make world generation configurable

src/level/generation.rs

@@ -0,0 +1,93 @@
+use rand::Rng;
+use serde::{Deserialize, Serialize};
+
+use super::Level;
+
+/// enum for different kinds of level generation
+#[derive(Debug, Serialize, Deserialize)]
+#[serde(tag = "type")]
+pub enum LevelGeneration {
+	/// an empty level
+	Empty,
+	/// a level where every block up to the given height is randomized
+	FullRandom { height: usize },
+	/// a flat level with the given preset
+	Flat(FlatPreset),
+}
+
+/// enum for level presents
+#[derive(Debug, Serialize, Deserialize)]
+#[serde(tag = "flat_type")]
+pub enum FlatPreset {
+	/// the level is mostly stone, then dirt, then a layer of grass on the top
+	StoneAndGrass,
+	/// the level layers are custom as defined in server config
+	Custom { layers: Vec<FlatLayer> },
+}
+
+/// description of a flat world's layer
+#[derive(Debug, Serialize, Deserialize)]
+pub struct FlatLayer {
+	/// the block for the layer
+	pub block: u8,
+	/// the depth of the layer
+	pub depth: usize,
+}
+
+impl LevelGeneration {
+	/// generates the level
+	pub fn generate<R>(&self, level: &mut Level, rng: &mut R)
+	where
+		R: Rng,
+	{
+		match self {
+			Self::Empty => {}
+			Self::FullRandom { height } => {
+				let height = *height.min(&level.y_size);
+				for x in 0..level.x_size {
+					for y in 0..height {
+						for z in 0..level.z_size {
+							level.set_block(x, y, z, rng.gen_range(0..49));
+						}
+					}
+				}
+			}
+			Self::Flat(preset) => {
+				let custom_layers;
+				let layers_ref;
+
+				match preset {
+					FlatPreset::StoneAndGrass => {
+						custom_layers = vec![
+							FlatLayer {
+								block: 1,
+								depth: level.y_size / 2 - 4,
+							},
+							FlatLayer { block: 3, depth: 3 },
+							FlatLayer { block: 2, depth: 1 },
+						];
+						layers_ref = &custom_layers;
+					}
+					FlatPreset::Custom { layers } => {
+						layers_ref = layers;
+					}
+				}
+
+				let mut y = 0;
+				for layer in layers_ref {
+					for _ in 0..layer.depth {
+						for x in 0..level.x_size {
+							for z in 0..level.z_size {
+								level.set_block(x, y, z, layer.block);
+							}
+						}
+						y += 1;
+						if y >= level.y_size {
+							return;
+						}
+					}
+				}
+			}
+		}
+	}
+}