Place biome-driven water and lava springs

internal/world/springs.go

@@ -0,0 +1,92 @@
+package world
+
+import "regionio/internal/worldgen"
+
+const fluidsStage = 8
+
+func placeVanillaSprings(c *Chunk, seed int64, cx, cz int32, biomes *[16][16]string) {
+	set, err := worldgen.LoadFeatureSet()
+	if err != nil {
+		panic("world: loading feature datapack: " + err.Error())
+	}
+	random, decorationSeed := worldgen.DecorationRandom(seed, int(cx), int(cz))
+	seen := make(map[string]bool)
+	for bx := 0; bx < 16; bx += 4 {
+		for bz := 0; bz < 16; bz += 4 {
+			stages := set.Biomes[biomes[bx][bz]].Features
+			if len(stages) <= fluidsStage {
+				continue
+			}
+			for featureIndex, name := range stages[fluidsStage] {
+				if seen[name] {
+					continue
+				}
+				seen[name] = true
+				placed, ok := set.Placed[name]
+				if !ok {
+					continue
+				}
+				configured, ok := set.Configured[placed.Feature]
+				if !ok || configured.Type != "minecraft:spring_feature" {
+					continue
+				}
+				config, err := set.Spring(placed.Feature)
+				if err != nil {
+					panic(err)
+				}
+				plan, err := set.Placement(name)
+				if err != nil {
+					panic(err)
+				}
+				random.SetFeatureSeed(decorationSeed, featureIndex, fluidsStage)
+				for attempt := 0; attempt < plan.Count.Sample(random); attempt++ {
+					x := int(random.NextIntN(16))
+					z := int(random.NextIntN(16))
+					y := plan.SampleY(random, MinY, WorldHeight)
+					placeSpring(c, x, y, z, config)
+				}
+			}
+		}
+	}
+}
+
+func placeSpring(c *Chunk, x, y, z int, config worldgen.SpringFeatureConfig) {
+	valid := make(map[uint16]bool, len(config.ValidBlocks))
+	for _, name := range config.ValidBlocks {
+		if state, ok := nameToStateID(name, nil); ok {
+			valid[state] = true
+		}
+	}
+	state, ok := springStateID(config.State)
+	if !ok || !valid[c.GetBlock(x, y+1, z)] {
+		return
+	}
+	if config.RequiresBlockBelow && !valid[c.GetBlock(x, y-1, z)] {
+		return
+	}
+	rock := 0
+	holes := 0
+	for _, offset := range [][3]int{{-1, 0, 0}, {1, 0, 0}, {0, 0, -1}, {0, 0, 1}, {0, -1, 0}} {
+		nx, ny, nz := x+offset[0], y+offset[1], z+offset[2]
+		if nx < 0 || nx >= 16 || nz < 0 || nz >= 16 {
+			return
+		}
+		if valid[c.GetBlock(nx, ny, nz)] {
+			rock++
+		} else if c.GetBlock(nx, ny, nz) == StateAir {
+			holes++
+		}
+	}
+	if rock != config.RockCount || holes != config.HoleCount {
+		return
+	}
+	c.SetBlock(x, y, z, state)
+}
+
+func springStateID(state worldgen.BlockState) (uint16, bool) {
+	props := state.Properties
+	if (state.Name == "minecraft:water" || state.Name == "minecraft:lava") && props["falling"] == "true" {
+		props = map[string]string{"level": "8"}
+	}
+	return nameToStateID(state.Name, props)
+}