LightLevelMod.java

package com.cab404.moblightlevel;

import net.minecraft.client.Minecraft;
import net.minecraft.client.entity.EntityPlayerSP;
import net.minecraft.client.renderer.GlStateManager;
import net.minecraft.util.math.BlockPos;
import net.minecraft.world.EnumSkyBlock;
import net.minecraft.world.World;
import net.minecraftforge.client.event.RenderWorldLastEvent;
import net.minecraftforge.common.MinecraftForge;
import net.minecraftforge.event.world.BlockEvent;
import net.minecraftforge.fml.common.Mod;
import net.minecraftforge.fml.common.Mod.EventHandler;
import net.minecraftforge.fml.common.event.FMLInitializationEvent;
import net.minecraftforge.fml.common.eventhandler.SubscribeEvent;
import net.minecraftforge.fml.common.gameevent.TickEvent;
import org.lwjgl.opengl.GL11;

import java.util.ArrayList;
import java.util.List;

@Mod(
        modid = LightLevelMod.MODID,
        version = LightLevelMod.VERSION,
        clientSideOnly = true,
        canBeDeactivated = true
)
public class LightLevelMod {
    public static final String MODID = "com.cab404.moblightlevelmod";
    public static final String VERSION = "1.0";

    int glCross = -1;

    List<BlockPos> spawnPoints;

    boolean disabled = false;

    @EventHandler
    public void init(FMLInitializationEvent event) {
        disabled = false;
        MinecraftForge.EVENT_BUS.register(this);
    }

    BlockPos.MutableBlockPos tmp = new BlockPos.MutableBlockPos();
    BlockPos.MutableBlockPos last = new BlockPos.MutableBlockPos();

    @SubscribeEvent
    public void render(RenderWorldLastEvent ev) {
        if (disabled) return;
        if (spawnPoints == null) return;

        EntityPlayerSP player = Minecraft.getMinecraft().player;
        float refx = (float) (player.lastTickPosX + (player.posX - player.lastTickPosX) * ev.getPartialTicks());
        float refy = (float) (player.lastTickPosY + (player.posY - player.lastTickPosY) * ev.getPartialTicks());
        float refz = (float) (player.lastTickPosZ + (player.posZ - player.lastTickPosZ) * ev.getPartialTicks());

        if (glCross == -1) {
            glCross = GL11.glGenLists(1);
            GlStateManager.glNewList(glCross, GL11.GL_COMPILE);
            GlStateManager.glBegin(GL11.GL_QUADS);
            GlStateManager.glVertex3f(0.3f, .1f, 0.3f);
            GlStateManager.glVertex3f(0.3f, .1f, 0.7f);
            GlStateManager.glVertex3f(0.7f, .1f, 0.7f);
            GlStateManager.glVertex3f(0.7f, .1f, 0.3f);
            GlStateManager.glEnd();
            GlStateManager.glEndList();
        }

        GlStateManager.pushMatrix();
        GlStateManager.enableBlend();
        GlStateManager.blendFunc(GL11.GL_SRC_ALPHA, GL11.GL_ONE_MINUS_SRC_ALPHA);
        GlStateManager.enableDepth();
        GlStateManager.depthMask(true);
        GlStateManager.glLineWidth(2.0f);
        GL11.glEnable(GL11.GL_LINE_SMOOTH);

        GlStateManager.translate(-refx, -refy, -refz);

        GlStateManager.color(1, 0, 0, 0.7f);
        for (BlockPos pos : spawnPoints) {
            GlStateManager.translate(pos.getX(), pos.getY(), pos.getZ());
            GlStateManager.callList(glCross);
            GlStateManager.translate(-pos.getX(), -pos.getY(), -pos.getZ());
        }

        GlStateManager.translate(refx, refy, refz);

        GlStateManager.glLineWidth(1.0f);
        GL11.glDisable(GL11.GL_LINE_SMOOTH);
        GlStateManager.enableTexture2D();
        GlStateManager.disableBlend();
        GlStateManager.enableTexture2D();

        GlStateManager.popMatrix();
    }

    @SubscribeEvent
    public void show(BlockEvent ev) {
        updateData();
    }

    @SubscribeEvent
    public void show(TickEvent.PlayerTickEvent ev) {
        updateData();
    }

    private void updateData() {
        if (disabled) return;

        Minecraft minecraft = Minecraft.getMinecraft();
        EntityPlayerSP player = minecraft.player;
        if (player == null) return;
        World world = player.getEntityWorld();

        minecraft.mcProfiler.startSection("moblightlevels");
        BlockPos ppos = player.getPosition();

        int px = ppos.getX();
        int py = ppos.getY();
        int pz = ppos.getZ();

        if (last.getX() == px && last.getY() == py && last.getZ() == pz) return;
        last.setPos(ppos);


        ArrayList<BlockPos> positions = new ArrayList<BlockPos>();

        for (int x = -10; x < 10; x++) {
            for (int y = -10; y < 10; y++) {
                for (int z = -10; z < 10; z++) {

                    if (py + y <= 0 || py + y >= world.getActualHeight())
                        continue;

                    tmp.setPos(x + ppos.getX(), y + ppos.getY(), z + ppos.getZ());

                    if (!world.isAirBlock(tmp))
                        continue;

                    if (world.getLightFromNeighborsFor(EnumSkyBlock.BLOCK, tmp) > 7)
                        continue;

                    tmp.setPos(x + px, y + py - 1, z + pz);

                    if (!world.isBlockFullCube(tmp))
                        continue;

                    positions.add(new BlockPos(x + px, y + py, z + pz));
                }
            }
        }
        spawnPoints = positions;

        minecraft.mcProfiler.endSection();
    }

}