trees, but like, weirdly broken

src/level/blockExt.ts

@@ -2,7 +2,13 @@ import type { NoiseFunction2D } from 'simplex-noise'
 import { blockTypes as T, level as L, probability as P } from './def'
 import type { Block } from '../types.d'
 
-function trees(r: number, i: number, row: Block[], previousRow: Block[]) {
+function trees(
+  r: number,
+  i: number,
+  row: Block[],
+  previousRow: Block[],
+  nextRow: Block[],
+) {
   const max = row.length - 1
   const h = i - 1
   const j = i + 1
@@ -10,6 +16,7 @@ function trees(r: number, i: number, row: Block[], previousRow: Block[]) {
   const above = previousRow[i]
   const aboveLeft = previousRow[h]
   const aboveRight = previousRow[j]
+  const below = nextRow[i]
 
   if (current === T.treeCrown) {
     if (i > 0) row[h] = T.treeLeaves
@@ -26,8 +33,8 @@ function trees(r: number, i: number, row: Block[], previousRow: Block[]) {
     if (i < max) row[j] = T.treeLeaves
 
   } else if (above === T.treeTrunk) {
-    if (current === T.air) row[i] = T.treeTrunk
+    if (below === T.soil || below === T.grass) row[i] = T.treeRoot
-    else row[i] = T.treeRoot
+    else row[i] = T.treeTrunk
   } else if (above === T.treeRoot) {
     row[i] = T.soil
     if (i > 0) row[h] = T.treeRoot
@@ -68,9 +75,16 @@ function underground(r: number, i: number, current: Block, above: Block) {
 }
 
 export default function createBlockExtender(rand: NoiseFunction2D) {
-  function growTrees(level: number, column: number, offset: number, row: Block[], previousRow: Block[]) {
+  function growTrees(
+    level: number,
+    column: number,
+    offset: number,
+    row: Block[],
+    previousRow: Block[],
+    nextRow: Block[],
+  ) {
     const r = rand(level, column + offset)
-    trees(r, column, row, previousRow)
+    trees(r, column, row, previousRow, nextRow)
   }
 
   function extendBlock(level: number, column: number, offset: number, current: Block, above: Block) {
@@ -81,10 +95,16 @@ export default function createBlockExtender(rand: NoiseFunction2D) {
     return underground(r, column, current, above)
   }
 
-  function extendRow(level: number, columnOffset: number, row: Block[], previousRow: Block[]) {
+  function extendRow(
+    level: number,
+    columnOffset: number,
+    row: Block[],
+    previousRow: Block[],
+    nextRow: Block[],
+  ) {
     for (let column = 0; column < row.length; column++) {
       if (level < L.ground) {
-        // growTrees(level, column, columnOffset, row, previousRow)
+        growTrees(level, column, columnOffset, row, previousRow, nextRow)
       } else {
         row[column] = extendBlock(level, column, columnOffset, row[column], previousRow[column])
       }

src/level/def.ts

@@ -49,7 +49,7 @@ export const level = {
 }
 
 export const probability = {
-  tree: 0.3,
+  tree: 0.2,
   soilHole: 0.3,
   soilGravel: 0.2,
   stoneGravel: 0.1,

src/level/index.ts

@@ -75,9 +75,10 @@ export default function createLevel(width: number, height: number, seed = 'extre
       const level = levelOffset + i
       const row: Block[] = Array(width)
       const previousRow = i ? _grid[i-1] : [] as Block[]
+      const nextRow = _grid[i+1] ?? [] as Block[]
 
       blockGen.fillRow(level, columnOffset, row)
-      blockExt.extendRow(level, columnOffset, row, previousRow)
+      blockExt.extendRow(level, columnOffset, row, previousRow, nextRow)
 
       _grid[i] = row
     }