Drive basic trees from biome feature stages

internal/world/trees.go

@@ -0,0 +1,127 @@
+package world
+
+import "regionio/internal/worldgen"
+
+const vegetationStage = 9
+
+func placeVanillaTrees(c *Chunk, seed int64, cx, cz int32, biomes *[16][16]string, surfTop *[16][16]int) {
+	set, err := worldgen.LoadFeatureSet()
+	if err != nil {
+		panic(err)
+	}
+	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) <= vegetationStage {
+				continue
+			}
+			for featureIndex, name := range stages[vegetationStage] {
+				if seen[name] {
+					continue
+				}
+				seen[name] = true
+				placed, ok := set.Placed[name]
+				if !ok || !treeFeatureType(set.Configured[placed.Feature].Type) {
+					continue
+				}
+				plan, err := set.Placement(name)
+				if err != nil {
+					continue
+				}
+				random.SetFeatureSeed(decorationSeed, featureIndex, vegetationStage)
+				count := plan.Count.Sample(random)
+				for attempt := 0; attempt < count; attempt++ {
+					x, z := int(random.NextIntN(16)), int(random.NextIntN(16))
+					y := MinY + surfTop[x][z] + 1
+					placeTreeReference(c, set, random, placed.Feature, x, y, z)
+				}
+			}
+		}
+	}
+}
+
+func treeFeatureType(kind string) bool {
+	return kind == "minecraft:tree" || kind == "minecraft:random_selector"
+}
+
+func placeTreeReference(c *Chunk, set *worldgen.FeatureSet, random worldgen.RandomSource, name string, x, y, z int) bool {
+	configured, ok := set.Configured[name]
+	if !ok {
+		if placed, exists := set.Placed[name]; exists {
+			return placeTreeReference(c, set, random, placed.Feature, x, y, z)
+		}
+		return false
+	}
+	switch configured.Type {
+	case "minecraft:random_selector":
+		selector, err := set.RandomSelector(name)
+		if err != nil {
+			return false
+		}
+		for _, entry := range selector.Features {
+			if random.NextFloat() < entry.Chance {
+				return placeTreeReference(c, set, random, entry.Feature.Name, x, y, z)
+			}
+		}
+		return placeTreeReference(c, set, random, selector.Default.Name, x, y, z)
+	case "minecraft:tree":
+		config, err := set.Tree(name)
+		if err != nil || config.TrunkPlacer.Type != "minecraft:straight_trunk_placer" || config.FoliagePlacer.Type != "minecraft:blob_foliage_placer" {
+			return false
+		}
+		return placeStraightBlobTree(c, random, x, y, z, config)
+	}
+	return false
+}
+
+func placeStraightBlobTree(c *Chunk, random worldgen.RandomSource, x, y, z int, config worldgen.TreeFeatureConfig) bool {
+	if x < 2 || x >= 14 || z < 2 || z >= 14 || y <= MinY || y+12 >= MinY+WorldHeight {
+		return false
+	}
+	floor := c.GetBlock(x, y-1, z)
+	if floor != StateGrass && floor != StateDirt && floor != StateCoarseDirt && floor != StatePodzol {
+		return false
+	}
+	height := config.TrunkPlacer.BaseHeight
+	if config.TrunkPlacer.HeightRandA > 0 {
+		height += int(random.NextIntN(int32(config.TrunkPlacer.HeightRandA + 1)))
+	}
+	if config.TrunkPlacer.HeightRandB > 0 {
+		height += int(random.NextIntN(int32(config.TrunkPlacer.HeightRandB + 1)))
+	}
+	for dy := 0; dy <= height+config.FoliagePlacer.Height; dy++ {
+		if c.GetBlock(x, y+dy, z) != StateAir {
+			return false
+		}
+	}
+	logState, okLog := nameToStateID(config.TrunkProvider.State.Name, config.TrunkProvider.State.Properties)
+	leafState, okLeaf := nameToStateID(config.FoliageProvider.State.Name, config.FoliageProvider.State.Properties)
+	if !okLog || !okLeaf {
+		return false
+	}
+	c.SetBlock(x, y-1, z, StateDirt)
+	for dy := 0; dy < height; dy++ {
+		c.SetBlock(x, y+dy, z, logState)
+	}
+	centerY := y + height - 1 + config.FoliagePlacer.Offset
+	for layer := 0; layer < config.FoliagePlacer.Height; layer++ {
+		radius := config.FoliagePlacer.Radius
+		if layer == config.FoliagePlacer.Height-1 {
+			radius--
+		}
+		ly := centerY - layer
+		for dx := -radius; dx <= radius; dx++ {
+			for dz := -radius; dz <= radius; dz++ {
+				if abs(dx) == radius && abs(dz) == radius && random.NextIntN(2) == 0 {
+					continue
+				}
+				if c.GetBlock(x+dx, ly, z+dz) == StateAir {
+					c.SetBlock(x+dx, ly, z+dz, leafState)
+				}
+			}
+		}
+	}
+	return true
+}