Asynchronous simulation loop

[alxbilger]

Rendering and simulation loops run asynchronously. This allows different update frequencies. The rendering loop enables VSync, such that it runs at the frequency of the monitor (in my case 60 Hz), while the simulation loops runs as fast as possible.

The rendering and GUI is always responsive, even for slow simulations, running much slower than the rendering frequency. On the opposite, if the simulation is much faster, the rendering loop always runs at the frequency of the monitor, limiting the accesses to GPU resources.

Until now, the rendering and simulation loops were run sequentially. With the asynchronicity, the accesses to the scene graph and SOFA data structures becomes thread-unsafe. To allow to keep rendering a mesh responsively, the scene to be rendered is captured at every simulation tick. The rendering loop always renders the latest snapshot.

To do:

• Capture the camera properties to remove all the camera accesses in the rendering loop
• Investigate VisualParams thread-safety
• Implement a command queue for the GUI
• Capture all the displayed Data in the GUI
• Deal with Visual models
• Deal with OglSceneFrame
• Capture DrawTool features (lighting, blending etc)
• Show the physics frequency in imgui
• Deal with the video recorder
• Indication that the simulation is running after a given timeout

Example where the sim runs faster than the rendering:

simu_faster.mp4

Example where the rendering is faster than the sim:

sim_slower.webm