Slow rendering of small 7000 atom atomic model, 2bbv

[Tom Goddard]

Rendering 2bbv with full lighting is surprisingly slow (11 frames per second, MacBook Pro 2012, Nvidia GT650M graphics) given that it is only 7000 atoms shown as spheres.

The problem is that it is rendering 8 million triangles, more than 1000 per atom sphere because the level-of-detail code sets the detail to remain under 10 million triangles with max of 2000 triangles per atom. This is suitable for modern higher performance graphics, but not this old laptop graphics. The current level-of-detail code takes not account of the performance of the processor.

Need to improve the level-of-detail to get good balance of quality and speed on graphics with different performance levels.

[Tom Goddard]

Although code could monitor the graphics performance and adapt to the measured rendering times, this is likely to give unpredictable and unreproducible rendering quality.

A better approach for this specific case would be to switch to impostor sphere rendering which requires no level-of-detail control, always giving pixel-level quality. Handling perspective projection complicates this approach.