Sorting and the cache

A radar answers not «who is there» but «who is best». And it does not answer afresh every time

mediumYou need: Finding a unit

steptick 0

Radar0

target1enemytarget2anytarget3anysortdistanceradarsortOrderoutput

Radar1

target1enemytarget2anytarget3anysortdistanceradarsortOrderoutput

Radar2

target1enemytarget2anytarget3anysorthealthradarsortOrderoutput

Radar3

target1enemytarget2anytarget3anysorthealthradarsortOrderoutput

Sensor4

=

 in

Sensor5

=

 in

Stop6

@counter0number

nearnullnull

farnullnull

toughnullnull

weakestnullnull

nearHealthnullnull

weakHealthnullnull

Four radars, all with the same filters — only the measure and the order differ. The dagger is closer and healthier, the flare further away and weaker.

What to measure by

Measure	What it compares
distance	the distance to the block
health	current health
maxHealth	maximum health
shield	shield
armor	armour

The order: the sixth field

Zero and one flip the choice:

Measure and order	Who it finds
distance 1	the nearest
distance 0	the furthest
health 1	the toughest
health 0	the weakest

An easier way to remember it: one means “the best by the measure”, zero “the worst”. For distance, “best” means nearest, because that is usually who you are after.

Note

Finishing enemies off works well with health 0: a wounded one dies sooner, and the turret does not spread its ammo over the healthy. “The most dangerous”, though, cannot be expressed by one measure — that needs filters and a check of your own afterwards.

The answer refreshes once every 30 ticks

steptick 0

Radar0

target1enemytarget2anytarget3anysortdistanceradarsortOrderoutput

Control1

set shoot predict of

unitshoot

Sensor2

=

 in

Operation3

=

+

@counter0number

aimnullnull

deadnullnull

loopsnullnull

A radar does not search afresh every iteration. A block’s result is recomputed once every 30 ticks — half a second — and between recomputations the previous answer is handed back. This is done for speed: a dozen radars in a program would otherwise eat a frame.

Press “run” and watch dead. The turret finishes the flare off, and for a while aim still points at it — only now with @dead equal to one.

Silent failure

A target from a radar may already be dead. Up to half a second passes between the death and the recomputation, and all that time the program is commanding a corpse: control shootp will aim the turret at a body, and ucontrol will lead a unit to a place where nobody is.

So what was found is checked before it is used:

radar enemy any any distance duo1 1 aim
sensor dead aim @dead
jump 6 notEqual dead 0

Note

The cache belongs to the line of the program, not to the block: two radars on different lines are counted separately even if they ask the same thing. So identical radars are worth writing once and putting the result into a variable.

Remember

• There are five measures; the sixth field flips the choice.
• distance 1 is the nearest, health 0 the weakest.
• The answer is recomputed once every 30 ticks; in between, the previous one is given.
• The unit found may already be dead: check @dead.

Task

Change the measure health in the first example to maxHealth and run it: tough stays the dagger — its maximum health is higher too. But wound the dagger and health and maxHealth start answering differently.

Then give all four radars the order 1 and compare near with far: they become the same unit.