Drive basic trees from biome feature stages

internal/world/store.go

@@ -33,7 +33,7 @@ const dataVersion26 = 4790
 // first time it ran: chunkAt prefers the store over the generator, so the
 // already-explored area around spawn keeps its old terrain and every later fix
 // looks like it did nothing in exactly the place you are standing.
-const generatorVersion = 14
+const generatorVersion = 15
 
 // generatorVersionTag is the NBT key holding generatorVersion. It is namespaced
 // because it is ours, not part of the vanilla chunk format.

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
+}

internal/world/trees_test.go

@@ -0,0 +1,61 @@
+package world
+
+import (
+	"testing"
+
+	"regionio/internal/worldgen"
+)
+
+func TestStraightBlobTreeFromDatapack(t *testing.T) {
+	set, err := worldgen.LoadFeatureSet()
+	if err != nil {
+		t.Fatal(err)
+	}
+	config, err := set.Tree("minecraft:oak")
+	if err != nil {
+		t.Fatal(err)
+	}
+	chunk := NewChunk(0, 0, BiomePlains)
+	chunk.setBlockRaw(8, 63, 8, StateGrass)
+	if !placeStraightBlobTree(chunk, worldgen.NewLegacy(42), 8, 64, 8, config) {
+		t.Fatal("datapack oak placement failed")
+	}
+	logs, leaves := 0, 0
+	for y := 64; y < 80; y++ {
+		for x := 0; x < 16; x++ {
+			for z := 0; z < 16; z++ {
+				switch chunk.GetBlock(x, y, z) {
+				case StateOakLog:
+					logs++
+				case StateOakLeaf:
+					leaves++
+				}
+			}
+		}
+	}
+	if logs < 4 || leaves < 10 {
+		t.Fatalf("tree has %d logs and %d leaves", logs, leaves)
+	}
+}
+
+func TestBiomeTreeStageProducesTrees(t *testing.T) {
+	gen := NewVanillaGenerator(12345)
+	trees := 0
+	for cx := int32(-12); cx <= 12; cx += 3 {
+		for cz := int32(-12); cz <= 12; cz += 3 {
+			chunk := gen(cx, cz)
+			for y := SeaLevel; y < 160; y++ {
+				for x := 0; x < 16; x++ {
+					for z := 0; z < 16; z++ {
+						if chunk.GetBlock(x, y, z) == StateOakLog {
+							trees++
+						}
+					}
+				}
+			}
+		}
+	}
+	if trees == 0 {
+		t.Fatal("biome vegetation stages produced no oak logs")
+	}
+}

internal/world/vanilla.go

@@ -480,50 +480,15 @@ func decorate(c *Chunk, od *worldgen.OverworldDensity, cx, cz int32, seed int64,
 
 	placeVanillaOres(c, seed, cx, cz, biomeName)
 	placeVanillaSprings(c, seed, cx, cz, biomeName)
+	placeVanillaTrees(c, seed, cx, cz, biomeName, surfTop)
 	placeFlora(c, &r, surfTop, grass, biomeName)
 	placeDesertFeatures(c, &r, surfTop, biomeName)
 	placeRocks(c, &r, surfTop, grass, biomeName)
 
-	const attempts = 8
-	for a := 0; a < attempts; a++ {
-		lx := 2 + int(r.next()%12)
-		lz := 2 + int(r.next()%12)
-		if !grass[lx][lz] {
-			continue
-		}
-		baseY := MinY + surfTop[lx][lz] + 1
-		placeOak(c, lx, baseY, lz, &r)
-	}
-
 	// Place large structures like villages and strongholds
 	worldgen.PlaceStructures(c, od, cx, cz, seed, surfTop, biomeName)
 }
 
