move data stuff

mc/data/multi_noise.go

@@ -0,0 +1,129 @@
+package data
+
+import (
+	"fmt"
+	"math"
+)
+
+// MultiNoisePreset names the two built-in multi-noise parameter lists.
+const (
+	MultiNoiseOverworld = "minecraft:overworld"
+	MultiNoiseNether    = "minecraft:nether"
+)
+
+// ParamRange is a single quantized parameter range [Min, Max].
+type ParamRange struct {
+	Min, Max int64
+}
+
+// ParameterPoint is a 6-D parameter box plus an offset used by Minecraft's
+// climate distance function.
+type ParameterPoint struct {
+	Biome           string
+	Temperature     ParamRange
+	Humidity        ParamRange
+	Continentalness ParamRange
+	Erosion         ParamRange
+	Depth           ParamRange
+	Weirdness       ParamRange
+	Offset          int64
+}
+
+// MultiNoiseData holds the parameter lists for each preset.
+type MultiNoiseData struct {
+	Presets map[string][]ParameterPoint
+}
+
+// raw JSON shapes.
+type rawParameter struct {
+	Temperature     [2]int64 `json:"temperature"`
+	Humidity        [2]int64 `json:"humidity"`
+	Continentalness [2]int64 `json:"continentalness"`
+	Erosion         [2]int64 `json:"erosion"`
+	Depth           [2]int64 `json:"depth"`
+	Weirdness       [2]int64 `json:"weirdness"`
+	Offset          float64  `json:"offset"`
+}
+
+type rawEntry struct {
+	Biome      string       `json:"biome"`
+	Parameters rawParameter `json:"parameters"`
+}
+
+type rawMultiNoise map[string][]rawEntry
+
+// LoadMultiNoise loads the expanded multi-noise parameter list for a Minecraft
+// version. The data is expected to be present under the
+// "multi_noise_biome_source_parameter_list" key in minecraft-data.
+func LoadMultiNoise(version string) (*MultiNoiseData, error) {
+	var raw rawMultiNoise
+	if err := LoadVersionedJson(version, "multi_noise_biome_source_parameter_list", &raw); err != nil {
+		return nil, fmt.Errorf("load multi_noise for %s: %w", version, err)
+	}
+
+	out := &MultiNoiseData{Presets: make(map[string][]ParameterPoint, len(raw))}
+	for preset, entries := range raw {
+		points := make([]ParameterPoint, len(entries))
+		for i, e := range entries {
+			points[i] = ParameterPoint{
+				Biome:           e.Biome,
+				Temperature:     ParamRange{Min: e.Parameters.Temperature[0], Max: e.Parameters.Temperature[1]},
+				Humidity:        ParamRange{Min: e.Parameters.Humidity[0], Max: e.Parameters.Humidity[1]},
+				Continentalness: ParamRange{Min: e.Parameters.Continentalness[0], Max: e.Parameters.Continentalness[1]},
+				Erosion:         ParamRange{Min: e.Parameters.Erosion[0], Max: e.Parameters.Erosion[1]},
+				Depth:           ParamRange{Min: e.Parameters.Depth[0], Max: e.Parameters.Depth[1]},
+				Weirdness:       ParamRange{Min: e.Parameters.Weirdness[0], Max: e.Parameters.Weirdness[1]},
+				Offset:          int64(math.Round(e.Parameters.Offset * 10000.0)),
+			}
+		}
+		out.Presets[preset] = points
+	}
+
+	return out, nil
+}
+
+// Lookup finds the biome whose parameter box is closest to the supplied
+// quantized climate parameters. The preset argument should be one of the
+// MultiNoise* constants.
+func (m *MultiNoiseData) Lookup(preset string, t, h, c, e, d, w int64) (string, error) {
+	points, ok := m.Presets[preset]
+	if !ok {
+		return "", fmt.Errorf("unknown multi-noise preset: %s", preset)
+	}
+
+	if len(points) == 0 {
+		return "", fmt.Errorf("multi-noise preset %s has no entries", preset)
+	}
+
+	bestBiome := ""
+	bestDist := int64(math.MaxInt64)
+
+	for _, p := range points {
+		dist := distanceToRange(t, p.Temperature) +
+			distanceToRange(h, p.Humidity) +
+			distanceToRange(c, p.Continentalness) +
+			distanceToRange(e, p.Erosion) +
+			distanceToRange(d, p.Depth) +
+			distanceToRange(w, p.Weirdness) +
+			p.Offset
+
+		if dist < bestDist {
+			bestDist = dist
+			bestBiome = p.Biome
+		}
+	}
+
+	return bestBiome, nil
+}
+
+func distanceToRange(value int64, r ParamRange) int64 {
+	if value < r.Min {
+		d := r.Min - value
+		return d * d
+	}
+	if value > r.Max {
+		d := value - r.Max
+		return d * d
+	}
+	return 0
+}