resource: implement water/foliage/grass color computation

Cargo.lock

@@ -268,6 +268,12 @@ dependencies = [
  "miniz_oxide",
 ]
 
+[[package]]
+name = "glam"
+version = "0.24.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ad83ab008a4fa3b31dfa713dd41b5a9bdea1e94e4cf1e2fc274ffbd49b0271d3"
+
 [[package]]
 name = "heck"
 version = "0.4.1"
@@ -368,6 +374,7 @@ dependencies = [
  "enumflags2",
  "fastnbt",
  "flate2",
+ "glam",
  "image",
  "itertools",
  "num-integer",

Cargo.toml

@@ -15,6 +15,7 @@ clap = { version = "4.1.4", features = ["derive"] }
 enumflags2 = "0.7.5"
 fastnbt = "2.3.2"
 flate2 = "1.0.25"
+glam = "0.24.0"
 image = { version = "0.24.5", default-features = false, features = ["png"] }
 itertools = "0.10.5"
 num-integer = "0.1.45"

src/resource/biomes.rs

@@ -60,6 +60,18 @@ impl Biome {
 			..self
 		}
 	}
+
+	fn decode(val: i8) -> f32 {
+		f32::from(val) / 20.0
+	}
+
+	pub fn temp(&self) -> f32 {
+		Self::decode(self.temp)
+	}
+
+	pub fn downfall(&self) -> f32 {
+		Self::decode(self.downfall)
+	}
 }
 
 // Data extracted from Minecraft code decompiled using https://github.com/Hexeption/MCP-Reborn

src/resource/block_color.rs

@@ -1,10 +1,95 @@
-use super::{Biome, BlockType};
+use super::{Biome, BlockType, Color};
 
-pub fn block_color(block: BlockType, _biome: &Biome, depth: f32) -> [u8; 4] {
-	let h = 0.5 + 0.005 * depth;
-	let c = block
-		.color
-		.0
-		.map(|v| (f32::from(v) * h).clamp(0.0, 255.0) as u8);
-	[c[0], c[1], c[2], 255]
+use glam::Vec3;
+
+fn color_vec(color: Color) -> Vec3 {
+	Vec3::from_array(color.0.map(f32::from))
+}
+
+fn color_from_params(colors: &[Vec3; 3], biome: &Biome, depth: f32) -> Vec3 {
+	let temp = (biome.temp() - f32::max((depth - 64.0) / 600.0, 0.0)).clamp(0.0, 1.0);
+	let downfall = biome.downfall().clamp(0.0, 1.0) * temp;
+
+	colors[0] + temp * colors[1] + downfall * colors[2]
+}
+
+trait BiomeExt {
+	fn grass_color(&self, depth: f32) -> Vec3;
+	fn foliage_color(&self, depth: f32) -> Vec3;
+	fn water_color(&self) -> Vec3;
+}
+
+impl BiomeExt for Biome {
+	fn grass_color(&self, depth: f32) -> Vec3 {
+		const GRASS_COLORS: [Vec3; 3] = [
+			Vec3::new(0.502, 0.706, 0.592),   // lower right
+			Vec3::new(0.247, 0.012, -0.259),  // lower left - lower right
+			Vec3::new(-0.471, 0.086, -0.133), // upper left - lower left
+		];
+
+		self.grass_color
+			.map(color_vec)
+			.unwrap_or_else(|| color_from_params(&GRASS_COLORS, self, depth))
+	}
+
+	fn foliage_color(&self, depth: f32) -> Vec3 {
+		use super::BiomeGrassColorModifier::*;
+
+		const FOLIAGE_COLORS: [Vec3; 3] = [
+			Vec3::new(0.502, 0.706, 0.592),   // lower right
+			Vec3::new(0.247, 0.012, -0.259),  // lower left - lower right
+			Vec3::new(-0.471, 0.086, -0.133), // upper left - lower left
+		];
+		const DARK_FOREST_COLOR: Vec3 = Vec3::new(0.157, 0.204, 0.039); // == color_vec(Color([40, 52, 10]))
+		const SWAMP_FOLIAGE_COLOR: Vec3 = Vec3::new(0.416, 0.439, 0.224); // == color_vec(Color([106, 112, 57]))
+
+		let regular_color = || {
+			self.foliage_color
+				.map(color_vec)
+				.unwrap_or_else(|| color_from_params(&FOLIAGE_COLORS, self, depth))
+		};
+
+		match self.grass_color_modifier {
+			Some(DarkForest) => 0.5 * (regular_color() + DARK_FOREST_COLOR),
+			Some(Swamp) => SWAMP_FOLIAGE_COLOR,
+			None => regular_color(),
+		}
+	}
+
+	fn water_color(&self) -> Vec3 {
+		const DEFAULT_WATER_COLOR: Vec3 = Vec3::new(0.247, 0.463, 0.894); // == color_vec(Color([63, 118, 228]))
+
+		self.water_color
+			.map(color_vec)
+			.unwrap_or(DEFAULT_WATER_COLOR)
+	}
+}
+
+const BIRCH_COLOR: Vec3 = Vec3::new(0.502, 0.655, 0.333); // == color_vec(Color([128, 167, 85]))
+const EVERGREEN_COLOR: Vec3 = Vec3::new(0.380, 0.600, 0.380); // == color_vec(Color([97, 153, 97]))
+
+pub fn block_color(block: BlockType, biome: &Biome, depth: f32) -> [u8; 4] {
+	use super::BlockFlag::*;
+
+	let mut color = color_vec(block.color);
+
+	if block.is(Grass) {
+		color *= biome.grass_color(depth);
+	}
+	if block.is(Foliage) {
+		color *= biome.foliage_color(depth);
+	}
+	if block.is(Birch) {
+		color *= BIRCH_COLOR;
+	}
+	if block.is(Spruce) {
+		color *= EVERGREEN_COLOR;
+	}
+	if block.is(Water) {
+		color *= biome.water_color();
+	}
+
+	color *= 0.5 + 0.005 * depth;
+
+	[color[0] as u8, color[1] as u8, color[2] as u8, 255]
 }

src/resource/mod.rs

@@ -90,7 +90,7 @@ impl BlockTypes {
 	}
 }
 
-pub use biomes::Biome;
+pub use biomes::{Biome, BiomeGrassColorModifier};
 pub use block_color::block_color;
 
 #[derive(Debug)]