-func placeOak(c *Chunk, lx, baseY, lz int, r *chunkRand) {
-	h := 4 + int(r.next()%3) // trunk height 4..6
-	for i := 0; i < h; i++ {
-		c.SetBlock(lx, baseY+i, lz, StateOakLog)
-	}
-	topY := baseY + h - 1
-	// Canopy: two wide layers around the top, then two narrow layers above.
-	layers := []struct {
-		dy, radius int
-	}{{-1, 2}, {0, 2}, {1, 1}, {2, 1}}
-	for _, ly := range layers {
-		y := topY + ly.dy
-		for dx := -ly.radius; dx <= ly.radius; dx++ {
-			for dz := -ly.radius; dz <= ly.radius; dz++ {
-				if ly.radius == 2 && abs(dx) == 2 && abs(dz) == 2 {
-					continue // trim the far corners for a rounder shape
-				}
-				if c.GetBlock(lx+dx, y, lz+dz) == StateAir {
-					c.SetBlock(lx+dx, y, lz+dz, StateOakLeaf)
-				}
-			}
-		}
-	}
-}
-
 func abs(v int) int {
 	if v < 0 {
 		return -v

internal/worldgen/features.go

@@ -61,6 +61,44 @@ type SpringFeatureConfig struct {
 	ValidBlocks        []string   `json:"valid_blocks"`
 }
 
+type TreeFeatureConfig struct {
+	TrunkProvider struct {
+		Type  string     `json:"type"`
+		State BlockState `json:"state"`
+	} `json:"trunk_provider"`
+	FoliageProvider struct {
+		Type  string     `json:"type"`
+		State BlockState `json:"state"`
+	} `json:"foliage_provider"`
+	TrunkPlacer struct {
+		Type        string `json:"type"`
+		BaseHeight  int    `json:"base_height"`
+		HeightRandA int    `json:"height_rand_a"`
+		HeightRandB int    `json:"height_rand_b"`
+	} `json:"trunk_placer"`
+	FoliagePlacer struct {
+		Type   string `json:"type"`
+		Height int    `json:"height"`
+		Offset int    `json:"offset"`
+		Radius int    `json:"radius"`
+	} `json:"foliage_placer"`
+}
+
+type FeatureRef struct {
+	Name      string
+	Placement []PlacementModifier
+}
+
+type RandomSelectorConfig struct {
+	Default  FeatureRef
+	Features []RandomSelectorEntry
+}
+
+type RandomSelectorEntry struct {
+	Chance  float32
+	Feature FeatureRef
+}
+
 type BlockState struct {
 	Name       string            `json:"Name"`
 	Properties map[string]string `json:"Properties"`
@@ -76,6 +114,11 @@ type PlacementPlan struct {
 
 type CountProvider struct {
 	Min, Max int
+	Weighted []WeightedInt
+}
+
+type WeightedInt struct {
+	Value, Weight int
 }
 
 type HeightProvider struct {
@@ -85,6 +128,22 @@ type HeightProvider struct {
 }
 
 func (p CountProvider) Sample(r RandomSource) int {
+	if len(p.Weighted) > 0 {
+		total := 0
+		for _, entry := range p.Weighted {
+			total += entry.Weight
+		}
+		if total <= 0 {
+			return 0
+		}
+		roll := int(r.NextIntN(int32(total)))
+		for _, entry := range p.Weighted {
+			if roll < entry.Weight {
+				return entry.Value
+			}
+			roll -= entry.Weight
+		}
+	}
 	if p.Max <= p.Min {
 		return p.Min
 	}
@@ -181,6 +240,74 @@ func (s *FeatureSet) Spring(name string) (SpringFeatureConfig, error) {
 	return config, nil
 }
 
