Package com.openinventor.inventor.nodes

Class SoBufferedShape

java.lang.Object
com.openinventor.inventor.Inventor
com.openinventor.inventor.misc.SoBase
com.openinventor.inventor.fields.SoFieldContainer
com.openinventor.inventor.nodes.SoNode
com.openinventor.inventor.nodes.SoShape
com.openinventor.inventor.nodes.SoBufferedShape
All Implemented Interfaces:
SafeDisposable
Direct Known Subclasses:
SoVolumeBufferedShape
public class SoBufferedShape extends SoShape
Node to render geometry stored in SoBufferObject objects. SoBufferedShape is useful to manage the rendering of large geometry, provide application control over where the data is stored (CPU or GPU) and to integrate rendering with the Open Inventor computing framework (through the SoBufferObject classes).

SoBufferedShape provides fields for:

  • Vertices
  • Indices (optional)
  • Colors (optional)
  • Normals (optional)
  • Texture coordinates (optional)

In this sense it is similar to the SoVertexProperty node, but SoVertexProperty is just a property node. SoBufferedShape also does the rendering of the shape. Properties that are not specified are taken from the traversal state (e.g. colors) or computed (e.g. normals).

SoBufferedShape can render many types of geometric primitives including points, lines, quads and triangles. (A single type must be specified per instance of SoBufferedShape.) You specify the type of primitive in the SoSFEnum field shapeType.

SoBufferedShape can render multiple primitives of the same type. You can specify the number of vertices (or indices if provided) to use for each primitive in the SoMFInt32 field numVertices (similar to SoFaceSet).

You can also use the primitive restart feature to define multiple indexed strip shapes, for example TRIANGLE_STRIP or LINE_STRIP. The end of each primitive is marked by a special index value in the index buffer and this value can be specified in the primitiveRestartValue field. The behavior is similar to the "-1" value that can be used in Open Inventor indexed shape nodes like SoIndexedFaceSet, but is implemented on the GPU.
NOTE:

The geometry and its attributes must be stored in buffer objects (see SoBufferObject). The buffer objects can be SoGpuBufferObjects stored directly on the graphics board or SoCpuBufferObjects stored in system memory. This allows the application to control what data is stored where.

In the general case, when the underlying buffer object is modified using the SoBufferObject API (setSize, map, memcpy, memset), the containing SoSFBufferObject field needs to be notified using touch() in order for Open Inventor to take this modification into account. If touch() is not called, there is no guarantee that the modifications will be visible on the next rendering.

If the application needs to frequently modify the values of an SoBufferObject, calling touch() on the field can result in an undesirable decrease in performance. Instead, it is recommended to use an instance of SoGpuBufferObject and set the shapeUsage field to DYNAMIC. These settings guarantee that this buffer data will be used directly for rendering, and eliminate the need to call touch() on the field. It also guarantees that modifications to the buffer done by shaders will be properly taken into account.

If lighting is enabled (there is no SoLightModel node or the model field of the SoLightModel is set to PHONG) and the normalBuffer field is not set, then Open Inventor will automatically compute normal vectors, but only in some cases (see Limitations section). Normal generation is affected by the creaseAngle field of the SoShapeHints node, but only if the vertices are NOT indexed (indexBuffer field is not set). If the vertices are indexed the creaseAngle is forced to PI, creating a smooth surface rendering. If the application needs to render sharp edges on a shape, either compute normal vectors and set the normalBuffer field or do not use the indexBuffer field. It is possible to disable normal generation (if for example the normals are generated by a geometry shader) by setting the useNormalsGenerator field to false. If no normal vectors are specified or generated, and lighting is enabled, the primitive may not be rendered correctly.

SoBufferedShape provides fields to describe the content of each buffer, e.g. the data type and number of components in each buffer, as well as how to access the buffers, e.g. the offset into the buffer and "stride" separating data values in the buffer. The default values for offset and stride assume that the vertices, normals, etc are each in a separate buffer. However setting appropriate offset and stride allows, for example, vertices and normals to be interleaved in a single buffer. In this case the same buffer would be set into both the vertexBuffer and normalBuffer fields.

To disable computing the bounding box, which can take a long time with very large geometry, use the SoBBox node to specify a pre-computed bounding box.

