Adds OcclusionPolicy resource and wires it into IsometricFollowCamera.
Each _process frame, iterative rays from the camera eye to the player
focus detect bodies tagged "occluder"; their MeshInstance3D surfaces are
overridden with a transparent StandardMaterial3D (fade_alpha=0.25, instant).
Materials restore when the body clears the ray. Null-material surfaces
(e.g. the prototype Obstacle with no material assigned) receive a plain
transparent StandardMaterial3D so they fade correctly.
- client/scripts/occlusion_policy.gd — new Resource (enabled, fade_alpha,
occluder_group, occluder_collision_mask, max_occluder_cast_depth,
occluder_count_log_threshold, is_valid)
- client/resources/isometric_occlusion_policy.tres — default instance
- client/scripts/isometric_follow_camera.gd — occlusion_policy export,
_update_occlusion pipeline, _apply_occluder_fade/_restore_occluder helpers,
static occlusion_policy_is_valid guard, _exit_tree cleanup
- client/scenes/main.tscn — Obstacle tagged "occluder", policy assigned
- client/test/occlusion_policy_test.gd — new GdUnit4 unit tests
- client/test/isometric_follow_camera_test.gd — policy guard static tests
- docs/decomposition/modules/E1_M2_IsometricCameraController.md — NEON-27
snapshot + readability demo gate note
- docs/plans/NEON-27-implementation-plan.md — null-material decision recorded
VinPropane