        std::optional<ResourceKey>      parentMeshGroupKey;
        std::optional<std::string>      tag;
    };

A meshKey and meshSettingsKey must always be specified.

For color mapping of the mesh, one of the following combinations must be specified

- mapScalarKey + mapScalarSettingsKey can be used to map a scalar field to the mesh.
- textureKey + textureCoordsKey can be used to add a texture to the mesh. Texture coords are 2D coords per vertex.

Any number of vector fields can be mapped onto the mesh as specified in the vectorInstanceArr, each defined by a MeshVectorSpec.

You can also specify a `parentMeshGroupKey`, which indicates that this group is dependent on another mesh group (will not be visualized on the client until both are ready). This is useful if you have e.g. a custom element mesh provided as lines in this group, but would not like it to show up before the associated Mesh with the surface polygons.

### addPointCloudGroup

    virtual ExpectedKey addPointCloudGroup(
        const std::vector<PointCloudInstance>& instanceArr
    ) = 0;

Sends a point cloud instance description to the Service. The PointCloudInstance specifies an instance/configuration of a point cloud: ResourceKeys for PointCloud and PointCloudSettings, Vector and VectorSettings, Scalar and ScalarSettings and Colors for per-point/vector coloring.

    struct PointCloudInstance
    {
        ResourceKey                     pointCloudKey;
        ResourceKey                     pointCloudSettingsKey;

        std::optional<ResourceKey>      mapScalarKey;
        std::optional<ResourceKey>      mapScalarSettingsKey;
        std::optional<ResourceKey>      colorsKey;
        std::optional<ResourceKey>      vectorKey;
        std::optional<ResourceKey>      vectorSettingsKey;

        std::optional<ResourceKey>      parentMeshGroupKey;
        std::optional<std::string>      tag;
    };

A pointCloudKey and pointCloudSettingsKey must always be specified.

For color mapping of the points/vectors, one of the following combinations must be specified

- mapScalarKey + mapScalarSettingsKey can be used to map a scalar field to the mesh.
- colorsKey can be used to specify one RGB color per point/vector.

If the point cloud should show vectors, you need to specify both a vectorKey and a vectorSettingsKey.

You can also specify a `parentMeshGroupKey`, which indicates that this PointCloud is dependent on a mesh group (will not be visualized on the client until both are ready). This is useful if you have e.g. regular sampled vectors on a cutting plane, but would not like the vectors to show up before the associated Mesh with the surface polygons.

### addParticleTraceGroup

    virtual ExpectedKey addParticleTraceGroup(
        const std::vector<ResourceKey>& particleTraceKeyArr,
        ResourceKey particleTraceSettingsKey
    ) = 0;

Sends a particle trace group instance to the Service. This allows you to specify an array of ResourceKeys for ParticleTrace and a single ResourceKey for the ParticleTraceSettings. These settings will be shared by all ParticleTraces in this instance.

### createStream

    virtual Status createStream(
        std::string streamName,
        std::string description
    ) = 0;

Create a stream with the given streamName and a description. You need at least one stream to use the Service.

See description of Stream in Overview.

### deleteStream

    virtual Status deleteStream(
        std::string streamName
    ) = 0;

Delete the stream with the given streamName. This will delete all Frames associated with the stream and can allow for memory cleanup of unreferenced objects using the `deleteUnreferencedData()` method.

### createAndPublishSingleFrame

    virtual ExpectedKey createAndPublishSingleFrame(
        std::string streamName,
        const Frame& frame
    ) = 0;

Convenience function for creating and publishing a single frame in one call, returns the resource key of the frame.

Similar to `createFrame()`, this function is a server-side barrier that does not return until the frame is ready to stream from the server.

The function does the following:

> - Deletes all existing frames (deleteAllFrames(streamName))
> - Creates a new frame (createFrame(streamName, frame))
> - Shows/publishes the single frame (publishFrames(streamName, [frame]))

### createFrame

    virtual ExpectedKey createFrame(
        std::string streamName,
        const Frame& frame
    ) = 0;

Create a Frame in the given Stream with the name streamName. The Frame struct has an array of ResourceKeys for MeshInstances, PointCloudInstances and ParticleTraceInstances.

    struct Frame
    {
        std::vector<ResourceKey>    meshGroupKeyArr;
        std::vector<ResourceKey>    pointCloudGroupKeyArr;
        std::vector<ResourceKey>    particleTraceGroupKeyArr;
    };

createFrame() is a server-side barrier that does not return until the Frame is ready to stream from the server.

### publishFrames

    virtual Status publishFrames(
        std::string streamName,
        const std::vector<ResourceKey>& frameKeyArr
    ) = 0;

Publish the Frames with the ResourceKeys specified in the frameKeyArr on the Stream with the name streamName. Unless you have transient animations, you will only include one Frame (one ResourceKey) in the frameKeyArr.

PublishFrame(s) tells all the client side Stream Model connected to the given streamName to show the given Frame(s). The Frames are already processed (as createFrame is a server-side barrier) so this just tells the client models to show the given Frame(s). The client will then fetch any data not already in the client and progressively update the rendering until it is complete.

Calling publishFrames() will replace any previously published Frames, so you need to include all Frames that should be shown.

### deleteFrames

    virtual Status deleteFrames(
        std::string streamName,
        const std::vector<ResourceKey>& frameKeyArr
    ) = 0;

Delete the specified Frames with the ResourceKeys in frameKeyArr. This will remove the Frame specifications from the Service and make it possible to clean up any unreferenced data (by using the `deleteUnreferencedData()` method).

### deleteAllFrames

    virtual Status deleteAllFrames(
        std::string streamName
    ) = 0;

Removes all frames from a specific stream. This will make it possible to clean up any unreferenced data (by using the `deleteUnreferencedData()` method).

### deleteUnreferencedData

    virtual Status deleteUnreferencedData() = 0;

This method will delete any data objects that are not referenced (directly or indirectly) by the current list of Frames in any of the current Streams.

We will add more fine-grained control for garbage collection and memory management in later versions of the product.

## Not Implemented

The following methods are not implemented in the VizStreamerProxy class:

### pushPointCloudScalar

    virtual ExpectedKey pushPointCloudScalar(
        ResourceKey bindToPointCloudKey,
        const std::vector<float>& valueArr
    ) = 0;

### pushPointCloudColors

    virtual ExpectedKey pushPointCloudColors(
        ResourceKey bindToPointCloudKey,
        const std::vector<ubyte>& rgbByteColorArr
    ) = 0;

### pushParticleTrace

    virtual ExpectedKey pushParticleTrace(
        const std::vector<float>& positionArr,
        const std::vector<float>& timeStampArr,
        std::string tag = "",
        const OptionalParticleTraceData& optionalParticleTraceData = OptionalParticleTraceData()
    ) = 0;

### pushParticleTraceSettings

    virtual ExpectedKey pushParticleTraceSettings(
        const ParticleTraceSettings& settings
    ) = 0;

### addParticleTraceGroup

    virtual ExpectedKey addParticleTraceGroup(
        const std::vector<ResourceKey>& particleTraceKeyArr,
        ResourceKey particleTraceSettingsKey
    ) = 0;

### deleteStream

    virtual Status deleteStream(
        std::string streamName
    ) = 0;

### deleteFrames

    virtual Status deleteFrames(
        std::string streamName,
        const std::vector<ResourceKey>& frameKeyArr
    ) = 0;

### Other Items Still Todo

> - Streaming of initial low-res geometry
> - The parentMeshKey concept is still not implemented

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