Quick Start Guide

This guide, rather than walk you through installing a set of example mods (i.e. what the tutorial is aimed at), will go over the key concepts every person should know about how to use Minecrafter & successfully use Minecraft mods.

Understand minecraft.jar

If you are new to Minecraft modding, it’s imperative you understand the contents of minecraft.jar. Minecraft.jar is a archive which can be opened in any archive utility (as it is basically a ZIP renamed to JAR). It contains the content used to make Minecraft work. Generally (for simplicity reasons) the contents are broken up into 2 sections: the code (files that end with *.class) and the images.

Here are the key points from minecraft.jar:

.class files

The majority of the gameplay code is contained in the root of the archive, named as either one or two characters with .class at the end. For most gameplay modifying mods, you’ll be replacing one or more of these files.

META-INF folder

The notorious META-INF folder you may have heard of. It is one of the major causes of the dreaded “black screen” which plagues Minecraft uses. It is because this folder contains a digital signature to verify the contents of the class files in the JAR. Because of this, any modification to any class file will cause an exception. So by deleting this folder (or specifically MOJANG_C.DSA and MOJANG_C.SF) you disable the file verification, and thus being able to play with mods.

Image files

The core images are terrain.png (containing the images of the blocks) and gui/items.png (containing the images of the items displayed in the GUI). There are various other graphics that you should look through if you are interested in modifying other elements.

Be aware of a mod’s file structure

It may not seem important when replacing files in minecraft.jar manually, but when loading files in Minecrafter, you have to be clear that files are replacing files in minecraft.jar. For example, Minecart Mania SSP (as of v1.2.6) replaces files such as c.class, lb.class and qd.class.

As you can see, although the files are present and well, the folders “Minecart Mania v2.1h” and “Single Player Version” are preventing the .class files from replacing the exact files in minecraft.jar.

as you can see here in minecraft.jar, the c.class file is green, meaning it’s active. If the file in Minecart Mania was properly replacing c.class, it would be red (indicating it’s inactive). This leads us to our next concept you should be familiar with.

Base Folder

A base folder is simply the folder where the contents “start”. If your mod has class files, the base folder should be the folder containing the class files. To select a base folder, select the mod, and click the base folder button on the bottom right of the form.

Using the example from the previous section, Minecart Mania’s SP mod starts at the folder “Minecart Mania v2.1h/Single Player”. Selecting this folder will trim the file names in the mod package editor form like so:

As you can see in the image, not only is the folder been selected, but files not contained in the base folder are hidden as well. You can switch base folders freely without worry as the whole mod archive is kept in the mod package.

And as you can see, the c.class file in minecraft.jar is red, meaning Minecart Mania’s file is replacing it.

Understand Priority

You’ve already been given a quick example of how priority plays a key role in making a mod package. Priority is the concept of a mod replacing another mod’s files based on the position of the mod in the mods list box. In the previous example, we have Minecart Mania above Minecraft.jar. A mod will always have higher priority than another mod below it.

In our fairly trivial example, having one mod means that we don’t really need to worry about priority. But for people who have the love of mods, would probably have a lot more than one mod loaded in a mod package.

As we can see in this example mod package (a somewhat outdated one), we have a bunch of mods and texture packs, with Frenden’s texture pack taking priority to Nurios.

For more advanced users, you may want to take a look at priority states for making a inactive file “active” to override the default rules. You can read more about it here.


2 Responses to Quick Start Guide

  1. Hekheler says:

    Can this be used to make Texture Packs?

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