SkyLightCubeDiffuseCalculator.java

/*
 *  This file is part of Cubic Chunks Mod, licensed under the MIT License (MIT).
 *
 *  Copyright (c) 2015 contributors
 *
 *  Permission is hereby granted, free of charge, to any person obtaining a copy
 *  of this software and associated documentation files (the "Software"), to deal
 *  in the Software without restriction, including without limitation the rights
 *  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 *  copies of the Software, and to permit persons to whom the Software is
 *  furnished to do so, subject to the following conditions:
 *
 *  The above copyright notice and this permission notice shall be included in
 *  all copies or substantial portions of the Software.
 *
 *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 *  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 *  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 *  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 *  THE SOFTWARE.
 */
package cubicchunks.lighting;

import net.minecraft.util.math.BlockPos;
import net.minecraft.world.EnumSkyBlock;
import net.minecraft.world.World;

import cubicchunks.util.Coords;
import cubicchunks.world.column.BlankColumn;
import cubicchunks.world.column.Column;

class SkyLightCubeDiffuseCalculator {

	//world.checkLightFor needs 17 but we also update neighbor blocks - so it needs to be 18
	private static final int LOADED_BLOCKS_MIN_RADIUS = 18;

	private SkyLightCubeDiffuseCalculator() {
		throw new RuntimeException();
	}

	static boolean calculate(Column column, int localX, int localZ, int cubeY) {
		return calculate(column, localX, localZ, cubeY, 0, 15);
	}

	static boolean calculate(Column column, int localX, int localZ, int cubeY, int minYLocal, int maxYLocal) {
		if (column instanceof BlankColumn || column.getLoadedCube(cubeY) == null) {
			return true;
		}
		// update this block and its xz neighbors
		int blockX = Coords.localToBlock(column.xPosition, localX);
		int minY = Coords.localToBlock(cubeY, minYLocal);
		int maxY = Coords.localToBlock(cubeY, maxYLocal);
		int blockZ = Coords.localToBlock(column.zPosition, localZ);

		World world = column.getWorld();

		//check at min cube Y and max cube Y
		if (!world.isAreaLoaded(new BlockPos(blockX, minY, blockZ), LOADED_BLOCKS_MIN_RADIUS, false)) {
			return false;
		}
		if (!world.isAreaLoaded(new BlockPos(blockX, maxY, blockZ), LOADED_BLOCKS_MIN_RADIUS, false)) {
			return false;
		}

		diffuseSkyLightForBlockColumn(world, blockX, blockZ, minY, maxY);
		diffuseSkyLightForBlockColumn(world, blockX - 1, blockZ, minY, maxY);
		diffuseSkyLightForBlockColumn(world, blockX + 1, blockZ, minY, maxY);
		diffuseSkyLightForBlockColumn(world, blockX, blockZ - 1, minY, maxY);
		diffuseSkyLightForBlockColumn(world, blockX, blockZ + 1, minY, maxY);

		column.setModified(true);
		return true;
	}

	private static void diffuseSkyLightForBlockColumn(World world, int blockX, int blockZ, int minY, int maxY) {
		final BlockPos.MutableBlockPos pos = new BlockPos.MutableBlockPos();
		for (int y = minY; y <= maxY; y++) {
			pos.setPos(blockX, y, blockZ);
			world.checkLightFor(EnumSkyBlock.SKY, pos);
		}
	}
}