This adds math classes for doing frustum culling in software. These could be used for optimizing performance in many other places as well. For example, if an actor is outside the view frustum, it may not be necessary to do expensive keyframe animation and vertex skinning calculations for that actor.
Lighting is done by calculating vertex colors in software, since the attenuation model used in EMI cannot be simulated with OpenGL fixed function lighting. The original game does the lighting this way as well. Ideally for the modern shader-based renderer a shader would be used for this instead.
In GRIM the position, direction and the roll of the camera is set via
gluLookAt but in EMI the camera is steady and its view is adjusted via
matrix rotations.
This patch adjusts the calculation for EMI and refactors the code to
do the calculation in the separate function Set::calculateSoundPosition.
That function will be used for implementing the positional sounds in
EMI.
Previously, we split the background layers into everything
before SO 15 and after, and drew like that. However, this caused
the pink ship in shi.setb to not be drawn.
This patch draws the layers of the background at intervals of ten.
So if a set has six layers, layer 5 is the background and 4,3,2,1,0
are rendered at sortorder 40,30,20,10,0.