# Limitations

  • Transparency: If there is no color buffer, making the entire shape transparent using an SoMaterial or an SoPhysicalMaterial node works as usual. However if there is a color buffer with RGBA values, note that Open Inventor does not currently check the color buffer for transparency (alpha values < 1). So in this case the SoBufferedShape will not be considered transparent geometry (even if there are alpha values < 1) and may not be rendered correctly. You can force Open Inventor to handle the shape as transparent geometry by putting a transparent base color before this shape in the scene graph.
  • Normal generation: If lighting is enabled and the normalBuffer field is not set, then Open Inventor will automatically compute normal vectors, but only in some cases. Automatic generation of normal vectors is ONLY enabled when:
    • The vertexComponentsCount field is set to 2 or 3,
    • The primitiveRestartEnabled field is set to false (default), and
    • The primitives are TRIANGLES, TRIANGLE_STRIP or QUADS.
      Note: The crease angle (see SoShapeHints) is not used by the normal generator if the vertices are indexed. If the application needs to render sharp edges on a shape, either compute normal vectors and set the normalBuffer field or do not use the indexBuffer field.
  • SoGetPrimitiveCountAction: When using the primitive restart feature, the triangle/line count returned by the SoGetPrimitiveCountAction will not be accurate.
  • Concave polygons: Unlike (for example) SoFaceSet, SoBufferedShape does NOT automatically tesselate concave or complex polygons. Such primitives may not be rendered correctly.
  • SoWriteAction: SoBufferedShape can be saved to and restored from a .iv file just like any other Open Inventor node. However, during the read operation any GPU buffer objects (SoGpuBufferObject) in the file will be created as CPU buffers (SoCpuBufferObject).
  • Material binding (etc): SoBufferedShape effectively only supports per-vertex and per-vertex-indexed binding of materials, normals and texture coordinates using the values found in its own buffers.
  • Double-sided coloring: When multiple static buffered shapes (see shapeUsage) share the same buffers, you cannot use a single color buffer for both the front and back faces because SoBufferedShape does not support interlacing colors. Therefore, you must use two separate color buffers.

Example using CPU buffer: 

 // Result should be similar to SoLineSet example in PG-GettingStarted.pdf.
 // This example does not show any of the advantages of using SoBufferedShape,
 // just the simplest possible setup and usage.
 // Coordinate data
   float[] vertices = {
           1.0f, 0.5f,0.0f, 0.0f, 1.0f,0.0f, -1.0f,0.5f,0.0f,
          -1.0f,-1.0f,0.0f, 1.0f,-1.0f,0.0f,  1.0f,0.0f,0.0f, -1.0f,0.0f,0.0f,
          -1.0f,-1.5f,0.0f, 1.0f,-1.5f,0.0f
   };
   int[] numVerts = { 3, 4, 2 };
 
 // Create a CPU buffer object and set its size (allocate memory)
 SoCpuBufferObject cpuBuffer = new SoCpuBufferObject();
 cpuBuffer.setSize( vertices.length Float.SIZE/8 );
 
 // Copy vertex data into the buffer object
 FloatBuffer vertData = cpuBuffer.map( SoBufferObject.AccessModes.SET ).asFloatBuffer();
     vertData.put(vertices);
 cpuBuffer.unmap();
 
 // Create a buffered shape to render the geometry
 SoBufferedShape shape = new SoBufferedShape();
 shape.shapeType.setValue( "LINE_STRIP" );
 shape.numVertices.setValues( 0, numVerts );
 shape.vertexBuffer.setValue( cpuBuffer );

Example using GPU buffer: 

 // Result should be similar to SoLineSet example in PG-GettingStarted.pdf.
 // This example does not show any of the advantages of using SoBufferedShape,
 // just the simplest possible setup and usage.
 // Coordinate data
   float[] vertices = {
           1.0f, 0.5f,0.0f, 0.0f, 1.0f,0.0f, -1.0f,0.5f,0.0f,
          -1.0f,-1.0f,0.0f, 1.0f,-1.0f,0.0f,  1.0f,0.0f,0.0f, -1.0f,0.0f,0.0f,
          -1.0f,-1.5f,0.0f, 1.0f,-1.5f,0.0f
   };
   int[] numVerts = { 3, 4, 2 };
 
 // Create a GPU (OpenGL) buffer and set its size (allocate memory)
 SoGLContext glContext = new SoGLContext( true );
 glContext.bind();
     SoGpuBufferObject gpuBuffer = new SoGpuBufferObject( SoGpuBufferObject.BufferAccessFrequencies.STATIC, SoGpuBufferObject.BufferAccessNatures.SHARED );
     gpuBuffer.setSize( vertices.length Float.SIZE/8 );
 
 // Copy vertex data into the GPU buffer object
 FloatBuffer vertData = gpuBuffer.map( SoBufferObject.AccessModes.SET ).asFloatBuffer();
     vertData.put(vertices);
 gpuBuffer.unmap();
 
 glContext.unbind();
 
 // Create a buffered shape to render the geometry
 SoBufferedShape shape = new SoBufferedShape();
 shape.shapeType.setValue( "LINE_STRIP" );
 shape.numVertices.setValues( 0, numVerts );
 shape.vertexBuffer.setValue( gpuBuffer );

LIMITATIONS: SoBufferedShape needs a graphic card supporting vertex buffer objects, if not available shape won't be rendered.

