Sakura island blender render

Sakura Island is the spawn point in my minecraft server. Of course it would not be possible to place sakura trees in game, so what’s actually in Minecraft is pink wool. Nevertheless they still look nice from far away.

I tried water caustics with refraction and fresnel effects, which make water more realistic at the cost of increased samples and render time. Also I attempted a manual material override on tree leaves, However that seems worth it.

This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Minecraft creation by me, exported with mineways on wine, rendered on blender with cuda. As usual, full resolution of 4096×4096 is available on pixiv.

Sakura Island At Night
Rendered in Blender

[Errata] Windows upgrade to 1703 broke grub

What happened?

After windows upgrading itself to release 1703 aka. the creator update, Grub bootloader can no longer start and says error: unknown filesystem and dropped in to grub rescue shell. Windows boots up fine from firmware memu.

TL; DR

Manually doing hexediting just taught me another valuable lesson: @Windows has the worst upgrade handling.

— @cth451 July 28, 2017

  1. Prepare a USB linux live environment.
  2. Find the correct partition number, it might have been changed during upgrade.
  3. Look for grubx64.efi in your EFI system partition and use a hex editor to open it
  4. Search for /boot/grub and notice the (,gptN) where N is your original partition number for linux OS.
  5. Change N to the new parition number, save the file and reboot.

Analysis

Before upgrade, my partition scheme was:

  • sda1 fat32: EFI system parition
  • sda2 ext4: Archlinux root filesystem
  • sda4 ntfs: Windows drive C
  • sda3 ext4: AOSC OS root filesystem

Partition numbers were not exactly in physical order of data, for I shrinked Archlinux to make room for Windows installation. However after upgrade, it became:

  • sda1 fat32: EFI system parition
  • sda2 ext4: Archlinux root filesystem
  • sda3: Windows drive C
  • sda4: Windows recovery environment
  • sda5: AOSC OS root filesystem

So what did windows do down there? It shrinked drive C and made a little recovery partition, then re-sorted the partition numbers. However grub bootloader looks for partitions by partition number. It tried parition 3 (which was a valid linux filesystem), but it’s an ntfs now.

This partition number is hardcoded into the bootloader efi image, so we need to manually hexedit it.

Triangle Garden (Blender Rendering Teaser)

New features I discovered in blender: manual (and sophiscated) water surface reflection controls! I tried some techiques from the computer graphics class I’m taking this semester, and the result is over fancy. I forgot to ask blender to keep rendering specs. The only specs I remembered are 4096 samples per pixels and that I started blender before I went to sleep, and the process actually had finished before I woke up the next day for classes.

Anyways, here’s the pic. As usual, the image here is downscaled so that the page loads in acceptable time. Shoot me an email for the full image at 4320×2160 if you have 4K (?) displays. See Minecraft Server Page to join the server where I built this thing.

Triangle Garden Rev2 2:1 2160x1080
Triangle Garden Rev2 2:1 2160×1080

Minecraft 1.8 Forge API IBlockState 与渲染

在 Minecraft 内部,方块也可以看作是可放置的物品,使用 Item 类的静态方法 getItemFromBlock(Block someBlock) 可以获得对应的物品。向游戏内注册该方块也是类似的使用 GameRegistry.registerBlock(Block blockToReg, String unlocalizedName)。然而在处理渲染时需要多额外的一步。

以下为 Item 渲染

String nameToReg = MOD_ID + ':' + item.getUnlocalizedName().substring(5);
Minecraft.getMinecraft()
        .getRenderItem().getItemModelMesher()
        .register(item, 0,
        new ModelResourceLocation(nameToReg, "inventory");

以下为 Block 渲染

Item item = Item.getItemFromBlock(block);
// 从 Block 得到对应的 Item
String nameToReg = MOD_ID + ':' + item.getUnlocalizedName().substring(5);
Minecraft.getMinecraft()
        .getRenderItem().getItemModelMesher()
        .register(item, 0,
        new ModelResourceLocation(nameToReg, "inventory");

区别主要在于多了一句从 Block 获得 Item。虽然是以 Item 注册了渲染,实际上这里和 Item 处理渲染的方法并不相同。

assets/<MOD_ID>/blockstates/<blockUnlocalizedName>.json

我所写的 mod 中许多方块都会根据不同的 BlockState 改变渲染模型,而 BlockState 中不同 IProperty 组合所对应状态所对应的模型在这里指定。关于 BlockState,见上一篇 Forge API 详解。我在这里以 TransitRailMod 的电缆架作为例子。

