I have a couple custom biomes with designated custom surface builders, although I don't know how to make the kind of biome surface builder I want. So what I am asking, is a walkthrough to how the default biome surface builder works, and how I can create my own to the type of biome I want, this is the default biome surface builder:

protected void buildSurface(Random random, IChunk chunkIn, Biome biomeIn, int x, int z, int startHeight, double noise, BlockState defaultBlock, BlockState defaultFluid, BlockState top, BlockState middle, BlockState bottom, int sealevel) {
   BlockState blockstate = top;
   BlockState blockstate1 = middle;
   BlockPos.Mutable blockpos$mutable = new BlockPos.Mutable();
   int i = -1;
   int j = (int)(noise / 3.0D + 3.0D + random.nextDouble() * 0.25D);
   int k = x & 15;
   int l = z & 15;

   for(int i1 = startHeight; i1 >= 0; --i1) {
      blockpos$mutable.setPos(k, i1, l);
      BlockState blockstate2 = chunkIn.getBlockState(blockpos$mutable);
      if (blockstate2.isAir()) {
         i = -1;
      } else if (blockstate2.getBlock() == defaultBlock.getBlock()) {
         if (i == -1) {
            if (j <= 0) {
               blockstate = Blocks.AIR.getDefaultState();
               blockstate1 = defaultBlock;
            } else if (i1 >= sealevel - 4 && i1 <= sealevel + 1) {
               blockstate = top;
               blockstate1 = middle;
            }

            if (i1 < sealevel && (blockstate == null || blockstate.isAir())) {
               if (biomeIn.getTemperature(blockpos$mutable.setPos(x, i1, z)) < 0.15F) {
                  blockstate = Blocks.ICE.getDefaultState();
               } else {
                  blockstate = defaultFluid;
               }

               blockpos$mutable.setPos(k, i1, l);
            }

            i = j;
            if (i1 >= sealevel - 1) {
               chunkIn.setBlockState(blockpos$mutable, blockstate, false);
            } else if (i1 < sealevel - 7 - j) {
               blockstate = Blocks.AIR.getDefaultState();
               blockstate1 = defaultBlock;
               chunkIn.setBlockState(blockpos$mutable, bottom, false);
            } else {
               chunkIn.setBlockState(blockpos$mutable, blockstate1, false);
            }
         } else if (i > 0) {
            --i;
            chunkIn.setBlockState(blockpos$mutable, blockstate1, false);
            if (i == 0 && blockstate1.getBlock() == Blocks.SAND && j > 1) {
               i = random.nextInt(4) + Math.max(0, i1 - 63);
               blockstate1 = blockstate1.getBlock() == Blocks.RED_SAND ? Blocks.RED_SANDSTONE.getDefaultState() : Blocks.SANDSTONE.getDefaultState();
            }
         }
      }
   }

}

So if anyone could walk me through how this works, that would be amazing. Also if someone would tell me the math I would have to do to make a sahara surface builder, that would be awesome.

Well, I see a for loop that starts at a startHeight and if the block at that position is air, it (continues the loop and) goes down.

If the block is the same as defaultBlock, then it does some other stuff to determine what block to place at that position instead. i (but starts at -1, meaning the first block that isn't air does something different than if i > 0--set by j) and j are based on some noise values. i and the seaHeight determine what block is placed.

Edited June 18, 20205 yr by Draco18s