A stupid bug I wrote...

Miscellaneous Topics
#1

Wrote this code:


			target.set(position).add(direction);
			up.set(0, 1, 0);
			if(direction.x == 0 && direction.y == 0);{
				up.set(0, 0, 1); //Ensure up is not the same direction as "direction"
			}

			System.out.println(up); //Bug: up is always (0, 0, 1).

			viewMatrix.setToLookAt(position, target, up);

Neither direction.x and direction.y were 0, but up was still set to (0, 0, 1). What was the problem?

Answer:
[spoiler]
There’s a semi-colon right after the if()-clause. The code is basically this:

if(…);

{
up.set(0, 0, 1);
}

It’s an if-statement without a body. The curly braces are unrelated to the if-statement and don’t really do anything here.
[/spoiler]

Not sure if that was obvious to everyone else, but it sure took me some debugging to find that… .___.

#2

well: there is an angry face in the code:

;{

always delete the angry faces!

#3

Don’t you just wish you had a debugger in your brain?

#4

This won’t really work. Comparing floating point values with ‘==’ or ‘!=’ should have a very high stink value. LookAt formulations degenerate as the direction approaches linear dependent (so approaching same and approaching opposite).

#5

I’m not sure, but I think there might be possible for Eclipse to teach him, to warn about angry faces. Unless, they are in regular use as well, then it’d be annoying.

#6

The direction is manually set, so it’s very likely to be hardcoded to exactly straight down. I haven’t had any precision problems with it so far, but yeah, might have to add a tolerance area.

#7

IDEs like NetBeans & Eclipse warn about this…

#8

Weird, my Eclipse doesn’t…

#9

You probably have to enable it in some settings

#10

My Eclipse and Netbeans don’t either. I use Netbeans at school and Eclipse at home and never once has either IDE warned me about frowny faces.

#11

There is no such warning for eclipse.
There ought to be D=

Why can I just open curly brackets ? Why is this allowed at all ? =/

#12

IntelliJ warns about it, saved me a couple of times. Don’t know about the rest of you, but even when writing text I tend to end lines with semicolons… :slight_smile:

#13

There is a plugin called “FindBugs” that warns for it (among other potential issues like forgetting to close a stream). :slight_smile:

Mike

#14

That is a funny bug that happens to me as well. I have Eclipse and Intellij, and I don’t get warnings for it either. Gonna start searching for some now :stuck_out_tongue:

Is there really any practical use for [icode]if(true);[/icode] that I’m not aware of? ??? (Maybe it was just in there to troll debugging programmers :smiley: )

#15

My code formatter (which executes every time I save), would have changed:


         if(direction.x == 0 && direction.y == 0);{
            up.set(0, 0, 1); //Ensure up is not the same direction as "direction"
         }

to:


         if(direction.x == 0 && direction.y == 0);
         {
            up.set(0, 0, 1); //Ensure up is not the same direction as "direction"
         }

which would cause the alarm bells to ring immediately :slight_smile:

#16

NetBeans:

#17

The eclipse warning for this will be “Empty flow-control statement”.

Yes: debugging. Otherwise languages that are too strict about potential problems are quite annoying…try turning all all warnings that your IDE’s compiler supports.

#18

Curly brackets start a new scope. I’ve seen only a few times, this kind of scoping is used within a method body. As one would guess, You can live without it.

#19 

public static boolean TRUE  = Math.random() < 1.0;
public static boolean FALSE = Math.random() > 1.0;

if(TRUE) {
   // stuff
}
else {
   // dead code, but no warning ^.^
}

Surprisingly useful, and allows you to make your compiler/ide as strict as possible.

#20

Lol, I read that as “makes your booleans truer”. xD