Scratch

AtomicBawm3 · 2011-05-20 22:04:40

I'm trying to determine the distance to the edge of an ellipse with a given direction.

I have variables for both radii of the ellipse on the x and y scales, what I want to do is find the x and y on the ellipse when I have a given direction from the center so that I can calculate the distance at that given direction/point.

How would I do this?

Kileymeister · 2011-05-20 22:07:53

I think that can be achieved through simple sine and cosine trigonometry.

X= sin(direction)*xradius
Y=cos(direction)*yradius

EDIT: This for portal sensing? I know what you're up to wink

Last edited by Kileymeister (2011-05-20 22:16:15)

AtomicBawm3 · 2011-05-20 22:15:08

Kileymeister wrote:
I think that can be achieved through simple sine and cosine trigonometry.

X= sin(direction)*xradius
Y=cos(direction)*yradius

Note: This is using Scratch direction, not math direction. For math direction, use "-1(direction-90)". (This note was actually kind of unnecessary, but whatever)

EDIT: This for portal sensing? I know what you're up to

Yeah, I figured that out before you posted, but no, I'm not. I'm actually working on a radial gradient effect.

AtomicBawm3 · 2011-05-20 23:10:27

hmm...my overall equation isn't working though. Here's the design it produces, though it's different cuz I changed it so it's easier to see what happens:

My equation for the radial distance is the one messing up, I'm sure:

x=radius1*sin(atan(x-centerx/y-centery))
y=radius2*cos(atan(x-centerx/y-centery))

Then it uses the distance formula, distance=sqrt(x^2+y^2)

I've tried several variations of this, but they haven't worked. Anyone got any ideas why it's not doing it right?

AtomicBawm3 · 2011-05-21 09:31:49

Bump. Anyone?

If you need more information to figure this out:

the color= color1-((color2-color1)*(distance/radial distance)

So basically, when the ratio of distances is small, it's more color1, but if it's higher, it's more color2.

AtomicBawm3 · 2011-05-21 10:59:40

Ok, so I think I figured out what it's doing, but I don't understand why. It's drawing 2 circles around the focii of the ellipse. So if I make the focii equal (i.e. circle) it's fine, but if the radii are different (and thus, the focii are different), it doesn't work.

Scratch

archived forums

#1 2011-05-20 22:04:40

Some complex math help

#2 2011-05-20 22:07:53

Re: Some complex math help

#3 2011-05-20 22:15:08

Re: Some complex math help

Kileymeister wrote:

#4 2011-05-20 23:10:27

Re: Some complex math help

#5 2011-05-21 09:31:49

Re: Some complex math help

#6 2011-05-21 10:59:40

Re: Some complex math help

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