Add production bathymetric sonar slice

game/world/sites/vehicle_test_environment.gd

@@ -1,8 +1,20 @@
 class_name VehicleTestEnvironment
 extends Node3D
 
+const TERRAIN_COLUMNS := 61
+const TERRAIN_ROWS := 69
+const TERRAIN_WIDTH_M := 180.0
+const TERRAIN_LENGTH_M := 200.0
+const TERRAIN_NEAR_Z := 28.0
+
 
 func _ready() -> void:
+	_add_bathymetric_terrain()
+	_place_calibration_target()
+	_add_suspended_particles()
+
+
+func _add_suspended_particles() -> void:
 	var particles := GPUParticles3D.new()
 	particles.name = "SuspendedParticles"
 	particles.position = Vector3(0.0, -34.0, -42.0)
@@ -31,3 +43,111 @@ func _ready() -> void:
 	particle_mesh.height = 0.07
 	particles.draw_pass_1 = particle_mesh
 	add_child(particles)
+
+
+func _add_bathymetric_terrain() -> void:
+	var surface := SurfaceTool.new()
+	surface.begin(Mesh.PRIMITIVE_TRIANGLES)
+	for row in range(TERRAIN_ROWS - 1):
+		for column in range(TERRAIN_COLUMNS - 1):
+			var top_left := _terrain_vertex(row, column)
+			var top_right := _terrain_vertex(row, column + 1)
+			var bottom_left := _terrain_vertex(row + 1, column)
+			var bottom_right := _terrain_vertex(row + 1, column + 1)
+			_add_terrain_triangle(surface, top_left, top_right, bottom_left)
+			_add_terrain_triangle(surface, top_right, bottom_right, bottom_left)
+	surface.generate_normals()
+	var mesh := surface.commit()
+
+	var body := StaticBody3D.new()
+	body.name = "BathymetricTerrain"
+	body.set_meta("sonar_material", 1)
+	body.set_meta("sonar_reflectivity", 0.72)
+	var mesh_instance := MeshInstance3D.new()
+	mesh_instance.name = "Mesh"
+	mesh_instance.mesh = mesh
+	var material := StandardMaterial3D.new()
+	material.albedo_color = Color(0.075, 0.19, 0.19)
+	material.roughness = 0.92
+	mesh_instance.material_override = material
+	body.add_child(mesh_instance)
+	var collision := CollisionShape3D.new()
+	collision.name = "Collision"
+	var height_map := HeightMapShape3D.new()
+	height_map.map_width = TERRAIN_COLUMNS
+	height_map.map_depth = TERRAIN_ROWS
+	var height_data := PackedFloat32Array()
+	height_data.resize(TERRAIN_COLUMNS * TERRAIN_ROWS)
+	for row in TERRAIN_ROWS:
+		for column in TERRAIN_COLUMNS:
+			var vertex := _terrain_vertex(row, column)
+			height_data[row * TERRAIN_COLUMNS + column] = vertex.y
+	height_map.map_data = height_data
+	collision.shape = height_map
+	collision.position = Vector3(
+		0.0,
+		0.0,
+		TERRAIN_NEAR_Z - TERRAIN_LENGTH_M * 0.5
+	)
+	collision.scale = Vector3(
+		TERRAIN_WIDTH_M / float(TERRAIN_COLUMNS - 1),
+		1.0,
+		TERRAIN_LENGTH_M / float(TERRAIN_ROWS - 1)
+	)
+	body.add_child(collision)
+	add_child(body)
+
+
+func _terrain_vertex(row: int, column: int) -> Vector3:
+	var x := lerpf(
+		-TERRAIN_WIDTH_M * 0.5,
+		TERRAIN_WIDTH_M * 0.5,
+		float(column) / float(TERRAIN_COLUMNS - 1)
+	)
+	var z := TERRAIN_NEAR_Z - (
+		TERRAIN_LENGTH_M * float(row) / float(TERRAIN_ROWS - 1)
+	)
+	return Vector3(x, _terrain_height(x, z), z)
+
+
+func _terrain_height(x: float, z: float) -> float:
+	var distance_ratio := clampf(
+		(TERRAIN_NEAR_Z - z) / TERRAIN_LENGTH_M,
+		0.0,
+		1.0
+	)
+	var base := lerpf(-40.0, -78.0, distance_ratio)
+	var left_ridge := 13.0 * exp(
+		-(pow(x + 24.0, 2.0) / 210.0 + pow(z + 48.0, 2.0) / 980.0)
+	)
+	var right_ridge := 15.0 * exp(
+		-(pow(x - 25.0, 2.0) / 250.0 + pow(z + 58.0, 2.0) / 1150.0)
+	)
+	var channel := -8.5 * exp(
+		-(pow(x, 2.0) / 120.0 + pow(z + 66.0, 2.0) / 2500.0)
+	)
+	var rear_rise := 8.0 * exp(
+		-(pow(x + 5.0, 2.0) / 900.0 + pow(z + 125.0, 2.0) / 620.0)
+	)
+	var undulation := 1.8 * sin(x * 0.075) * cos(z * 0.048)
+	return base + left_ridge + right_ridge + channel + rear_rise + undulation
+
+
+func _add_terrain_triangle(
+	surface: SurfaceTool,
+	a: Vector3,
+	b: Vector3,
+	c: Vector3
+) -> void:
+	surface.set_uv(Vector2(a.x, a.z) * 0.02)
+	surface.add_vertex(a)
+	surface.set_uv(Vector2(b.x, b.z) * 0.02)
+	surface.add_vertex(b)
+	surface.set_uv(Vector2(c.x, c.z) * 0.02)
+	surface.add_vertex(c)
+
+
+func _place_calibration_target() -> void:
+	var target := get_node_or_null("SonarCalibrationTarget") as Node3D
+	if target != null:
+		target.position.y = _terrain_height(target.position.x, target.position.z) + 2.5