GEO and TRIG whizzzs quick question....

[pds 0]

i want to get the heading (or angle), in degrees, of an arbitrary point (x,y) relative to 0,0.

e.g. skydiver icon at 0,0 and i want it to face the mouse cursor. capisce?

and iffn you don't have the answer, please tell me what it is i am asking for in proper terminology so i can inquire elsewhere.

FANKYU!

namaste, motherfucker.

[sunshine 2]

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and iffn you don't have the answer, please tell me what it is i am asking for in proper terminology so i can inquire elsewhere.

The proper way to say it is:

Can i have another shot of tequila please?

___________________________________________
meow

I get a Mike hug! I get a Mike hug!

[MWGemini 0]

PM sent.

Mike

[pds 0]

Quote

Quote

and iffn you don't have the answer, please tell me what it is i am asking for in proper terminology so i can inquire elsewhere.

The proper way to say it is:

Can i have another shot of tequila please?

namaste, motherfucker.

[pds 0]

got it thanks to a helpful hint from MWGemini.

he says i want the inverse tangent. which make sense. given his nutshell trig refresher and some twiddling got exactly what i needed.

FANKYU! i'll have that shot of tequila now.

namaste, motherfucker.

[pilotdave 0]

You're getting me all excited again.

edit: not about the math.

Dave

[pds 0]

Quote

You're getting me all excited again.

edit: not about the math.

Dave

namaste, motherfucker.

[Remster 30]

tang alpha = y/x
so tan-1 (x/y) = alpha

Alpha being the angle in radians.

To converts to deg, use 180 deg = pi radians

Remster

[pds 0]

Quote

tang alpha = y/x
so tan-1 (x/y) = alpha

Alpha being the angle in radians.

To converts to deg, use 180 deg = pi radians

yes. but computer don't know how to speak trig

this is what i came up with after my trig lecture with mwgemini. rather elegant if i do say so mesef

function relativeCoordsToHeading(x,y)

{

var radians = Math.atan2(x,y);

var degrees = (eval(radians))*(180/Math.PI);

if (x>0){degrees = 180 - degrees;} else {degrees = -degrees + 180;}

return degrees;

}

namaste, motherfucker.

[Remster 30]

So you want us to do all the work, is that it????

Remster

[pds 0]

Quote

So you want us to do all the work, is that it????

uh oh, is it that obvious?

is an old programmer trick.

ok, it's an old guy trick recycled: if you keep doing a crappy job at doing the dishes and washing the clothes she finally stops asking you to do it!

namaste, motherfucker.

[penniless 0]

Quote

Quote

tang alpha = y/x
so tan-1 (x/y) = alpha

Alpha being the angle in radians.

To converts to deg, use 180 deg = pi radians

yes. but computer don't know how to speak trig

this is what i came up with after my trig lecture with mwgemini. rather elegant if i do say so mesef

function relativeCoordsToHeading(x,y)

{

var radians = Math.atan2(x,y);

var degrees = (eval(radians))*(180/Math.PI);

if (x>0){degrees = 180 - degrees;} else {degrees = -degrees + 180;}

return degrees;

}

Does it work in your application? There's something a bit funny about your if/else statement, since (180-degrees) is the same as (-degrees +180)

[Cornholio 0]

SOHCAHTOA

That's your answer.

Glad I could help.

Butthead: Whoa! Burritos for breakfast!
Beavis: Yeah! Yeah! Cool!
bellyflier on the dz.com hybrid record jump

[lummy 4]

the answer's right here!!

I promise not to TP Davis under canopy.. I promise not to TP Davis under canopy.. eat sushi, get smoochieTTK#1

[pds 0]

Quote

Does it work in your application? There's something a bit funny about your if/else statement, since (180-degrees) is the same as (-degrees +180)

ummm, not.

you are breaking a fundamental rule of logic. you are assuming, wrongly given the conditional you base your statement on, that the degree is the same in both expressions.

works great. try it.... dzDivepool beta

edit: it has to do with quadrants as per mwgemini. if x is negative it returns a negative angle. this is not what i want. -(-45 ) + 180 = 225 is what i want. or sumthing. dunno. i fudged around and it works. go figure.

cheers

namaste, motherfucker.

[pds 0]

Quote

the answer's right here!!

i didnt know the question retard!

namaste, motherfucker.

[lummy 4]

LOL... I've been waiting to use that one..

I promise not to TP Davis under canopy.. I promise not to TP Davis under canopy.. eat sushi, get smoochieTTK#1

[MWGemini 0]

Glad I could help. I realized after I signed off that the numbers I gave you for converting the angle based on quadrant location would need to be changed. My math was based on the circle being 0 to 2pi radians, but Javascript returns the value in negative pi to pi radians. Glad I could help.

Mike