105 lines
3.6 KiB
GDScript
105 lines
3.6 KiB
GDScript
extends Node3D
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## Terrain generator — M0 placeholder.
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##
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## Builds ONE heightmap chunk from deterministic noise, so the world already
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## looks like rolling ground rather than a flat plane. Single chunk, generated at
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## _ready(). Chunk streaming, biomes and server-side determinism (see
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## docs/ARCHITECTURE.md §4) come in later milestones.
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##
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## The mesh is generated in code (no asset needed) so the project runs the moment
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## Godot opens it, with nothing to import.
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##
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## Exposes `sample_height(x, z)` so other systems (player spawn, prop placement)
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## can sit exactly on the surface instead of guessing a Y and falling through.
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signal ready_built ## emitted once the mesh + collision exist
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@export var size: int = 128 # chunk is size x size metres
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@export var resolution: int = 96 # vertices per side (higher = smoother/heavier)
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@export var height_scale: float = 10.0
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@export var noise_seed: int = 1337
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var _noise: FastNoiseLite
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var built: bool = false
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func _ready() -> void:
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_build()
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func _build() -> void:
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_noise = FastNoiseLite.new()
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_noise.seed = noise_seed
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_noise.noise_type = FastNoiseLite.TYPE_PERLIN
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_noise.frequency = 0.012
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_noise.fractal_octaves = 4
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var st := SurfaceTool.new()
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st.begin(Mesh.PRIMITIVE_TRIANGLES)
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var step := float(size) / float(resolution)
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var half := size * 0.5
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var uv_scale := 1.0 / float(size)
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# Build a grid of quads, two triangles each. Each vertex carries a planar UV
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# (world-XZ mapped to 0..1) so the surface is ready for texturing later.
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for z in range(resolution):
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for x in range(resolution):
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var x0 := x * step - half
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var z0 := z * step - half
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var x1 := (x + 1) * step - half
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var z1 := (z + 1) * step - half
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var p00 := Vector3(x0, sample_height(x0, z0), z0)
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var p10 := Vector3(x1, sample_height(x1, z0), z0)
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var p01 := Vector3(x0, sample_height(x0, z1), z1)
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var p11 := Vector3(x1, sample_height(x1, z1), z1)
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_add_tri(st, p00, p01, p11, half, uv_scale)
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_add_tri(st, p00, p11, p10, half, uv_scale)
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# Normals give the lighting its shape. Tangents are only needed for normal
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# maps, which this low-poly material doesn't use — so we skip them.
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st.generate_normals()
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var mesh := st.commit()
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var mi := MeshInstance3D.new()
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mi.name = "TerrainMesh"
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mi.mesh = mesh
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# Simple ground material. Low-poly look = flat-ish colour + lighting does the rest.
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var mat := StandardMaterial3D.new()
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mat.albedo_color = Color(0.33, 0.45, 0.22) # mossy green
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mat.roughness = 0.95
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mi.material_override = mat
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add_child(mi)
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# Collision so the player can walk on it. Build the body BEFORE marking built
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# so anything spawning on ready_built already has ground under it.
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var body := StaticBody3D.new()
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body.name = "TerrainBody"
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var shape := CollisionShape3D.new()
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shape.shape = mesh.create_trimesh_shape()
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body.add_child(shape)
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add_child(body)
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built = true
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ready_built.emit()
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## World-space ground height at (x, z). Safe to call before or after _build()
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## because it lazily creates the noise object.
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func sample_height(x: float, z: float) -> float:
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if _noise == null:
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_noise = FastNoiseLite.new()
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_noise.seed = noise_seed
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_noise.noise_type = FastNoiseLite.TYPE_PERLIN
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_noise.frequency = 0.012
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_noise.fractal_octaves = 4
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return _noise.get_noise_2d(x, z) * height_scale
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func _add_tri(st: SurfaceTool, a: Vector3, b: Vector3, c: Vector3, half: float, uv_scale: float) -> void:
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st.set_uv(Vector2((a.x + half) * uv_scale, (a.z + half) * uv_scale))
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st.add_vertex(a)
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st.set_uv(Vector2((b.x + half) * uv_scale, (b.z + half) * uv_scale))
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st.add_vertex(b)
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st.set_uv(Vector2((c.x + half) * uv_scale, (c.z + half) * uv_scale))
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st.add_vertex(c)
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