TODO

TODO list for unforseen future:

Hard and medium changes:
1. Introduce a new tree node type which holds holes in space instead of solid voxels. (In progress,
   see voxtrees-ng branch).
   1.1 Rewrite insertion/deletion and search algorithms.
2. Level of details. Maybe do not render those voxels which are only a few pixels in width.
   2.1 Or another idea: drop some rays (say 1 of 2) if they travel a long way from origin. (DONE: 23 jan 2018)
3. Render image with 4x4 squares. Exploit "locality" in each square. (DONE: September 2017)
   3.1 Do something with possible quality degradation. (DONE: 08 Jan 2018, but some improvements can
   be made to adaptive mode).
4. Add some FPS games experience.
   4.1 Write a new camera with 5 degrees of freedom (with one rotation axis "locked"). (DONE: 22 oct 2017)
   4.2 Maybe write utility functions for fast replacement of camera methods. (DONE: 05 sep 2017).
       Maybe write a dummy camera. (DONE: 21 oct 2017)
   4.3 Add gravity to collision detector.
5. Maybe store the camera's basis in its structure. Rotate using this basis (for much more fast rotation).
   (Not needed now).
6. Replace counters with Dtrace probes in statistics. (DONE: 06 sep 2017)
7. Investigate a huge slowdown in example1.lua after the commit: 69406f4fb (Remove lua vox_dot and vox_box types...)
   (DONE: 12 sep 2017)
8. Investigate camera axes inversion after call to look_at method in simple camera. (DONE: 25 oct 2017)
9. Merge lights branch without much degradation in speed. (DONE: 27 jan 2018). Add some procedural generated textures.
10. Remove legacy non-SSE code and make type vox_dot equal to __v4sf.

Easy changes:
1. Allow dynamic modification of the voxel tree in lua engine (just like as in demo application)
   (DONE: late 2017).
2. Screen geometry must not bring destortion in rendered scene. (DONE: 04 sep 2017)
3. Use queue in statistic histograms. (DONE: 04 sep 2017)
4. Improve deletion from M-trees (reparent a node if its parents has this node as its only child). (DONE: 02 feb 2018).