在源代码中,WirePanel 是 CustomDirectionalBlock 的子类,因此继承其 EnumFacing FACING 的属性,这个方块又根据电缆架上是否插了日光灯改变 EnumBool LAMP 属性、是否是封闭的改变 EnumBool SHUT 属性。因此罗列一下: Continue reading Minecraft 1.8 Forge API IBlockState 与渲染

Minecraft 1.8 Forge API BlockState 与红石详解

由于网上找到的 Minecraft Forge 文档实在是少的可怜,我决定自己写一份以防未来的自己忘记。具体的实践可以在我的客运铁路 mod 见到。

红石的更新本质上也是方块更新,因此当一个方块想要检测红石信号,处理的代码应当放在 Block 类的 onNeighborBlockChange(World worldIn, BlockPos pos, IBlockState state, Block neighborBlock) 方法。

BlockStateIBlockState

可以在方块的 Class 建立 BlockState 以允许方块拥有不同的状态 (IProperty),不同的状态可以在 assets/<MODID>/blockstates/<block_instance_name>.json 中定义不同的方块模型。

每一个 IProperty 拥有自己的 name 和可以取到的有限个值,这些值在 Java 内部以 enum 的形式实现。关于 enum 变量类型,可以在王八壳的 javadoc 上找到。

一个方块的 BlockState 可以包含一个或多个 IProperty,可以使用已经定义好的 IProperty 子类(PropertyDirection, PropertyBool)也可以自己定义 enum 建立 PropertyEnum

Class: public CustomBlock extends Block

通过以下方式建立 IProperty 及其子类的实例:

  • public static final PropertyDirection FACING = PropertyDirection.create("facing", EnumFacing.Plane.HORIZONTAL);
    建立新的方向属性,名称为 "facing" ,可以取的值为平面方向的朝向,为 EnumFacing 下的 NORTHEASTSOUTHWEST
  • public static final PropertyBool POWERED = PropertyBool.create("powered");
    建立布尔型只能为 truefalse 的方块属性。

Continue reading Minecraft 1.8 Forge API BlockState 与红石详解

EarthLiveShell 在桌面从太空看地球

之前在 GitHub 上看到 bitdust 用 C# 做的一个能够获取卫星影像并设定为壁纸的程序 EarthLiveSharp (v2ex 讨论),可惜只能在 Windows 下工作。趁着会考完结花几天时间用 Bash 实现了一个能够在 Linux Gnome 下工作的版本

setsid <command> & 可以使进程直接挂在 init 下面作为新的 session 运行,EarthLiveShell 的服务进程即使用这种方法保持在后台。

附上截图

EarthLive

Time-based One Time Password Algorithm

Follow the algorithm

As implemented in Google Authenticator app, you’ll need:

  • A shared secret key K, which is base32 encoded
  • a specific time period since UNIX epoch T

I’ll use K = GEZDGNBVGY3TQOJQGEZDGNBVGY3TQOJQ and T = 1450235092 (which is Wed, 16 Dec 2015 11:04:52 CST) for example. In the Google Authenticator App, both K and T are passed to TOTP as hexadecimal values (or byte arrays).

Since K is a base32 encoded string, we’ll decode it to byte format. Password changes every 30 seconds, T should be divided by 30, tuncated to integer and converted to hex and padded to 16 hexadecimal digits.

Continue reading Time-based One Time Password Algorithm

Systemd Timers小结

分析

Linux上的守护进程cron能够根据配置好的crontab定时地执行某一个动作,现在用上systemd了想要找一个替代品,于是找到了timertimer和其他的配置单元结构差不多,只是有一个[Timer]段,在这里可以定义它的行为。基本的写法是Name=Value。

作为一个timer必须要有

[Install]
WantedBy=timers.target

[Unit] Description=Value

这个字段允许添加对配置单元的描述

[Timer] Unit=Value

用于指定该timer触发时要启动的配置单元,如果不写的话,example.timer触发时会执行同名的example.service

[Timer] 绝对触发时间

OnCalendar=Value可以指定在系统时钟的某一特定时刻触发timer。懒的话可以直接使用hourlymonthly这样的词语,也可以输入DAY YYYY-MM-DD HH:MM:SS。比如hourly*:00:00等价,Wed *:00:00就是每个星期三隔一个小时触发一次。 Continue reading Systemd Timers小结