I'm working on making a structure but it keeps generating at the world height and not at the ground level, I have tried a lot of times but they just don't generate right.

 

package com.moreoresmod.main.worldgeneration.structure;

import java.util.List;
import java.util.Random;

import com.google.common.collect.Lists;
import com.moreoresmod.main.entitys.EntityDungonProtector;
import com.moreoresmod.main.init.MoreOresModBiomes;
import com.moreoresmod.main.init.MoreOresModBlocks;
import com.moreoresmod.main.init.MoreOresModItems;

import net.minecraft.block.BlockChest;
import net.minecraft.init.Blocks;
import net.minecraft.init.Items;
import net.minecraft.item.ItemStack;
import net.minecraft.tileentity.TileEntity;
import net.minecraft.tileentity.TileEntityChest;
import net.minecraft.tileentity.TileEntityMobSpawner;
import net.minecraft.util.BlockPos;
import net.minecraft.util.WeightedRandomChestContent;
import net.minecraft.world.World;
import net.minecraft.world.biome.BiomeGenBase;
import net.minecraft.world.chunk.IChunkProvider;
import net.minecraftforge.common.ChestGenHooks;
import net.minecraftforge.fml.common.IWorldGenerator;

public class Structures implements IWorldGenerator {

@Override
public void generate(Random random, int chunkX, int chunkZ, World world, IChunkProvider chunkGenerator, IChunkProvider chunkProvider) {
	if(world.provider.getDimensionId() == 0){
		if(world.getBiomeGenForCoords(new BlockPos(chunkX*16, 64, chunkZ*16)).equals(MoreOresModBiomes.otherlyworldBiome)){
			//generateTeleporterStructure(random,chunkX,chunkZ,world);
		}
	}else if(world.provider.getDimensionId() == 2){
		generateOtherlyworldDungen(random, chunkX, chunkZ, world);
	}


}

private void generateTeleporterStructure(Random random, int chunkX, int chunkZ, World world){
	int startX = chunkX * 16 + random.nextInt(16);
	int startY = world.getActualHeight() - 256 + random.nextInt(50);
	int startZ = chunkZ * 16 + random.nextInt(16);
	BlockPos pos = new BlockPos(startX,startY,startZ);
	world.setBlockState(pos, Blocks.bedrock.getDefaultState());
	int width = random.nextInt(5) *2 + 10;
	int length = width*2;
	int height = 7;
	for (int x=0; x<width; x++) {
		for (int z=0; z<length; z++) {
			for (int y=0; y<height; y++) {
				BlockPos bpos = pos.add(x, y, z);
				if (x==0 || x==width-1 || y==0 || y== height-1 || z==0 || z== length-1) 
					world.setBlockState(bpos, Blocks.bedrock.getDefaultState());
				else world.setBlockState(bpos, Blocks.air.getDefaultState());
			}
		}
	}
	int doorX = width /2;
	int chestZ = length-2;

	//door
	world.setBlockState(pos.add(doorX-1,1,0), Blocks.air.getDefaultState());
	world.setBlockState(pos.add(doorX-1,2,0), Blocks.air.getDefaultState());
	world.setBlockState(pos.add(doorX,1,0), Blocks.air.getDefaultState());
	world.setBlockState(pos.add(doorX,2,0), Blocks.air.getDefaultState());

	//chest
	world.setBlockState(pos.add(doorX, 1, chestZ), Blocks.chest.getDefaultState());
	world.setBlockState(pos.add(doorX-1, 1, chestZ), Blocks.chest.getDefaultState());

}

private void generateOtherlyworldDungen(Random rand, int chunkX, int chunkZ,World world){
	int startX = chunkX * 16 + rand.nextInt(50);
	int startY = world.getActualHeight() - 1;
	int startZ = chunkZ * 16 + rand.nextInt(50);



	while(world.getBlockState(new BlockPos(startX,startY,startZ)) == Blocks.air){
		startY--;
	}

	if(world.getBlockState(new BlockPos(startX,startY,startZ)) != Blocks.air){

		BlockPos pos = new BlockPos(startX, startY, startZ);

		for(int x = pos.getX() - 5; x == pos.getX() + 5; x++){
			for(int z = pos.getZ() - 5; z == pos.getX() + 5; z++){
				int y = pos.getY();

				world.setBlockState(new BlockPos(x, y, z), MoreOresModBlocks.otherlyworld_brick.getDefaultState());

			}
		}

		BlockPos spawner1 = pos.add(-3, 0, -3);

		 world.setBlockState(spawner1, Blocks.mob_spawner.getDefaultState(), 2);
             TileEntity tileentity1 = world.getTileEntity(spawner1);

             if (tileentity1 instanceof TileEntityMobSpawner)
             {
                  ((TileEntityMobSpawner)tileentity1).getSpawnerBaseLogic().setEntityName("Darkness");
             }
             
             BlockPos spawner2 = pos.add(3, 0, -3);

		 world.setBlockState(spawner2, Blocks.mob_spawner.getDefaultState(), 2);
             TileEntity tileentity2 = world.getTileEntity(spawner2);

             if (tileentity2 instanceof TileEntityMobSpawner)
             {
                  ((TileEntityMobSpawner)tileentity2).getSpawnerBaseLogic().setEntityName("Darkness");
             }
             
             BlockPos spawner3 = pos.add(-3, 0, 3);
  			
		 world.setBlockState(spawner3, Blocks.mob_spawner.getDefaultState(), 2);
             TileEntity tileentity3 = world.getTileEntity(spawner3);

             if (tileentity3 instanceof TileEntityMobSpawner)
             {
                  ((TileEntityMobSpawner)tileentity3).getSpawnerBaseLogic().setEntityName("Darkness");
             }

             BlockPos spawner4 = pos.add(3, 0, 3);
   			
		 world.setBlockState(spawner4, Blocks.mob_spawner.getDefaultState(), 2);
             TileEntity tileentity4 = world.getTileEntity(spawner4);

             if (tileentity4 instanceof TileEntityMobSpawner)
             {
                  ((TileEntityMobSpawner)tileentity4).getSpawnerBaseLogic().setEntityName("Darkness");
             }
             
	}

}

}

[\code]

Well your generateOtherlyworldDungen method uses:

int startY = world.getActualHeight() - 1;

Why don't you use World#getHeightValue(x, z)? That will give you the actual ground level for those coordinates.

It appears in 1.8.8 forge they removed world.getHeightValue Is there another way?

It appears in 1.8.8 forge they removed world.getHeightValue Is there another way?

 

The method you want is

World#getHeight(BlockPos)

in 1.8+.