Doom Engine source code review
Summary
In 1993, only the very high-end 486DX machines had a FPU (floating point unit) hence Doom engine was doing all angles calculation via Binary Angular Measurement (BAMs), relying on only, is rarely used. If two subSectors shared the same material (height, texture and illumination level) Doom engine tried to merge them together but because of the structure limitation it was not always possible. Here are the starting screens three main visplanes: The green one is particularly interesting as it illustrates ability to store discontinued areas (but only horizontally). Those are rendered far to near but are not projected into screen space using the walls lookup table, its all done with 16.16 binary fixed point calculations. • Since Doom was developed on a NeXTSTEP system using a flat virtual memory model, id Software decided against using EMS or XMS like most games of the time.