What

[TheOfficialNano]

Very nice... but how do i use it? i've downloaded the files... where do i start the program?

[YSelfTool]

You first need to build the program to start it.
I've just added a prebuilt MapRend.jar to the repository. It's built with Java 8.

To run the program, you need to open a terminal (Windows, _{if you use Linux you probably know how to open a terminal}) in the folder where you've downloaded the files. To run the program type
java -jar MapRend.jar
and press Return.
It will then show you the help.
First you need to generate a colors.json. For that you get the ressource pack of your choice, create the subfolder ressource and ressource/raw in your folder (where you've downloaded the files) and copy all files from assets/minecraft/textures/blocks/ from the ressource pack the ressource/raw. Then run
java -jar MapRend.jar textures ressource.
Now you can generate the map of your world. For that you need the world you want to map. Copy the world (the whole folder from .minecraft/saves/) to your folder (where you've downloaded the files (I'll just call that one the working folder from now on)).
In my case I created a folder tmp/ in my working folder and copied the world to tmp/New World.
To generate the map run
java -jar MapRend.jar map "tmp/New World" ressource.
Of course you need to replace tmp/New World by the path to your world. The "" are needed, because in this case the world name (New World) contains a whitespace.
The map image has been generated to the folder where your world is (in my case tmp/New World-day.png).

How to improve the above process:

• You do not need to copy the world. You can just reference it where it is. Instead of the tmp/New World above, just use the path to your world in the minecraft saves folder (on Linux it's usually ~/.minecraft/saves/New World, on Windows something like C:\Users\Username\AppData\roaming\.minecraft\saves\New World).
• You can specify the folder, where the map is saved. To put it in the working folder, run
  java -jar MapRend.jar map "tmp/New World" ressource ..
  To put it in your Pictures directory, run
  java -jar MapRend.jar map "tmp/New World" ressource "C:\Users\Username\Pictures\" or similar.
• You can get a night map. Run
  java -jar MapRend.jar map "tmp/New World" ressource . night.
• To set the radius of the mapped area to e.g. 500, run
  java -jar MapRend.jar map "tmp/New World" ressource . day 500.
• If you want a rectangular map of the world instead, run
  java -jar MapRend.jar map "tmp/New World" ressource . day 500 rect.

There are some more options. Be aware that only the options at the far end are optional, not the ones inbetween. (java -jar MapRend.jar map "tmp/New World" ressource . day works, java -jar MapRend.jar map "tmp/New World" ressource . rect not.)

If there are still questions (usually there are), feel free to ask.

[TheOfficialNano]

So i've been messing around with the inputs and im beginning to be certain that i am not doing something wrong here
http://oi62.tinypic.com/6hqka8.jpg

[YSelfTool]

The problem should be, that I compiled the program with version 8 of java (to be exact: With openjdk). Previous versions of java, although compatible, can't run it.
EDIT: I've now compiled the program with Java 7. As long as you have that version installed, it should now run (of course you need to pull the repository/redownload the files).
To find out your installed Java version.

[TheOfficialNano]

i am aware, but i did install java 8 to try again, but still got the same error....
What on earth is openjdk?

[YSelfTool]

OpenJDK is a free implementation of Java.
I forgot to clear the cache, so the last version was not really compiled with Java 7.
Now it runs fine even with Java 6 here.
Could you try running it again?

[TheOfficialNano]

It cant find colors.json.... nor can i tho.

[YSelfTool]

You need to generate that colors.json (sorry, above I wrote textures.json, that was wrong) by copying the files from assets/minecraft/textures/blocks/ into the folder ressource/raw and running
java -jar MapRend.jar textures ressource.

[TheOfficialNano]

correction, it says Cannot open colors.json

[TheOfficialNano]

Sorry i cant respond any longer g2g

[YSelfTool]

Do you run
java -jar MapRend.jar map tmp/world ressource
or just
java -jar MapRend.jar map tmp/world?
The first one is correct, the second one assumes the working folder (called .), not the ressource folder inside the working folder (called ./ressource) is the ressource folder.

[TheOfficialNano]

I do run the first one. it says
"Cannot find stone texture"

[YSelfTool]

Which ressource pack do you use?
Some ressource packs don't replace every texture (usually then the default texture is used) and therefor textures are missing for the mapper.

[TheOfficialNano]

i dont use any texturepacks.

[YSelfTool]

Not for minecraft, but for creating the map.
MapRend needs a ressource pack to get the color of the blocks.

First you need to generate a colors.json. For that you get the ressource pack of your choice, create the subfolder ressource and ressource/raw in your folder (where you've downloaded the files) and copy all files from assets/minecraft/textures/blocks/ from the ressource pack the ressource/raw.

If you want to use the default Minecraft textures, you need to extract them from the minecraft.jar-file.
It's (for Windows) in C:\Users\Username\AppData\roaming\.minecraft\versions\1.8.1\minecraft.jar.
Open it with 7zip or similar programs and copy all files from assets/minecraft/textures/blocks/ to ressource/raw/ in your working folder.

[TheOfficialNano]

Alright! that all works now :) but now i cant find biomes.json

[YSelfTool]

You need to copy biomes.json from your working folder to ressource/, then it should work.
Seems like I should streamline some parts of how to use this program.

[TheOfficialNano]

YES NOW IT SEEMS TO MAKE PROGRESS :D
AND YET ANOTHER PROBLEM
"stopping: Unable to load and draw chunk!"

[TheOfficialNano]

i think its bitching about the height limit being at 255

[YSelfTool]

What does it say before stopping: ...? There should be some stacktrace. Could you send a screenshot of that stacktrace?

[TheOfficialNano]

http://oi59.tinypic.com/281ag4z.jpg

[YSelfTool]

Seems like there are new biomes.

[TheOfficialNano]

the world is in 1.7.2

[YSelfTool]

Correction: The program thinks there should be a biome with ID 255. The biome id is saved per chunk in the world file.

[YSelfTool]

Could you try it with another world and/or send me the world it's not working for?

[TheOfficialNano]

I made a new flatworld.. gonna try it with that

[TheOfficialNano]

Sweet mother of god, its working
http://oi59.tinypic.com/30xbm8y.jpg

[YSelfTool]

I've patched the program, so even for invalid biomes it should now work (by using the color of grass in plains).

[YSelfTool]

And congratulations for getting it to work :)

[TheOfficialNano]

aaah 👍

[jamonholmgren]

For Mac OSX, I've added installation and usage instructions (#2) to the README.md in a pull request.