Animals stay off the cliffs (Gitea #6): nothing walks up or along ground steeper than 35 degrees, and a carcass on steep ground slides down to where it can be reached and butchered

scripts/creatures/creature.gd

@@ -92,6 +92,13 @@ const KINDS := {
 		"drops": {"raw_meat": [5, 7], "bear_hide": [1, 1], "bear_fat": [2, 3]}},
 }
 const CARCASS_SECONDS := 300.0
+## The steepest ground an animal walks up: 35 degrees (the ground's normal
+## at least this upright). The player's limit is about 45.
+const MAX_CLIMB_NY := 0.82
+const MAX_CLIMB_RISE := 0.7     ## (tan 35 degrees: metres up per metre along)
+## A carcass on ground steeper than this slides down to where it's flatter,
+## so it can be reached and butchered (Gitea #6).
+const CARCASS_REST_NY := 0.8
 
 var kind := "deer"
 var def: Dictionary
@@ -384,6 +391,18 @@ func _blocked(dir: Vector3) -> bool:
 		return true
 	if absf(h - global_position.y) > 1.1:
 		return true
+	# Nothing climbs steep ground, or walks along it (the mountain rim: Gitea
+	# #6). Going down it is fine, so one that's somehow up there can always
+	# come back.
+	if h > global_position.y - 0.3:
+		var run := Vector2(probe.x - global_position.x, probe.z - global_position.z).length()
+		if (h - global_position.y) > run * MAX_CLIMB_RISE:
+			return true
+		# The slope along the way: just ahead, halfway, and at the probe.
+		for f in [0.2, 0.5, 1.0]:
+			var s: Vector3 = global_position.lerp(probe, f)
+			if terrain.sample_normal(s.x, s.z).y < MAX_CLIMB_NY and terrain.sample_height(s.x, s.z) > global_position.y - 0.3 * f:
+				return true
 	# Trees, rocks and buildings at chest height (the terrain isn't on this test).
 	var from := global_position + Vector3(0, 0.45, 0)
 	var q := PhysicsRayQueryParameters3D.create(from, Vector3(probe.x, h + 0.45, probe.z), 1)
@@ -468,6 +487,7 @@ func _die(from: Vector3) -> void:
 	if puppet:
 		_visual.rotation.z = -PI * 0.5
 		return
+	_settle()
 	# Topple onto its side, away from the blow.
 	var side := 1.0 if (global_position - from).dot(global_basis.x) > 0.0 else -1.0
 	if is_inside_tree() and DisplayServer.get_name() != "headless":
@@ -477,6 +497,28 @@ func _die(from: Vector3) -> void:
 		_visual.rotation.z = -side * PI * 0.5
 	died.emit(self)
 
+## A carcass on steep ground (half into a cliff face, out of reach) slides
+## downhill, half a metre at a time, until the ground's flatter: up to 20 m,
+## and never out past the edge of the play area. Online the server does this
+## and players see it where it ends up.
+func _settle() -> void:
+	if terrain == null:
+		return
+	var p := global_position
+	for _i in range(40):
+		var n: Vector3 = terrain.sample_normal(p.x, p.z)
+		if n.y >= CARCASS_REST_NY:
+			break
+		var down := Vector3(n.x, 0.0, n.z)   # (a slope's normal leans downhill)
+		if down.length() < 0.001:
+			break
+		var q := p + down.normalized() * 0.5
+		if not terrain.inside_boundary(q.x, q.z, 1.0):
+			break
+		p = Vector3(q.x, terrain.sample_height(q.x, q.z), q.z)
+	if p.distance_to(global_position) > 0.01:
+		global_position = p
+
 ## What butchering gives (rolled once).
 func butcher_drops() -> Dictionary:
 	var out := {}