Find Major / Minor Arc In Circle?

[ProdigyX]

Ohla ladies and gentlemen!

So I have a perplexing question, but i will ask it in 2 parts

Part One.
How can I find the arc angle measurements of a circle if i have 2(or 3) points on the circumference of a circle?

[Pixelthief]

Hrmm, what do you know about this circle? If you know its center and radius (radius not necessary) you can easily find it by trigonometry; find the angle between the points and the center of the circle, then find the difference between those two angles. Thats your arc.

Now if you only know the location of the points themselves, you need a minimum of 3 points to be able to find the arc (or else theres an infinite amount of circle solutions)

If thats the case, this might be instructive;
http://paulbourke.net/geometry/circlefrom3/

[ProdigyX]

Gotcha,

I will always know the origin of the circle. (The middle of my player object)
I will also always know 2 points on the circumference of the circle (The player right click 2 times and i store the x & y values of each point)

From these 2 points on the circumference, I can find both the Minor and Major Arc angles (Do what you do and then subtract that value from 360).

Part 2 of the question is this;

Is there some kind of gesture recognizing feature extension, or something I can use to track the "shape/movement trail" of the mouse?

In my game, the player will be able to fire a beam of energy at a specific location of their choosing. (They simply click 2 locations and everything in between there is fired upon). The main problem with this method is that sometimes it it will fire the major arc (300 degrees for example) when the player wanted to fire the minor arc (60 degrees). In some situations however, the player WILL want to fire the major arc over the minor arc.

The solution to this could be to track the trail the mouse follow. (That way the player would only have to click & drag the mouse to fire the weapon/energy beam instead of clicking twice).

If you need an example of what this problem in action, I can upload the .mfa and link it here

So the real question is this;
What can I do to distinguish the major arc from the minor arc and vice versa if the player can only click & drag the mouse, or click twice?

[LB]

If the difference between the angles is more than 180, just shoot the other direction and be cautious of the 0/360 trap.

[ProdigyX]

I mean shooting the major/minor arc is situational. I want the player to be able to shoot one, not just the minors arcs, or just the majors arcs. A player might NEED to shoot a 330 degree arc. I need to find a way for the player to be able to do both

[LB]

OH, I know what you mean. That's tricky but not too hard; I'll make an example...

EDIT: Turning out much harder. Eliyahu and I are working on it but we need to sleep on it tonight...

[ProdigyX]

Thank ya very much

[ProdigyX]

A work around to this, MAY to lock the cursor into a circle upon an event. I've tried this, and never got my trig formula to work.

Perhaps I'm simply overthinking the trig formula.

What the the possible ways to lock the cursor to move only in a perfect circle upon an event?

[LB]

You could have an object locked to a perfect circle and thus give the user a visual representation of where they will shoot, or you could make it invisible if you wanted. Either way I don't think you should be hiding the mouse.

I am still trying my luck with this and it is tricky all right, I have the right concept, but I can't find the right way to implement it...

[ProdigyX]

The mouse won't be hidden in the least bit.

I just need it to move in a circle and only a circle at certain times. However upon more thinking, I think I found a flaw in my work around.

By lock I mean instead of anywhere movement, make it only a circular movement, not keep it in one place, or make it hidden :P

The particle spray object find the shortest direction to fire to naturally. (For example, if you tried to fire 18 to 8 going counter clockwise, the long way, it would fire 18 to 8 the short way) To fix this, all one had to do is is 32 to either the starting direction value, or the ending direction value depending on the situation