File format/default:

BufferedShape {

    useNormalsGenerator true
    shapeType TRIANGLES
    numVertices 0
    vertexBuffer NULL
    vertexComponentsCount 3
    vertexComponentsType SbDataType.FLOAT
    vertexStride 0
    vertexOffset 0
    normalBuffer NULL
    normalComponentsType SbDataType.FLOAT
    normalStride 3 sizeof(float)
    normalOffset 0
    indexBuffer NULL
    indexType SbDataType.UNSIGNED_INT32
    indexOffset 0
    colorBuffer NULL
    colorComponentsType SbDataType.FLOAT
    colorStride 0
    colorOffset 0
    colorComponentsCount 3
    texCoordsBuffer NULL
    texCoordsComponentsType SbDataType.FLOAT
    texCoordsStride 0
    texCoordsOffset 0
    texCoordsComponentsCount 2
    primitiveRestartEnabled false
    primitiveRestartValue -1
}

Action behavior:

SoGLRenderAction, SoCallbackAction, SoBoundingBoxAction Do the actual rendering / bounding box computation.

See Also:

  • Field Details

    • shapeUsage

      public final SoSFEnum<SoBufferedShape.Usages> shapeUsage
      Defines the usage of the shape. Some optimizations can be performed when we know the usage of the shape. Most of the time if the buffer objects attached to the shape are updated on a regular basis prefer using DYNAMIC, otherwise prefer STATIC.

      STATIC provides the best performance when the content of the buffer is never modified or modified infrequently.

      . The default value is STATIC.

      Since:
      Open Inventor 9.2

    • primitiveRestartEnabled

      public final SoSFBool primitiveRestartEnabled
      Enable/disable the primitive restart feature. Default is false. Primitive restart allows you to define multiple indexed strip shapes using only one index buffer. Each time the primitive restart index is reached a new strip or loop of primitives is emitted. This feature is similar to the "-1" that can be used in the OIV indexed shapes This also means that the availability must be checked before being used

      Limitations: Enabling primitive restart disables the normal generator.

      Since:
      Open Inventor 8.5

    • primitiveRestartValue

      public final SoSFInt32 primitiveRestartValue
      Index value for the primitive restart feature. Default is -1.

      Since:
      Open Inventor 8.5

    • useNormalsGenerator

      public final SoSFBool useNormalsGenerator
      Indicates if the node should use the internal normal vector generator if no normals are defined. Default is true.

      This mode is only supported for shapes with float coordinates and 3 components per vertex. It is not supported for the points and the lines.

      Disabling the normal generator can be useful if the normals are computed in a shader or if the shaders don't need any normal at all.

      Normal generation is affected by the creaseAngle field of SoShapeHints.

    • shapeType

      public final SoSFEnum<SoBufferedShape.Types> shapeType
      Shape type to render. . Default is TRIANGLES.

    • numVertices

      public final SoMFInt32 numVertices
      Total number of vertices/indices or number of vertices/indices to be used per primitive. Specifically:
      • For the shape types POINTS, LINES, TRIANGLES and QUADS
        Only the first value is meaningful and it specifies the number of vertices to be used for rendering. Specifically:
        • For a list of points: numVertices should be the number of points to be drawn.
        • For a list of lines: numVertices should be num_lines * 2 where num_lines is the number of lines to be drawn.
        • For a list of quadrangles: numVertices should be num_quads * 4 where num_quads is the number of quadrangles to be drawn.
        • For a list of triangles: numVertices should be num_tri * 3 where num_tri is the number of triangles to be drawn.
      • For all other types:
        The number of values in this field specifies the number of primitives that will be drawn.
        Each value in the field specifies the number of vertices (or indices if given) to be used for each primitive.

    • vertexBuffer

      public final SoSFBufferObject vertexBuffer
      Buffer object that contains the vertex data.
      Default is no buffer. Note: This buffer must be an SoCpuBufferObject or SoGpuBufferObject. (SoGLBufferObject with target = ARRAY_BUFFER is also allowed but not recommended.)

    • vertexComponentsCount

      public final SoSFShort vertexComponentsCount
      Number of components in each vertex. Default is 3 (i.e. X, Y and Z).

    • vertexComponentsType

      public final SoSFEnum<SbDataType.DataTypes> vertexComponentsType
      SbDataType.DataType for vertices. . Default is SbDataType.FLOAT.

    • vertexStride

      public final SoSFShort vertexStride
      Stride in bytes between the first component of two consecutive vertices.
      Default is 0. e.g: If the vertices are composed of 3 float components the stride should be 3 * sizeof(float). If RGB colors are packed in the same buffer the stride should be 3 * sizeof(float) + 3 * sizeof(float), the second part stands for the extra data padding.

      Note: When the values are packed (only vertices in the buffer) the value 0 can be used and OpenGL will compute the stride value.

