experiment: LivingPlane - GPU wave-equation height field reacting to a moving sphere (L162)

Standalone EGL/OpenGL 4.3 compute runner (runtime GLSL, no shader compiler needed), ping-pong height/velocity field,
damped wave + foundation spring + Gaussian sphere push + optional breathing, vertex-displaced render to PNG.
Independent of generation. Intel ADL GT2: ~0.08 ms/step at 512^2, ~0.29 ms/step at 1024^2 (wall-time difference).
.gitignore now allows Experiments/.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016dhxM43dnWvUu2B5Ph1iG1

Experiments/LivingPlane/UNREAL-MAPPING.md

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+# Unreal mapping note
+
+The prototype stores a two-channel height and vertical-velocity field in a pair of
+`RG32F` textures. A world-owned Unreal component could keep equivalent transient
+render graph textures and advance them with a compute pass. It should own simulation
+time and clear or restore its buffers when the world is recreated.
+
+The sphere path becomes a world-space interaction event: position, contact radius,
+and impulse strength are supplied to the compute pass. For multiplayer or deterministic
+replay, replicate the compact events and simulation tick, or record the resulting field;
+do not assume that independent GPU floating-point runs will produce byte-identical
+textures.
+
+The rendered top surface can remain a render-only displaced mesh. If it must participate
+in voxel collision or queries, its height must also reach the density evaluator. For a
+height `h(x,y)`, the plugin's density convention is negative inside solid and positive
+in air, so the plane's signed density is `z - h(x,y)`. Keep this calculation in metres
+until the existing voxel/Core boundary converts with the active voxel size (25 cm by
+default); do not mix metre distances and voxel counts in the wave solver.
+
+The current sample is an isolated visual field. Wiring this into `AVoxelWorld` would
+need an explicit owner for simulation lifetime, collision/update cadence, save/load,
+and the replication policy before it could affect shipped terrain.