GML floor vs div

[xDGameStudios]

Hi everyone I have a question, even though floor and div return the same result...

x div y == floor(x / y);

Is there any good reason to use one instead of another and performance wise what would be the best option?!

 

[slojanko]

There is a slight difference in favor of div: 100.000.000 operations took roughly 25.1s for divide&floor and 24.5s for div. I don't have YYC at the moment but you might see different results on that.

 

[Simon Gust]

There is a slight difference in favor of div: 100.000.000 operations took roughly 25.1s for divide&floor and 24.5s for div. I don't have YYC at the moment but you might see different results on that.

YYC gives me a difference of about 50% (div being faster).

 

[xDGameStudios]

Thank you very much

 

[TimothyAllen]

do they return the same result on a negative? I would assume these results:

-3 div 2 = -1
floor(-3 / 2) = -2

But I could be wrong.

 

[Simon Gust]

do they return the same result on a negative? I would assume these results:

-3 div 2 = -1
floor(-3 / 2) = -2

But I could be wrong.

They do return different values.
-3 div 2 returns -1
and
floor(-3 / 2) returns -2

 

[meseta]

floor rounds towards negative infinity; div rounds towards zero.

You'd want to use floor for things that need to behave consistently across zero (like tile movement, and rounding position to the nearest multiple of the tile - if you used div for this, you'd find weird behaviour as everything just left of zero rounds up to zero instead of down to -1)

You'd want to use div for things like rounding speed/acceleration, which need to be symmetrical about zero; if you used floor for this, you'd find motion biased to the negative side.

 

[xDGameStudios]

Well I'm using it to draw gui stuff... so coordinates will always be positive... I guess I'll be okay using div then.