    • vertexOffset

      public final SoSFInt32 vertexOffset
      Offset in bytes to the first vertex within the buffer. Default is 0.

    • normalBuffer

      public final SoSFBufferObject normalBuffer
      Buffer object that contains the (optional) normal vectors.
      Default is no buffer. Note: This buffer must be an SoCpuBufferObject or SoGpuBufferObject. (SoGLBufferObject with target = ARRAY_BUFFER is also allowed but not recommended.)

    • normalComponentsType

      public final SoSFEnum<SbDataType.DataTypes> normalComponentsType
      SbDataType.DataType type for the normal vectors. . Default is SbDataType.FLOAT.

    • normalStride

      public final SoSFShort normalStride
      Stride in bytes between the first component of two consecutive normals. Default is 0. e.g: If the normals are composed of 3 float components the stride should be 3 * sizeof(float). If RGB colors are packed in the same buffer the stride should be 3 * sizeof(float) + 3 * sizeof(float), the second part stands for the extra data padding.

      Note: When the values are packed (only normals in the buffer) the value 0 can be used and OpenGL will compute the stride value.

    • normalOffset

      public final SoSFInt32 normalOffset
      Offset in bytes to the first normal vector in the buffer. Default is 0.

    • indexBuffer

      public final SoSFBufferObject indexBuffer
      Buffer object that contains the (optional) indices. Default is no buffer. Note: This buffer must be an SoCpuBufferObject or SoGpuBufferObject. (SoGLBufferObject with target = ARRAY_BUFFER is also allowed but not recommended.)

    • indexType

      public final SoSFEnum<SbDataType.DataTypes> indexType
      SbDataType.DataType type for the indices. . Default is SbDataType.UNSIGNED_INT32. Note: Due to OpenGL restrictions, only 3 values are accepted here: SbDataType.UNSIGNED_INT32, SbDataType.UNSIGNED_BYTE or SbDataType.UNSIGNED_SHORT.

    • indexOffset

      public final SoSFInt32 indexOffset
      Offset in bytes to the first index in the buffer. Default is 0.

    • colorBuffer

      public final SoSFBufferObject colorBuffer
      Buffer object that contains the (optional) color values. Default is no buffer. Colors are always per-vertex or per-vertex-indexed. Note: This buffer must be an SoCpuBufferObject or SoGpuBufferObject. (SoGLBufferObject with target = ARRAY_BUFFER is also allowed but not recommended.)

    • colorComponentsType

      public final SoSFEnum<SbDataType.DataTypes> colorComponentsType
      SbDataType.DataType type for the color values. . Default is SbDataType.FLOAT.

    • colorStride

      public final SoSFInt32 colorStride
      Stride in bytes between the first component of two consecutive colors.
      Default is 0. e.g: If the colors are composed of 3 float components the stride should be 3 * sizeof(float). If vertices are packed in the same buffer the stride should be 3 * sizeof(float) + 3 * sizeof(float), the second part stands for the extra data padding.

      Note: When the values are packed (only color values in the buffer) the value 0 can be used and OpenGL will compute the stride value.

    • colorOffset

      public final SoSFInt32 colorOffset
      Offset in bytes to the first color value in the buffer. Default is 0.

    • colorComponentsCount

      public final SoSFInt32 colorComponentsCount
      Number of components in each color value. Default is 3 (i.e. red, green and blue)

    • texCoordsBuffer

      public final SoMFBufferObject texCoordsBuffer
      Buffer objects that contains the (optional) texture coordinates.
      Default is no buffer. Note: This buffer must be an SoCpuBufferObject or SoGpuBufferObject. (SoGLBufferObject with target = ARRAY_BUFFER is also allowed but not recommended.)

    • texCoordsComponentsType

      public final SoMFEnum<SbDataType.DataTypes> texCoordsComponentsType
      SbDataType.DataType type for the texture coordinates. . Default is SbDataType.FLOAT.

    • texCoordsStride

      public final SoMFInt32 texCoordsStride
      Stride in bytes between the first component of two consecutive texture coordinates.
      Default is 0. e.g: If each element is composed of 2 float components the stride should be 2 * sizeof(float). If vertices are packed in the same buffer the stride should be 2 * sizeof(float) + 3 * sizeof(float), the second part stands for the extra data padding.

      Note: When the values are packed (only texture coordinates in the buffer) the value 0 can be used and OpenGL will compute the stride value.

    • texCoordsOffset

      public final SoMFInt32 texCoordsOffset
      Offset in bytes to the first texture coordinate in the buffer. Default is 0.

    • texCoordsComponentsCount

      public final SoMFInt32 texCoordsComponentsCount
      Number of components in each texture coordinate. Default is 2 (i.e. S and T)

  • Constructor Details

    • SoBufferedShape

      public SoBufferedShape()
      Default constructor.