Translating Angle into Xf and Yf?

Translating Angle into Xf and Yf? - Printable Version

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Translating Angle into Xf and Yf? - Z!re - 01-06-2005

Let's say I have an angle, and want to translate that into what I should add to a particles x and y

The way I used to do is:

Code:
ptcl.x = ptcl.x + xf

ptcl.y = ptcl.y + yf

Which works fine..
BUT
I'm making a particle engine, and i want to be able to specify by angle, instead of xf, yf:

Code:
angle = 167

ptcl.x = ptcl.x + Formula(angle)

ptcl.y = ptcl.y + Formula(angle)

Like:
0Âº, would become: xf = 0, yf = -2
45Âº, would become: xf = 1, yf = -1
90Âº, would become: xf = 2, yf = 0
270Âº, would become: xf = -2, yf = 0

etc, you get it (angles, and resulting xf, yf are just examples, doesent matter where 0Âº is)

Anyone know how to translate angle->(xf, yf).. and (xf, yf)->angle..?

Translating Angle into Xf and Yf? - Sterling Christensen - 01-06-2005

Code:
xf = magnitude * COS(angle)

yf = magnitude * SIN(angle)

Magnitude is how far along that angle it moved, angle is in radians.

Translating Angle into Xf and Yf? - l0wrd - 01-07-2005

Sterling is right. Those are the fomula, let me break it down for you.

In the two formula below R is the distance of the point from the origin (called radius, just like for a circle) and T is the angle (called theta) counter-clockwise from 0 on the x-axis.

Code:
X = r * Sin(T)

Y = r * Cos(T)

--
l0wrd, probably stalking you.

Translating Angle into Xf and Yf? - relsoft - 01-07-2005

Tot get the angle use:

Code:
a! = atan2(yd,xd)

Assuming you use FB.

Translating Angle into Xf and Yf? - Ralph - 01-30-2005

Finally, since BASIC, QuickBASIC and VB trig uses angles in radians, use somthing like this:

Code:
d2r = 3.141593/180 'where d2r means "degrees to radians multiplier"

.......

A = 90 'angle A in degrees

SineOfA = SIN(A*d2r)

By using the multiplier d2r and similar, you save a lot of writing and avoid a few errors.

You can also define a function, such as:

Code:
DEF FNsinD (A) = sin(A * 3.141593/189)

A = 90 'angle expressed in degrees

PRINT FNsinD(A) 'this will print the sine of 90 degrees, which = 1.

Translating Angle into Xf and Yf? - Z!re - 01-30-2005

Already knew that, but thanks anyways Big Grin