feat: lazy loading of terrain chunk LODs

modules/terrain_editor/terrain_chunk.cpp

@@ -21,11 +21,21 @@ void TerrainChunk::ready() {
 	process_lod();
 }
 
+void TerrainChunk::generate_lod(size_t lod) {
+	MeshStatus status{ this->meshes.get(lod) };
+	size_t base_detail{ lod == 0 ? this->lod0_detail : this->lod0_detail / (2 * lod + lod) };
+	base_detail = base_detail > 1 ? base_detail : 1;
+	Vector3 const position{ get_global_position() };
+	this->generator->push_task({ { position.x, position.z }, { this->size, this->size } }, status.mesh, base_detail > 1 ? base_detail : 1, callable_mp(this, &self_type::lod_generated).bind(lod));
+	status.flag = MESH_DISPATCHED;
+	this->meshes.set(lod, status);
+}
+
 void TerrainChunk::on_terrain_changed() {
 	if (this->generator) {
-		Vector3 const position{ get_global_position() };
+		if (this->meshes.size() != this->lod_count) {
-		this->meshes.resize_initialized(3);
+			this->meshes.resize_initialized(this->lod_count);
-		size_t lod{ 0 };
+		}
 		if (this->collisions) {
 			this->collisions->queue_free();
 			this->collisions = nullptr;
@@ -34,28 +44,31 @@ void TerrainChunk::on_terrain_changed() {
 			if (!status.mesh.is_valid()) {
 				status.mesh.instantiate();
 			}
-			size_t base_detail{ lod == 0 ? this->lod0_detail : this->lod0_detail / (2 * lod) };
+			status.flag = MESH_DIRTY;
-			status.dirty = true;
-			this->generator->push_task({ { position.x, position.z }, { this->size, this->size } }, status.mesh, base_detail > 1 ? base_detail : 1, callable_mp(this, &self_type::lod_generated).bind(lod));
-			lod++;
 		}
+		generate_lod(this->meshes.size() - 1);
 	}
 }
 
 void TerrainChunk::lod_generated(size_t lod) {
-	this->meshes.set(lod, { this->meshes[lod].mesh, false });
+	this->meshes.set(lod, { this->meshes[lod].mesh, MESH_LOADED });
 }
 
 void TerrainChunk::process_lod() {
 	size_t result{ (size_t)this->meshes.size() };
 	if (is_ready() && this->meshes.size() > 0) {
 		Vector3 position{ get_global_position() };
+		position.y = 0;
 		Vector3 camera{ get_viewport()->get_camera_3d()->get_global_position() };
-		float distance{ (position - camera).length() - this->size / 2.f };
+		camera.y = 0;
+		float distance{ (position - camera).length() - this->size };
 		distance = distance > 0.f ? distance : 0.f;
-		size_t lod{ size_t(Math::floor(distance / (this->lod_end_distance / this->meshes.size()))) };
+		size_t lod{ size_t(Math::floor(distance / ((this->max_lod_distance * this->size) / this->meshes.size()))) };
 		result = lod < this->meshes.size() ? lod : (this->meshes.size() - 1);
-		while (this->meshes[result].dirty && result < (this->meshes.size() - 1)) {
+		if (this->meshes[result].flag == MESH_DIRTY) {
+			generate_lod(result);
+		}
+		while (this->meshes[result].flag != MESH_LOADED && result < (this->meshes.size() - 1)) {
 			result++;
 		}
 		if (this->meshes[result].mesh != this->get_mesh()) {

modules/terrain_editor/terrain_chunk.h

@@ -6,11 +6,17 @@ class TerrainMeshGenerator;
 
 class TerrainChunk : public MeshInstance3D {
 	GDCLASS(TerrainChunk, MeshInstance3D);
+	enum MeshStatusFlag {
+		MESH_DIRTY,
+		MESH_DISPATCHED,
+		MESH_LOADED
+	};
 	struct MeshStatus {
 		Ref<ArrayMesh> mesh;
-		bool dirty;
+		MeshStatusFlag flag;
 	};
 	static void _bind_methods();
+	void generate_lod(size_t lod);
 	void ready();
 	void on_terrain_changed();
 	void lod_generated(size_t lod);
@@ -27,10 +33,10 @@ public:
 
