added section on making decisions
This commit is contained in:
walterhiggins
parent
9455a31889
commit
6d7b666b57
1 changed files with 76 additions and 7 deletions
|
|
@ -1,8 +1,6 @@
|
|||
# The Young Person's Guide to Programming in Minecraft
|
||||
## 2013/01/08 17:26
|
||||
|
||||
## Draft
|
||||
|
||||
### Introduction
|
||||
|
||||
Minecraft is an open-ended 3D game where you can build and craft
|
||||
|
|
@ -839,12 +837,82 @@ logical step. Of course, Minecraft doesn't have the same constraints
|
|||
as real-world densely populated areas so let your imagination go wild.
|
||||
|
||||
|
||||
TODO
|
||||
### Making Decisions
|
||||
TODO
|
||||
### Making Decisions
|
||||
|
||||
All the programs we have seen so far have been fairly predictable - they went
|
||||
straight through the statements, and then went back to the beginning again. This is
|
||||
not very useful. In practice the computer would be expected to make decisions and
|
||||
act accordingly. The javascript statement used for making decisions is `if`.
|
||||
While standing on the ground in-game, type the following at the command prompt...
|
||||
|
||||
/js if ( self.flying ) { echo("Hey, You are flying!"); }
|
||||
|
||||
... No message should appear on screen. That is - `Hey, You are
|
||||
flying!` should *not* appear on screen. Now double-tap the `space`
|
||||
bar to start flying in-game (tap the space bar twice in rapid
|
||||
succession), then press and hold space to rise above the ground. Now
|
||||
enter the same statement again (If you don't want to type the same
|
||||
statement again, just press `/` then press the `UP` cursor key on your
|
||||
keyboard, the statement you entered previously should reappear.
|
||||
|
||||
/js if ( self.flying ) { echo("Hey, You are flying!"); }
|
||||
|
||||
... this time the following message should have appeared on your screen...
|
||||
|
||||
Hey, You are flying!
|
||||
|
||||
The `if` statement tests to see if something is `true` or `false` and
|
||||
if `true` then the block of code between the curly braces ( `{` and
|
||||
`}` ) is executed - but only if the condition is true. The condition
|
||||
in the above example is `self.flying` which will be `true` if you are
|
||||
currently flying or `false` if you aren't.
|
||||
|
||||
What if you wanted to display a message only if a condition is *not*
|
||||
true ? For example to only display a message if the player is *not*
|
||||
flying...
|
||||
|
||||
/js if ( ! self.flying ) { echo ("You are not flying."); }
|
||||
|
||||
... This code differs in that now there's a `!` (the exclamation mark)
|
||||
before `self.flying`. The `!` symbol negates (returns the opposite of)
|
||||
whatever follows it.
|
||||
|
||||
What if you want to display a message in both cases - whether you're
|
||||
flying or not? This is where the `if - else` construct comes in handy.
|
||||
Open your favorite editor and type the following code into a new file
|
||||
in your js-plugins directory...
|
||||
|
||||
function flightStatus()
|
||||
{
|
||||
if ( self.flying )
|
||||
{
|
||||
echo( "Hey, You are flying!" );
|
||||
}
|
||||
else
|
||||
{
|
||||
echo( "You are not flying." );
|
||||
}
|
||||
}
|
||||
|
||||
... now type `/reload` at the in-game prompt then type `/js
|
||||
flightStatus()` and an appropriate message will appear based on
|
||||
whether or not you're currently flying. Type the `/js flightStatus()`
|
||||
command while on the ground and while flying. The message displayed in
|
||||
each case should be different.
|
||||
|
||||
### Next Steps
|
||||
|
||||
This guide is meant as a gentle introduction to programming and
|
||||
modding Minecraft using the Javascript Programming Language.
|
||||
Javascript is a very powerful and widely-used programming language and
|
||||
there are many more aspects and features. If you want to dive deeper
|
||||
into programming and modding minecraft I recommend reading the source
|
||||
code to some of the existing scriptcraft add-ons, the *chat* module (
|
||||
`js-plugins/chat/chat.js` ) is a good place to start, followed by
|
||||
[Anatomy of a ScriptCraft Plug-in][ap]. The online [Craftbukkit API
|
||||
Reference][cbapi] provides lots of valuable information about the
|
||||
different objects and methods available for use by ScriptCraft.
|
||||
|
||||
#### if then else
|
||||
TODO
|
||||
|
||||
[buk]: http://wiki.bukkit.org/Setting_up_a_server
|
||||
[dlbuk]: http://dl.bukkit.org/
|
||||
|
|
@ -855,6 +923,7 @@ TODO
|
|||
[cbapi]: http://jd.bukkit.org/beta/apidocs/
|
||||
[boole]: http://en.wikipedia.org/wiki/George_Boole
|
||||
[soundapi]: http://jd.bukkit.org/beta/apidocs/org/bukkit/Sound.html
|
||||
[ap]: http://walterhiggins.net/blog/ScriptCraft-1-Month-later
|
||||
|
||||
[img_echo_date]: img/ypgpm_echo_date.png
|
||||
[img_3d_shapes]: img/ypgpm_3dshapes.jpg
|
||||
|
|
|
|||
Reference in a new issue