class Tringula: public ZNode, public TimeMakerClient

 Override settings from ZGlass

 Intersect terrain mesh with given ray and stores result in col_faces.
  ray_length - if larger then 0, used as maximum hit distance.
  cull_p     - enable / disable triangle culling.
  closest_p  - return closest hit only / all hits.

 Returns distance to the closest terrain hit from given ray.
 Opcode::MAX_FLOAT is returned if terrain is is not hit.

 Select picking candiadates from among extendios.

 Loop over extendios and calculate distance between ray and center
 point.
  ray_length   - if larger than 0, limits the maximum extendio distance.
  ext_distance - if non 0, set to the distance of extendio.

 Original idea was to sub-divide ray into boxes and do split box prunning.

 Could increase size of boxes further away.

 In fact, only need to calculate until the first contact with terrain.

 Check both options.

 Returns height to which the trans was placed.

 Randomly select a mesh for statico from mesh_list and place it on
 a random location on the terrain. Makes sure the new statico
 does not overlap with existing ones.

 check_inside: make sure all corners of the bbox are within
   parasurf which is relevant for planar surfaces where statos might
   stick out.
   check_inside is also passed to place_on_terrain() where it
   suppresses the warnings about missed intersection.
 max_tries: how many times to try statico's placement on terrain.
   If this limit is reached an exception is thrown.
   As CINT doesn't handle this very well, 0 is returned at the moment.

   This is relevant when many staticos are already on the terrain
   and for steep terrain.

 How much of statico's bbox must stick out of terrain on each
 sampling-point is hardcoded to 0.5*bbox_z_size.

 Checks if dyno crossed some important boundary and handles that.
 This means that Dyno's velocity and transformation matrix might be
 modified.

 Distance to the closest boundary is returned in safety argument.

 Returns true if transformation matrix of the dynos gets changed.

 In future, when an inter-tringula boundary is crossed this will
 also pass the dyno to neighbouring tringula.

 Du full box-prunning step:
 - fill prunning list with statos, dynos and flyers,
 - perform box prunning,
 - do detail checks on collision candidates.

 Output: mItsLines contain intersection segments from all collisions.

 Mainly here to compare speed against split-box-prunning.

 Extendio-extendio collision detection and handling routine.

 Preliminary, should be done in a more general way with other weapons.
 Also, need spot surface and ray divergence. Or sth.

 Make sure internal representation of static and dynamic objects
 for box-pruning is ok.

 Calculates height of given point and of the terrain at given pos.
 Return true if all went ok.

 Place statico on terrain so that the bounding box of the mesh
 touches or penetrates the terrain. The distance is sampled on a
 3x3 grid.

 It is assumed that the statico is oriented along the local up
 direction with zero height. If the trans matrix were fixed here,
 the rotation would be somewhat poorly defined.

 check_inside - if true, the first miss of the terrain in the ray
 collision test results in a termination of the loop over sampling
 points. false is returned and no error message is printed.

 min_h_above - how much of statico's bbox must stick out of
 terrain on each sampling-point. If this is not the case, false is
 returned. If min_h_above <= 0, the check is not performed.

 Otherwise true is returned.

 If lens is not dying, send a MIR requesting its deletion.