Place biome-driven water and lava springs

internal/world/springs_test.go

@@ -0,0 +1,39 @@
+package world
+
+import (
+	"testing"
+
+	"regionio/internal/worldgen"
+)
+
+func TestSpringFeaturePlacesFallingFluid(t *testing.T) {
+	chunk := NewChunk(0, 0, BiomePlains)
+	valid := []string{"minecraft:stone"}
+	for _, pos := range [][3]int{{8, 11, 8}, {8, 9, 8}, {7, 10, 8}, {9, 10, 8}, {8, 10, 7}} {
+		chunk.setBlockRaw(pos[0], pos[1], pos[2], StateStone)
+	}
+	config := worldgen.SpringFeatureConfig{
+		HoleCount: 1, RequiresBlockBelow: true, RockCount: 4,
+		State:       worldgen.BlockState{Name: "minecraft:water", Properties: map[string]string{"falling": "true"}},
+		ValidBlocks: valid,
+	}
+	placeSpring(chunk, 8, 10, 8, config)
+	falling, ok := nameToStateID("minecraft:water", map[string]string{"level": "8"})
+	if !ok || chunk.GetBlock(8, 10, 8) != falling {
+		t.Fatalf("spring state = %d, want falling water %d", chunk.GetBlock(8, 10, 8), falling)
+	}
+}
+
+func TestPlacedSpringsAreDeterministic(t *testing.T) {
+	gen := NewVanillaGenerator(12345)
+	a, b := gen(-3, 4), gen(-3, 4)
+	for y := MinY; y < MinY+WorldHeight; y++ {
+		for x := 0; x < 16; x++ {
+			for z := 0; z < 16; z++ {
+				if got, want := a.GetBlock(x, y, z), b.GetBlock(x, y, z); got != want {
+					t.Fatalf("block (%d,%d,%d): first %d second %d", x, y, z, got, want)
+				}
+			}
+		}
+	}
+}