RegionIO/internal/world/surface_verify_test.go
Master290 4dcf938a85 Biome-aware surface rules from the vanilla rule tree
Replaces the biome-blind fillVanillaColumn heuristics with a full
interpreter for the overworld surface_rule tree (already embedded in
overworld.json): block/sequence/condition/bandlands rules plus all 11
condition tests (biome, steep, hole, water, temperature, y_above,
stone_depth, noise_threshold, not, vertical_gradient,
above_preliminary_surface).

- worldgen/blockids.go: name(+Properties)→network-ID table for surface
  blocks (grass/sand/terracotta/mycelium/podzol/coarse_dirt/sandstone/
  calcite/snow/ice/...), with snowy property variants.
- worldgen/surface.go: rule-tree parser + interpreter + SurfaceContext;
  LoadOverworldSurfaceRule caches the seed-independent tree.
- loader.go: OverworldDensity.SurfaceRule() exposes the parsed tree.
- biome_lookup.go: BiomeNameAt returns the biome name for biome tests.
- vanilla.go: samples the 2D climate + biome before column fill, threads
  the rule tree and biome name into fillVanillaColumn, and applies it
  top-down with stone as the default for non-matching (deeper) blocks.
  The above_preliminary_surface gate uses an inclusive bound so the top
  solid block reaches the biome dispatch.
- Performance: one per-column RNG and a reused SurfaceContext keep the
  overhead to ~+13ms/chunk (71ms vs 58ms baseline), within the gate.
2026-06-24 19:44:07 +03:00

56 lines
1.7 KiB
Go

package world
import (
"testing"
)
// TestSurfaceVariesByBiome is the load-bearing correctness check for surface
// rules: it generates real chunks and confirms the top surface block differs
// across biomes. Before surface rules every chunk resolved to grass (9); after,
// deserts/oceans/badlands carry sand/gravel/terracotta-family blocks.
func TestSurfaceVariesByBiome(t *testing.T) {
gen := NewVanillaGenerator(12345)
seen := make(map[uint16]int) // surfaceBlockID → chunk count
// Scan a moderate area to find dry land (surface above sea level), where
// surface rules actually place biome-specific blocks. Ocean columns sit
// below sea level and stay stone, which is correct.
for cx := 0; cx < 16; cx++ {
for cz := 0; cz < 16; cz++ {
ch := gen(int32(cx)-8, int32(cz)-8)
if ch == nil {
continue
}
blk, dry := centreSurfaceBlock(ch)
if !dry {
continue // skip ocean/underwater columns
}
if blk != 0 {
seen[blk]++
}
}
}
if len(seen) < 2 {
t.Fatalf("expected >=2 distinct dry-land surface blocks, got %d (%v)", len(seen), seen)
}
t.Logf("dry-land surface block distribution: %v", seen)
}
// centreSurfaceBlock returns the topmost non-air/non-water block at (8,8) and
// whether that block sits at or above sea level (i.e. it is dry land, where
// surface rules apply rather than being submerged).
func centreSurfaceBlock(ch *Chunk) (uint16, bool) {
for i := SectionCount - 1; i >= 0; i-- {
s := ch.sections[i]
if s == nil {
continue
}
for ly := 15; ly >= 0; ly-- {
st := s[blockIndex(8, MinY+i*16+ly, 8)]
if st != StateAir && st != StateWater {
// Dry only if this top block is at/above sea level.
return st, (MinY+i*16+ly) >= SeaLevel
}
}
}
return 0, false
}