The SoBufferedShape node uses SoBufferObject which contains the actual data of the geometry. In this demo the vertices buffer contains fake data and the actual data is computed by the geometry shader on the fly. OpenGL requires a valid vertices buffer even if it is not used.
The SoBBox node is used to provide a bounding box because as long as there is no data OIV cannot compute the bounding box.
Only the shaders parameters are sent to modify the geometry using the DialogViz API.
SoBufferedShape, SoBBox, SoGLBufferObject, SoShaderProgram, SoVertexShader, SoFragmentShader, SoGeometryShader