Character Rotation Amounts killing me!

[Jadd]

Hey!

I know it is possible, but I can't for the life of me remember the formula for it.

I need to find out how much you need to rotate from your current rotation to face an X + Y point, like so:


Please excuse my paint skillz...


Thanks in advance!

JetlagJad

[Kartio]

This is something that no man should know about.

[Jadd]

Uhh... What?

[SKU]

http://www.mmowned.com/forums/wow-me...-rotation.html
http://www.mmowned.com/forums/wow-me...-function.html

Hope that helps, it's in a slightly different context but the matter is the same.

[Jadd]

Lol I searched for rotation but didn't really find anything appropriate.

Looks like this could be right. Thanks for posting

[Cypher]

Don't they teach trig in QLD?

[Jadd]

I'm 14.

Filler.

[Cypher]

I'm 18, what's your point?

14 would mean you're in high school. Year 7 I assume (I think that's right for QLD...), either that or Year 8. At any rate, pretty sure they teach trig in either first or second year depending on your school.

I know that where I went to school they did. I remember we started trig in Year 7.

[Jadd]

For starters, I'm sure you've probably been doing this a lot longer than I have.

Secondly, I'm in year 9, and I've never even heard of 'trig'.

Thirdly, stop hiding your online status! >:P

Edit: I just asked my brother, and he learned it from year 10+

[Cypher]

Trigonometry - Wikipedia, the free encyclopedia

P.S. No. I'm always set to invisible. I like it better that way.

[AdamBowles]

Um, you need radian rotation?

I'm an A grade A Level maths student, so, do you still need any help?
I'm also 18, as it happens :P

Is it that you need to know how far to rotate to face a given coordinate from your current coordinate and rotation?

Edit:

I'm bored, so I'll go ahead and write out some formulae and information about the trigonometry required for this.

First a little explanation of radians.

One radian is the size of a circle sector (think slice of pie :D) required for the curved edge to be equal to the radius of this circle (the two straight edges). Radians are denoted by a super-script 'c' as opposed to the super-script 'o' used for degrees. One whole rotation in a circle happens to be equal to 2 * Pi (2π ~ 6.2.
To convert from degrees to radians you multiply by π/180, and thus you divide to return back to radians. Got that?

Now, in order to work out the rotation of one point to another, you need to work out the difference in the Y (north/south) direction, dy, and the difference in the X (east/west) direction, dx, obviously simple to obtain.

You can then use a theory suggested by good old Pythagoras, wherein the square of the hypotenuse of a right angled triangle is equal to the sum of the squares of the two remaining lengths. (a² + b² = c²).

Example:

Your character has (x, y) coordinates (100, 100) and you want to travel to (20, 40)

So dy = 100 - 40 = 60
dx = 100 - 20 = 80
and the magnitude of the total distance needed to travel = √(60²+80²) = √(3600 + 6400) = √(10,000) = 100 (coincidentally)

This means that the distance to your next coordinate = 100 from where your now standing.


Now to work out rotation to the new coordinate.

You need to imagine our set up as a triangle with the two ends of the hypotenuse as our start and end coordinate

We can use a formula to get the angles of this triangle straight out, and if you're in year 9, you most definitely will be learning this soon.

The formula is as follows:

a/Sin(A) = b/Sin(B)

Where a triangles sides and angles are labelled with capital letters representing the angles and the corresponding lower case letter representing the opposite side.

We'll use the right angle and the hypotenuse because we know both the angle and length to work out a number to compare with the other fraction.

A right angle is 90 degrees which in radians = 90 * π/180 = π/2

100/Sin(π/2) = 100/1 = 100

Using dx for the next side should give you the correct angle to use for your rotations

80/Sin(B) should also be equal to 100

this means that 80/100 = Sin(B)

so Arcsin(0. = B = 0.9272955218... radians

Say your character is currently facing directly north they would have to rotate by 180°, or π radians + the angle we worked out earlier, this totals to be 3.1415926535 + 0.9272955218 = 4.068888176 radians. Depending on the degree of accuracy you need for your implementation, you can decide where to round off, I'm guessing about 3 significant figures, in this case, 4.07 radians.

Oh, and all this working is clockwise, I'm sure you can also work out the amount needed to turn anti-clockwise.

I'm sure you can now work out how to change the rotation based off any random initial rotation, and the coordinates you need to travel toward.

Sorry if this post is a little long winded, but you can tell how much I love my subject, hah.

Best of luck to you.[/FONT]

[BoogieManTM]

Shynd has a good breakdown for people that don't know trig, too.

found here: Movement « Shynd’s WoW Modification Journal

[Jadd]

AdamBowles...

I can't thank you enough. This is probably the easiest way I've seen it done.

+Rep

[swollen]

I'm 18, what's your point?

14 would mean you're in high school. Year 7 I assume (I think that's right for QLD...), either that or Year 8. At any rate, pretty sure they teach trig in either first or second year depending on your school.

I know that where I went to school they did. I remember we started trig in Year 7.

I presume you were one of those kids that went to a snobby private school because your parents were rich then. We didn't start trig til at least year 9.

[Cypher]

I presume you were one of those kids that went to a snobby private school because your parents were rich then. We didn't start trig til at least year 9.

Hardly.

Welcome to Caringbah Online - The official Caringbah High School Website

That's where I went to school. Public school. Not private. Only difference is that it's academically selective.

If you're going to try and profile or stereotype it helps if you at least get it right. Dumbass.