Sin, Cos, Tan? Any one know how!!

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Mega_Dib

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Posted: 28th Jan 2004 00:52

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Someone!! please help me!
Been programming for years but never bothered with angles,sin,etc.
Basically new project. Need formula for this.

Basic right-handed triangle.

******************* (enemy) Need rotation
* * for enemy
* *
* *
* *
* *
* *
* *
* *
**
(Your here)

I know all the sizes of the sides of the triangle, including the hypotenuse.
Obviously the lengths change at the enemies approach.I know Some Old Hens Can Always Hide There Old Age.(Rememberance for Trig). Experimented alot with all the Dark Basic Professional Trig, But cant get any results or come up with any algebra/equations to work. Im new to the Forums, so whos the best out there??
Thank you all for your help.

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Mega_Dib

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Posted: 28th Jan 2004 01:02

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The way the displayed the triangle looks nothing like that /\
||
Help!

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qwe

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Posted: 28th Jan 2004 01:13

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sin(a)=a/c
cos(a)=b/c
tan(a)=a/b
sin(b)=b/c
cos(b)=a/c
tan(b)=b/a

c is hypotenuse

i donno if this is only for right triangles.. or all triangles..

u kno there is "point object" command where you can point it to a 3d location

Dell Dimension 4550, Windows XP Home
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Mega_Dib

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Posted: 28th Jan 2004 01:24

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This is a 2D game. but thanks anyway Chris.
Just need to know how to convert sides of a triangle(which i know). Into an angle?

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Dave J

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Posted: 28th Jan 2004 02:19

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Quite simply:

Inverse Tan = First Side / Second Side

"Computers are useless they can only give you answers."

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Dave J

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Posted: 28th Jan 2004 02:22 Edited at: 28th Jan 2004 02:22

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Err, I might need to elaborate on that.

Tan-1 = (Opposite / Adjacent)

So if Opp = 6 and Adj = 2, the formula would go:

6 / 2 = 3

Atan(3) = 71.57

"Computers are useless they can only give you answers."

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Wik

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Posted: 28th Jan 2004 02:26 Edited at: 1st Mar 2004 04:12

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can't you use point object or something?

Anyway Mattman posted about this.
http://darkbasic.thegamecreators.com/?m=forum_view&t=21997&b=2

copied and pasted:
These functions are used to find leg legnths or angle measures in a right triangle.

in the following:

you can find the angle measure of A.
Since you know the angle OPOSITE of A and the ADJECENT leg measurements you use TANGENT because as darwin stated the tangent is the oposite over adjacent. you do 12/24 which is .5 so to find measure A you kit the TAN-1 key on a calqulator of use the arc-tangent command in DB and type in .5. The calqulator then figures out for you that the measure of angle A is 26.56505118

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Dave J

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Posted: 28th Jan 2004 02:31

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Sorry, what was that? My explanation wasn't good enough? Bah! Let's step it up a notch.

The whole theory behind Sin, Cos and Tan is the Unit circle, they each give a certain length at a certain angle. This diagram demonstrates:

At 30 degrees, each of the 3 functions will give a different length to the point where it meets the outer edge of the circle. Or where Tan reaches the Asymptote.

"Computers are useless they can only give you answers."

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DivW

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Posted: 28th Jan 2004 03:14

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Mwuahaha! Step it up more, Exeat! Let's talk about Radians!

Mwuahahaha!!!!!

Whoops...wnet a but mad there. I'm really good with Geometry maths, angles, degrees, etc. so you can e-mail me if you want someone to do all the maths for you. I don't mind doing it, i need to keep the old knife sharp after all...

And forget what i saidd about Radians. Radians are for complete bastard ruthless maths teachers who enjoy watching people squirm.

-Dave

[email protected]

PS: I'm putting up a website at some point about things like game maths. This will include how to make a sprite travel in a circle always facing forwards, how to break out of a circle, how to calculate time delays, etc...

But the info's in my head, if anyone else needs it i'm there. E-mail above.

Your soul...it tastes like chicken

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Phaelax

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Posted: 28th Jan 2004 03:18

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So you want to get the angle between you and the enemy?

+ Code Snippet

Rem Project: GetAngleFrom2DCoordinate
Rem Created: 16/07/2003 00:14:38
Rem Author: Lee 'Dr DB' Bamber :)

rem Set coordinates
youx#=320 : youy#=240

rem Main loop
do

rem Set moving target coordinate
targetx#=mousex() : targety#=mousey()

rem Calculate angle from YOUR position to TARGET position
dx#=targetx#-youx#
dy#=targety#-youy#
angle#=atanfull(dx#,dy#)

rem Clear screen
cls

rem Draw coordinates
circle youx#,youy#,5
circle targetx#,targety#,5

rem Show angle by drawing line
line youx#,youy#,newxvalue(youx#,angle#,100),newzvalue(youy#,angle#,100)
center text 320,260,"ANGLE = "+str$(int(wrapvalue(angle#)))

rem End loop
loop

"eureka" - Archimedes

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DivW

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Posted: 28th Jan 2004 03:28

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He didn't say anything about the angle...if it's 2D he might be looking for the co-ordinates...hmm...well if he is that's an even bigger bugger, but i can still do it

I'm such a geek...

Your soul...it tastes like chicken

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Dave J

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Posted: 28th Jan 2004 04:40

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Quote: "Mwuahaha! Step it up more, Exeat! Let's talk about Radians! "

Ok

To convert from the standard degress to radians you can multiply the number by Pi / 180, likewise, to convert from radians to degrees you can multiply the number by 180 / Pi. Eg:

50 * Pi / 180 = 0.873
50 Degrees = 0.87 Radians

Gah, that's it for me lol.

"Computers are useless they can only give you answers."

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Philip

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Posted: 28th Jan 2004 06:57

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You can also work out the angle from the dot product of the two vectors which represent the adjacent side and the hypotenuse. Thats the method I like to use. Why you ask? Because I'm crazy, I reply.

Philip

What do you mean, bears aren't supposed to wear hats and a tie? P1.3ghz / 384 megs / GeForce MX 5200 128meg / WinXP home

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Mega_Dib

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Posted: 28th Jan 2004 21:03

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Thanks for all your support people. Im going to try these new equations now. I will email you DivW, when i get stuck again, cheers

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DarkBASIC Professional Discussion / Sin, Cos, Tan? Any one know how!!