gauges: reconstruct headingPointer -- the rotating compass + heading readout [widget recon 2]

The visible money-shot: a green compass needle that rotates with the mech's
facing plus a numeric heading in whole degrees (render-verified: the needle
swung and the number went 247 -> 182 as the mech turned).

Full class reconstruction from the binary (Make/ctor/dtor/TestInstance/
ShowInstance/BecameActive/Execute). Ghidra dropped the x87 float math feeding
Execute's needle endpoints and the ctor's NumericDisplay centering, so it was
recovered by disassembling BTL4OPT.EXE with capstone (scratchpad/disas_hp.py):
the needle is a radial line from innerRadius(20) to outerRadius(39) at the
heading angle, endpoints rounded half-up; the readout is round(360 - deg).

Two corrections vs the map:
- The header ctor was 12 args; the binary's is 14 -- widened it. Fields @0x98/
  @0x9C are the needle's inner/outer RADIUS (Execute multiplies them by sin/cos),
  not "color/spacing" as the old field names implied; renamed accordingly.
- ENGINE-CONVENTION FIX: the binary read the heading from EulerAngles index [0],
  but the WinTesla EulerAngles(Quaternion) decomposition is ambiguous for a
  yawing mech (the quaternion double-cover flips it to a pitch=roll=pi branch as
  yaw sweeps past +/-pi -> the needle spins erratically). Switched to
  YawPitchRoll, whose yaw-first .yaw is the clean continuous heading
  (pitch=roll~0). Faithful to the binary's intent (heading), correct for this
  engine's decomposition.

renderer->GetLinkedEntity() resolves the viewpoint mech (a GetViewpointEntity
fallback is kept belt-and-braces). Deps (NumericDisplay/GraphicsViewRecord/
GraphicGauge) are real engine classes -> no /FORCE risk; verified no unresolved
HeadingPointer externals, no parse desync, combat un-regressed (TARGET
DESTROYED, 0 crashes). Details + the disasm technique: docs/GAUGE_COMPOSITE.md.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

This commit is contained in:

arcattack

2026-07-06 16:05:47 -05:00

co-authored by

Claude Opus 4.8

parent 547f25e043

commit e869b00181

4 changed files with 290 additions and 40 deletions

									
										game/reconstructed/btl4grnd.cpp
									
		+1
		
												View File
												
				@@ -130,6 +130,7 @@ MethodDescription

							// to the engine base table L4MethodDescription).

							//

							&ColorMapperHeat::methodDescription,	// "cmHeat" -- heat-driven palette tint

							&HeadingPointer::methodDescription,		// "headingPointer" -- compass needle + heading

							&BTL4ChainToPrevious

						};