 private:
 	Node *collisions{ nullptr };
-	size_t collisions_lod{ 0 };
+	size_t lod_count{ 3 };
 	Vector<MeshStatus> meshes{};
 	int lod0_detail{ 200 };
-	float lod_end_distance{ 600 };
+	float max_lod_distance{ 6 };
 	float size{ 200 };
 	TerrainMeshGenerator *generator{ nullptr };
 };

project/objects/terrain_chunk.tscn

@@ -4,5 +4,5 @@
 
 [node name="TerrainChunk" type="TerrainChunk" unique_id=1453572398]
 material_override = ExtResource("1_6vjd7")
-size = 50.0
+size = 40.0
-lod0_detail = 100
+lod0_detail = 80

project/scenes/editor.tscn

@@ -31,6 +31,7 @@ noise = SubResource("FastNoiseLite_b1cmn")
 noise_amplitude = 5.0
 
 [sub_resource type="FastNoiseLite" id="FastNoiseLite_ba0ut"]
+frequency = 0.0163
 fractal_type = 2
 fractal_gain = 1.0
 fractal_weighted_strength = 0.58
@@ -132,7 +133,7 @@ load_path = "res://.godot/imported/point.svg-e68fd7c1e788d2c48d769cc58eba6e98.ct
 primitives = [SubResource("PointPrimitive_5tm2q"), SubResource("NoisePrimitive_ba0ut"), SubResource("NoisePrimitive_pxqd5"), SubResource("NoisePrimitive_q68jb"), SubResource("PlanePrimitive_ba0ut")]
 vertex_color_gradient = SubResource("Gradient_b1cmn")
 color_gradient_end_height = 100.0
-chunk_count = 4
+chunk_count = 8
 chunk_scene = ExtResource("1_pxqd5")
 point_primitive_object = ExtResource("1_b1cmn")
 
@@ -176,17 +177,6 @@ current_tab = 0
 layout_mode = 2
 metadata/_tab_index = 0
 
-[node name="Tree" type="PrimitiveLayerList" parent="LeftPanel/VBoxContainer/Layers/Layers" unique_id=797700186 node_paths=PackedStringArray("terrain")]
-layout_mode = 2
-size_flags_vertical = 3
-scroll_horizontal_enabled = false
-terrain = NodePath("../../../../../TerrainMeshEditor")
-icons = {
-&"NoisePrimitive": ExtResource("5_eqbpn"),
-&"PlanePrimitive": ExtResource("4_xg7d5"),
-&"PointPrimitive": ExtResource("4_5lcyj")
-}
-
 [node name="HBoxContainer" type="HBoxContainer" parent="LeftPanel/VBoxContainer/Layers/Layers" unique_id=702489990]
 layout_mode = 2
 size_flags_vertical = 8
@@ -222,6 +212,17 @@ expand_icon = true
 primitive_blueprint = SubResource("NoisePrimitive_5lcyj")
 terrain = NodePath("../../../../../../TerrainMeshEditor")
 
+[node name="Tree" type="PrimitiveLayerList" parent="LeftPanel/VBoxContainer/Layers/Layers" unique_id=797700186 node_paths=PackedStringArray("terrain")]
+layout_mode = 2
+size_flags_vertical = 3
+scroll_horizontal_enabled = false
+terrain = NodePath("../../../../../TerrainMeshEditor")
+icons = {
+&"NoisePrimitive": ExtResource("5_eqbpn"),
+&"PlanePrimitive": ExtResource("4_xg7d5"),
+&"PointPrimitive": ExtResource("4_5lcyj")
+}
+
 [node name="Inspector" type="TabContainer" parent="LeftPanel/VBoxContainer" unique_id=240272030]
 layout_mode = 2
 size_flags_vertical = 3