- \n
- OpenGL<\/em> compatibility profile<\/a><\/li>\n
- OpenGL<\/em> core profile<\/a><\/li>\n
- SoGLCallback<\/a><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
Appendices<\/p>\n
- \n
- Appendix A: A Open Inventor state against OpenGL<\/em> state<\/a><\/li>\n
- Appendix B: OpenGL compatibility custom node source code example<\/a><\/li>\n
- Appendix C: OpenGL core custom node source code example<\/a><\/li>\n
- Appendix D: SoGLCallback source code example<\/a><\/li>\n<\/ul>\n
\nIntroduction<\/h3>\n
<\/a>Open Inventor render engine
\n<\/strong>Starting with Open Inventor 10, all graphics API calls are executed by a render engine, a software layer between hardware and\u00a0Open Inventor public API (see Figure 1.1<\/a>). This\u00a0render engine has changed the product design, as\u00a0the Open Inventor public API is now independent of any graphics API. This paradigm has many advantages, including, maintenance, optimizations and future graphics API support. On the other hand, new concepts introduced in Open Inventor 10 involve changes in user code, especially for custom nodes which require strict guidelines comparing to\u00a0previous versions.<\/p>\n<\/a><\/p>\n
![\"\"](\"https:\/\/developer.openinventor.com\/wp-content\/uploads\/2023\/12\/architecture2.png\")
<\/p>\n<\/p>\n
Figure 1.1:<\/strong> Open Inventor simplifed architecture. Open Inventor public API is the higher layer which represents the user API. The render engine is the intermediate layer between Open Inventor and graphics API which contains a specialized backend layer for communication with graphics API, here the OpenGL API.<\/p>\n
As shown in Figure 1.2<\/a>, during a\u00a0SoGLRenderAction<\/a><\/em><\/strong>, the scene graph traversal generates\u00a0a set of render engine commands<\/em> which represent a description of the scene (materials, shapes, and so on). Note that during the scene graph traversal, there is no call to any low-level graphics API. In the same way, render engine commands have no dependencies on\u00a0the scene graph API. When the scene graph traversal is finished, the generated commands are executed by the render engine, which makes the necessary low-level rendering calls.<\/p>\n
<\/a><\/p>\n
![\"\"](\"https:\/\/developer.openinventor.com\/wp-content\/uploads\/2023\/12\/renderengine2.png\")
<\/p>\n<\/p>\n
Figure 1.2: SoGLRenderAction<\/a><\/strong><\/em><\/strong> flow chart. First, the function apply is called on a scene graph which leads to a scene graph traversal. During the traversal, a set of commands is setup that represents an abstraction of the rendering execution for the render engine. Finally, commands are submitted to the render engine in order to be transformed into rendering calls.<\/p>\n
\n<\/a>Custom Nodes
\n<\/strong>Introduced with Open Inventor 10, each node contains a SbRenderEngineMode<\/a><\/strong><\/em> static class member which defines how a node is executed by the Open Inventor render engine. The render mode, of type SoNode<\/a><\/strong><\/em>::RenderMode, should be defined with one of the following values:<\/p>\n- \n
- \n
- \n
- \n
- \n
- OIV_OPENINVENTOR_RENDERING<\/strong>, for custom nodes that use only Open Inventor API (see Section 2).<\/li>\n
- OIV_OPENGL_COMPATIBILITY_RENDERING<\/strong>, for custom nodes that work in OpenGL compatibility profile.<\/li>\n
- OIV_OPENGL_CORE_RENDERING<\/strong>, for custom nodes that work in OpenGL core profile.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
Please refer to Chapters Pure Open Inventor custom nodes<\/a> and OpenGL<\/em> custom nodes<\/a> for details of what the choice of a render mode involves.<\/p>\n
\u00a0 \u00a0 \u00a0 \u00a0 Accessible via the getClassRenderEngineMode<\/strong> static function, the render mode must be initialized during the static class initialization (i.e., initClass<\/strong> function) such as shown in Listing 1.1. <\/strong><\/p>\n
- OIV_OPENGL_COMPATIBILITY_RENDERING<\/strong>, for custom nodes that work in OpenGL compatibility profile.<\/li>\n
- OIV_OPENINVENTOR_RENDERING<\/strong>, for custom nodes that use only Open Inventor API (see Section 2).<\/li>\n
- \n
- Appendix B: OpenGL compatibility custom node source code example<\/a><\/li>\n
- OpenGL<\/em> core profile<\/a><\/li>\n