+func (s *FeatureSet) Tree(name string) (TreeFeatureConfig, error) {
+	configured, ok := s.Configured[name]
+	if !ok || configured.Type != "minecraft:tree" {
+		return TreeFeatureConfig{}, fmt.Errorf("worldgen: %s is not a tree feature", name)
+	}
+	var config TreeFeatureConfig
+	if err := json.Unmarshal(configured.Config, &config); err != nil {
+		return TreeFeatureConfig{}, fmt.Errorf("worldgen: decode %s: %w", name, err)
+	}
+	if config.TrunkPlacer.Type == "" || config.FoliagePlacer.Type == "" || config.TrunkProvider.State.Name == "" || config.FoliageProvider.State.Name == "" {
+		return TreeFeatureConfig{}, fmt.Errorf("worldgen: invalid tree config %s", name)
+	}
+	return config, nil
+}
+
+func (s *FeatureSet) RandomSelector(name string) (RandomSelectorConfig, error) {
+	configured, ok := s.Configured[name]
+	if !ok || configured.Type != "minecraft:random_selector" {
+		return RandomSelectorConfig{}, fmt.Errorf("worldgen: %s is not a random selector", name)
+	}
+	var raw struct {
+		Default  json.RawMessage `json:"default"`
+		Features []struct {
+			Chance  float32         `json:"chance"`
+			Feature json.RawMessage `json:"feature"`
+		} `json:"features"`
+	}
+	if err := json.Unmarshal(configured.Config, &raw); err != nil {
+		return RandomSelectorConfig{}, err
+	}
+	selector := RandomSelectorConfig{Features: make([]RandomSelectorEntry, len(raw.Features))}
+	var err error
+	selector.Default, err = parseFeatureRef(raw.Default)
+	if err != nil {
+		return RandomSelectorConfig{}, err
+	}
+	for i, entry := range raw.Features {
+		selector.Features[i].Chance = entry.Chance
+		selector.Features[i].Feature, err = parseFeatureRef(entry.Feature)
+		if err != nil {
+			return RandomSelectorConfig{}, err
+		}
+	}
+	return selector, nil
+}
+
+func parseFeatureRef(raw json.RawMessage) (FeatureRef, error) {
+	var name string
+	if err := json.Unmarshal(raw, &name); err == nil {
+		return FeatureRef{Name: name}, nil
+	}
+	var inline struct {
+		Feature   string            `json:"feature"`
+		Placement []json.RawMessage `json:"placement"`
+	}
+	if err := json.Unmarshal(raw, &inline); err != nil || inline.Feature == "" {
+		return FeatureRef{}, fmt.Errorf("worldgen: invalid feature reference %s", raw)
+	}
+	ref := FeatureRef{Name: inline.Feature, Placement: make([]PlacementModifier, len(inline.Placement))}
+	for i, modifier := range inline.Placement {
+		if err := json.Unmarshal(modifier, &ref.Placement[i]); err != nil {
+			return FeatureRef{}, err
+		}
+		ref.Placement[i].Raw = modifier
+	}
+	return ref, nil
+}
+
 func (s *FeatureSet) Placement(name string) (PlacementPlan, error) {
 	placed, ok := s.Placed[name]
 	if !ok {
@@ -233,7 +360,9 @@ func (s *FeatureSet) Placement(name string) (PlacementPlan, error) {
 				return PlacementPlan{}, fmt.Errorf("worldgen: %s unsupported height distribution %q", name, value.Height.Type)
 			}
 			plan.HeightDistribution, plan.MinY, plan.MaxY = value.Height.Type, min, max
-		case "minecraft:in_square", "minecraft:biome":
+		case "minecraft:in_square", "minecraft:biome", "minecraft:surface_water_depth_filter",
+			"minecraft:heightmap", "minecraft:block_predicate_filter", "minecraft:noise_threshold_count",
+			"minecraft:random_offset":
 			// Coordinate spreading and biome validation are applied by the world
 			// executor. Keeping them in the parsed plan preserves their order.
 		default:
@@ -253,10 +382,26 @@ func parseIntProvider(raw json.RawMessage) (CountProvider, error) {
 		Min  int    `json:"min_inclusive"`
 		Max  int    `json:"max_inclusive"`
 	}
-	if err := json.Unmarshal(raw, &uniform); err != nil || uniform.Type != "minecraft:uniform" {
-		return CountProvider{}, fmt.Errorf("unsupported count provider %s", raw)
+	if err := json.Unmarshal(raw, &uniform); err == nil && uniform.Type == "minecraft:uniform" {
+		return CountProvider{Min: uniform.Min, Max: uniform.Max}, nil
 	}
-	return CountProvider{Min: uniform.Min, Max: uniform.Max}, nil
+	var weighted struct {
+		Type         string `json:"type"`
+		Distribution []struct {
+			Data   int `json:"data"`
+			Weight int `json:"weight"`
+		} `json:"distribution"`
+	}
+	if err := json.Unmarshal(raw, &weighted); err == nil && weighted.Type == "minecraft:weighted_list" {
+		provider := CountProvider{Weighted: make([]WeightedInt, 0, len(weighted.Distribution))}
+		for _, entry := range weighted.Distribution {
+			if entry.Weight > 0 {
+				provider.Weighted = append(provider.Weighted, WeightedInt{Value: entry.Data, Weight: entry.Weight})
+			}
+		}
+		return provider, nil
+	}
+	return CountProvider{}, fmt.Errorf("unsupported count provider %s", raw)
 }
 
 func parseFeatureHeight(raw json.RawMessage) (HeightProvider, error) {