M0 scaffold: Godot 4 survival game skeleton + architecture/addon-SDK docs

scripts/world/terrain.gd

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+extends Node3D
+## Terrain generator — M0 placeholder.
+##
+## Builds ONE heightmap chunk from deterministic noise, so the world already
+## looks like rolling ground rather than a flat plane. This is intentionally
+## simple: a single chunk, generated at _ready(). Chunk streaming, biomes and
+## server-side determinism (see docs/ARCHITECTURE.md §4) come in later milestones.
+##
+## The mesh is generated in code (no asset needed) so the project runs the moment
+## Godot opens it, with nothing to import.
+
+@export var size: int = 128          # chunk is size x size metres
+@export var resolution: int = 96     # vertices per side (higher = smoother/heavier)
+@export var height_scale: float = 10.0
+@export var noise_seed: int = 1337
+
+func _ready() -> void:
+	_build()
+
+func _build() -> void:
+	var noise := FastNoiseLite.new()
+	noise.seed = noise_seed
+	noise.noise_type = FastNoiseLite.TYPE_PERLIN
+	noise.frequency = 0.012
+	noise.fractal_octaves = 4
+
+	var st := SurfaceTool.new()
+	st.begin(Mesh.PRIMITIVE_TRIANGLES)
+
+	var step := float(size) / float(resolution)
+	var half := size * 0.5
+
+	# Build a grid of quads, two triangles each.
+	for z in range(resolution):
+		for x in range(resolution):
+			var x0 := x * step - half
+			var z0 := z * step - half
+			var x1 := (x + 1) * step - half
+			var z1 := (z + 1) * step - half
+
+			var p00 := Vector3(x0, _height(noise, x0, z0), z0)
+			var p10 := Vector3(x1, _height(noise, x1, z0), z0)
+			var p01 := Vector3(x0, _height(noise, x0, z1), z1)
+			var p11 := Vector3(x1, _height(noise, x1, z1), z1)
+
+			_add_tri(st, p00, p01, p11)
+			_add_tri(st, p00, p11, p10)
+
+	st.generate_normals()
+	st.generate_tangents()
+
+	var mesh := st.commit()
+	var mi := MeshInstance3D.new()
+	mi.mesh = mesh
+
+	# Simple ground material. Low-poly look = flat-ish colour + lighting does the rest.
+	var mat := StandardMaterial3D.new()
+	mat.albedo_color = Color(0.33, 0.45, 0.22)   # mossy green
+	mat.roughness = 0.95
+	mi.material_override = mat
+	add_child(mi)
+
+	# Collision so the player can walk on it.
+	var body := StaticBody3D.new()
+	var shape := CollisionShape3D.new()
+	var col := mesh.create_trimesh_shape()
+	shape.shape = col
+	body.add_child(shape)
+	add_child(body)
+
+func _height(noise: FastNoiseLite, x: float, z: float) -> float:
+	return noise.get_noise_2d(x, z) * height_scale
+
+func _add_tri(st: SurfaceTool, a: Vector3, b: Vector3, c: Vector3) -> void:
+	st.add_vertex(a)
+	st.add_vertex(b)
+	st.add_vertex(c)