Differential D2086

Fix ranges when treating a target as a circle
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Authored by wraitii on Jul 16 2019, 8:44 PM.

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rP22495: Fix max-range approach when treating a target as a circle.

Trac Tickets

#5512

Summary

As reported by @bb in #5512, catapults and other big-range units might not approach targets correctly when trying to get in range.

The problem is that we can't ask the pathfinder to go in range of a rounded rectangle.
So we approximate the target as a circle. But we pick the circumscribing circle. In cases where we don't approach the corner, the distance "circumscribing-circle" to entity will be higher than the real "square-obstruction" to entity distance, and we won't get in range.

To fix this, we need to get in range of the inscribed circle.

Test Plan

This fixes the replay at #5512.
Review that it makes sense mathematically.

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rP 0 A.D. Public Repository

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Build Status

Buildable 8399
Build 13721: Vulcan Build	Jenkins
Build 13720: arc lint + arc unit

Event Timeline

wraitii created this revision.Jul 16 2019, 8:44 PM

Successful build - Chance fights ever on the side of the prudent.

Link to build: https://jenkins.wildfiregames.com/job/docker-differential/100/display/redirect

Harbormaster completed remote builds in B8399: Diff 8935.Jul 16 2019, 8:49 PM

Didn't test it, but what happens now if minRange =~ maxRange, then it could be that the circumscribed circle for the minRange is bigger than the inscribed circle for maxRange...

In D2086#86910, @bb wrote:

Didn't test it, but what happens now if minRange =~ maxRange, then it could be that the circumscribed circle for the minRange is bigger than the inscribed circle for maxRange...

Well, as soon as the unit gets in actual range, it will be detected by PossiblyAtDestination, and the entity will warn UnitAI that it's in range, and vice-versa.
So it would still work. Obviously this isn't a perfect situation.

But will it get in range? (I did not test it!!) If the minRange is so large the path might end outside the maxRange area and thus we never get there

wraitii added a comment.Jul 16 2019, 9:41 PM

This comment was removed by wraitii.

Add comment clarifying a pathological edge-case that one could run into.

Successful build - Chance fights ever on the side of the prudent.

Link to build: https://jenkins.wildfiregames.com/job/docker-differential/103/display/redirect

Harbormaster completed remote builds in B8402: Diff 8938.Jul 16 2019, 10:11 PM

This revision was not accepted when it landed; it landed in state Needs Review.Jul 17 2019, 8:08 PM

Closed by commit rP22495: Fix max-range approach when treating a target as a circle. (authored by wraitii). · Explain Why

This revision was automatically updated to reflect the committed changes.