testing equality of two quaternions?

hebdemnobad · 19-Dec-2013 18:52:47

is there a function for comparing two quaternions.....I want to know if two rotation values are equal to one another. Do I have to break each quaternion into four floats to do the test, or is there a simpler way?

-thx

arkeon · 19-Dec-2013 20:36:36

hmm no there is not ^^
you're right this should be usefull, you can add a ticket on redmine for this

for now you can compare each values

iri · 19-Dec-2013 21:03:32

// return 1 if equal otherwise 0
fun check (q1, q2)=
	let q1 -> [a1 b1 c1 d1] in
	let q2 -> [a2 b2 c2 d2] in
	if a1 != a2 then
		0
	else if b1 != b2 then
		0
	else if c1 != c2 then
		0
	else if d1 != d2 then
		0
	else
		1;;

iri · 19-Dec-2013 21:06:30

Arkeon : dan is right, quaternions are a bad performance. A table would be better and faster, what do you think, on the long time ?

hebdemnobad · 19-Dec-2013 21:25:01

Thx guys

arkeon · 19-Dec-2013 22:05:33

Actually I think that is quite the same performance in the VM.
the model have been taken from the zooengine and it's euler rotations

iri · 20-Dec-2013 00:17:13

Not in the VM, but in Scol (a pkg if you want), a tuple manipulation is slower than a table manipulation. This is why I say that.

arkeon · 20-Dec-2013 14:10:26

ha ok you mean to type the code not the execution time

maybe that we could add a new tuple syntax, something like "tuple[pos]" to get a value

iri · 20-Dec-2013 14:26:47

arkeon wrote:

ha ok you mean to type the code not the execution time
maybe that we could add a new tuple syntax, something like "tuple[pos]" to get a value

a tuple such as [a b c d]

For some operation, it need to do
let tuple -> [a b c d] in
// operations only on d, by example

With a table :
// operation on tab.3, directly and easily. In this case, one statment instead two.

Other thing, with a table, it is easy to do a recursion or perform a WHILE. It is difficult with a tuple. To do, not to write with a keyboard.
So, yes, i mean to the execution time. That is why I wonder whether it is not better to replace tuple by table generally (not only on these quaternons).

Otherwise, i had done this, in Syspack : http://www.scolring.org/files/doc_html/ … tuple.html

arkeon · 20-Dec-2013 15:12:02

It can be useful for recursion but tuple with different types won't make this use possible.
since lists are tuples with the same types in this case the developer should use lists.

I still don't see where it can be faster in execution time since tabs and tuples are the same in the VM.

iri · 20-Dec-2013 16:05:55

Of course, when this replacement is possible (same type) ....

When you manipulate a tuple, you shpuld often do
a let tuple -> [ ...] in
even if you've only need the third element.
when a table, you create it once time, that's all.
Aloop /recursion can be faster, else equal.

For ONE statment, i'm ok, the performance is the same and the access time is the same. I'm not sure that they are equals in an application such as os3d.

arkeon · 20-Dec-2013 16:41:35

you can also do

let tuple -> [_ _ elem _] in

iri · 20-Dec-2013 21:12:18

euh yes, i know ! thanks !!

let tuple -> [_ _ elem _] in // +1 locale variable
myFunction elem; // 2 statments

myFunction table.2; // 1 statment, 0 locale variable

Scolring - Forum

#1 19-Dec-2013 18:52:47

testing equality of two quaternions?

#2 19-Dec-2013 20:36:36

Re: testing equality of two quaternions?

#3 19-Dec-2013 21:03:32

Re: testing equality of two quaternions?

#4 19-Dec-2013 21:06:30

Re: testing equality of two quaternions?

#5 19-Dec-2013 21:25:01

Re: testing equality of two quaternions?

#6 19-Dec-2013 22:05:33

Re: testing equality of two quaternions?

#7 20-Dec-2013 00:17:13

Re: testing equality of two quaternions?

#8 20-Dec-2013 14:10:26

Re: testing equality of two quaternions?

#9 20-Dec-2013 14:26:47

Re: testing equality of two quaternions?

#10 20-Dec-2013 15:12:02

Re: testing equality of two quaternions?

#11 20-Dec-2013 16:05:55

Re: testing equality of two quaternions?

#12 20-Dec-2013 16:41:35

Re: testing equality of two quaternions?

#13 20-Dec-2013 21:12:18

Re: testing equality of two quaternions?

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