Code Optimisation

Written it twice? Put it in a function

Pre-compilation by the game engine can save up 20x the amount of time processing, even if the initial time is slightly lengthened. If you've written it twice, or if there is a kind of loop consistently being compiled (perhaps a script run by execVM), make it into a function (FUNCVAR =compile preprocessfilelinenumbers "filename.sqf").

Adding elements to an array

• set is 56x faster than binary addition (_a set [count _a,_v] vs _a = _a + [_v])

Getting position

• getPosASL/getPosATL are 1.67x FASTER than regular getPos

Loops

These first two loop types are identical in speed (+/- 10%), and are more than 2x as fast the proceeding two loop types.

• for "_y" from 0 to (count [0,0,0,0] - 1) step 1 do { ... };
• { ... } foreach [0,0,0,0];

Where as these two loops are much slower, and for maximum performance, avoided.

• _y=0; while {_y = _y + 1; _y < count [0,0,0,0]} do { ... };
• for [{_y=0},{_y<(count [0,0,0,0])},{_y=_y+1}] do { ... }

Avoid O(n^2)!!

Commonly you may set up foreach foreach's. 'For' example:

• { { ... } foreach [0,0,0]; } foreach [0,0,0];

This example is of the order (n^2) (3^2 = 9 iterations). For each element you add to this, it will increase the processing exponentially. Which can lead to poor performance in snap functions.

Avoiding the 0.3ms delay

Many times you may want to avoid the 0.3 ms delay (not 3ms!), and there a few tricks around how to do it...

• Triggers are inside what we call the 'non-scheduled' environment.
• All pre-init code executions are without scheduling.
• FSM conditions are without scheduling

Measuring Velocity Scalar

Sure we can just use Pythagorean theorem to calculate the magnitude from a velocity vector, but a command native to the engine runs much faster (over 10x faster) than the math.

• VECTOR distance [0,0,0]

Works for 2D vectors as well.