map::find_clear_path returns invalid trajectory for some 3D cases

[olanti-p]

Describe the bug

When 3D FOV enabled, map::find_clear_path returns weird values when abs(dx) == dz or abs(dy) == dz

Steps To Reproduce

1. Move into a clear field
2. Run the improvised tests: map_fcp_bug.cpp
3. None of them fail, but 7 should

Expected behavior

map::find_clear_path returns a valid trajectory

Versions and configuration

• OS: Linux
  • OS Version: Description: Ubuntu 19.10; Release: 19.10; Codename: eoan;
• Game Version: f94cfe1 [64-bit]
• Graphics Version: Tiles
• Game Language: English [en]
• Mods loaded: [
  Dark Days Ahead [dda],
  Disable NPC Needs [no_npc_food],
  Magiclysm [magiclysm]
  ]

Additional context

I'm not familiar with CDDA's tests, but there doesn't seem to be any for map::find_clear_path.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions. Please do not 'bump' or comment on this issue unless you are actively working on it. Stale issues, and stale issues that are closed are still considered.

[kevingranade]

Should be fixed by #38730

[olanti-p]

Nope, still happens on current master. You can see it while aiming: the code basically calls g->m.find_clear_path(g->u.pos, dst) (where dst is cursor position) and draws returned trajectory. Try aiming 10 tiles north, 2 tiles west and 2 levels up - the trajectory shrinks to "2 tiles north, 2 tiles west, 2 levels up"

Could be related to / a dupe of #13601 btw

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions. Please do not 'bump' or comment on this issue unless you are actively working on it. Stale issues, and stale issues that are closed are still considered.