Now that you know what the changes are and have set up Gradle it is time to set up Forge.
Obviously you have to download a new version of Forge, but you can’t go for the recommended version. That is the last version that is still without Gradle. Instead you should get the newest version of Forge from the File Server over here. Make sure you get the src version. Once you have downloaded the file you should extract it somewhere just like you used to. This will be the folder that contains Forge, but also all of your code.
The next step is going to be a bit harder. Since there no longer is an install file you will have to do something a bit different. Open up the command prompt at the forge folder by on windows Shift clicking on the forge folder and selecting Open command window here. Now write the following command.
This will start a progress that will set up everything you need to start coding for Minecraft 1.6.4.
The next thing you have to do is create a new folder. The folder can have any name and it’s where you will point Eclipse to. Once you have made the folder open Eclipse and set it to that folder. You will likely have a window that doesn’t contain any code. Go to the workspace by hitting the button on the top right. After that you will have to go the top left and select File and then Import… Next open up the General folder at the top and finally Existing Projects into Workspace. This will open up a new window in which you should click the Browse button. Then browse to the forge folder and select that and then hit finish.
You should get a new project with a name that is the same as your forge folder. In that folder should be 2 more folders which contain an example mod. There are also a lot of libraries and a few other files you don’t have to worry about.
The next thing you will have to do is create a Java application to run it. To do this click on the downward arrow just right of the green run button. Then go to Java Application on the left and right click that. Then select New.
Now set the name to something like: Run Client
Then for the Project select the Forge project which is in my case: forge-1.6.4-220.127.116.114-src
Next set the Main class to: net.minecraft.launchwrapper.Launch
Then you should navigate to the Arguments tab. In there are 2 things you should add. First the Program Arguments: –version 1.6 –tweakClass cpw.mods.fml.common.launcher.FMLTweaker
And finally the VM arguments: -Dfml.ignoreInvalidMinecraftCertificates=true
If you just copy all of these straight from this page and paste them in there you should have a working Minecraft Client for you to play with your own mods.
To get to the Minecraft source code you can open the forge library which should be at the bottom of the library list. You can’t edit any of the code in there, but you can look through it to learn why and how something works in Minecraft.