public void setLightValue(int x, int y, float v)
    {
        if(v<0f || x < 0 || x >= blocks.length || y < 0 || y >= blocks[0].length)
            return;
        if(chunkID < 0)
            x = 15-x;
        lightValues[x][y] = v;
        this.lightChanges[x][y] = (int)lvl.ticks;
    }