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Topic: translate() the translate()? (Read 429 times) |
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kevinP
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translate() the translate()?
« on: Jan 29th, 2004, 11:41pm » |
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I'm beginning to get comfortable with translate(), etc. and can rotate objects now, etc. I also understand the idea behind the push/pop stack.
But I need a tip here. I'd like to create a planetary motion with a "moon". So larger object A is orbiting about a center point; at the same time a smaller object B is orbiting around object A.
So it seems that for object B, the translate() matrix needs to know where object A is (which I don't know how to do)... or is this simply a nested sort of thing?
Thinking aloud... I _do_ know the angle of rotation for object A, so I should be able to calculate its absolute position by using object A's centerpoint, the angle of rotation, and the radius from centerpoint to object A...
http://www.tiros.net/pfeiffer/processing/misc/planet.gif
-K
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| « Last Edit: Mar 20th, 2004, 1:38am by kevinP » |
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Kevin Pfeiffer
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benelek
 
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Re: transform the transform?
« Reply #1 on: Jan 30th, 2004, 1:41pm » |
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ah... you seem to be getting the hang of it - here's an example of how to do it. i hope my having given it to you doesn't take the fun out of the exercise!
Code:float r1, r2;
void setup() {
size(300,300);
noFill();
ellipseMode(CENTER_DIAMETER);
}
void loop() {
background(255);
stroke((int)random(255));
translate(width/2,height/2,0); //move to centre of screen.
rotate(r1); //rotate by first orbit.
line(0,0,100,0);
ellipse(100,0,10,10);
translate(100,0); //move 100 along rotation.
rotate(r2); //rotate by second orbit.
line(0,0,50,0);
ellipse(50,0,10,10);
r1+=0.02;
r2+=0.05;
} |
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kevinP
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Re: transform the transform?
« Reply #2 on: Jan 30th, 2004, 1:49pm » |
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Actually I was just thinking that I would delete my query because I think I have an idea now....
I'll give it one more go and then jump back to your answer (thanks for the help).
-K
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Kevin Pfeiffer
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mKoser
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Re: transform the transform?
« Reply #3 on: Jan 30th, 2004, 4:28pm » |
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jakob, whats up with the...
Code:
stroke((int)random(255));
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at first (without looking at the code) i thougt there was something strange going on with the rendering?
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mikkel crone koser | www.beyondthree.com | http://processing.beyondthree.com
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kevinP
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Re: translate() the translate()?
« Reply #4 on: Jan 30th, 2004, 7:53pm » |
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Here's what I finally came up with...
http://timo.iu-bremen.de/~pfeiffer/processing/2004/degrees_and_radians/
Attempted in the style of many of Casey's nice examples. It wasn't that complicated once I stopped and built a simplified model (similar to yours).
-K
(Finally corrected my subject line)
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| « Last Edit: Jan 30th, 2004, 8:09pm by kevinP » |
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Kevin Pfeiffer
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benelek
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Re: translate() the translate()?
« Reply #5 on: Jan 31st, 2004, 1:49pm » |
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nice piece of interactive geometry Kevin, though it seems (to me) a little annoying having the angle of rotation measured from the centre, while the actual rotation occurs from the top left.
ah, mKoser... it was late and i was tired... flashing shades of grey to keep me awake 
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kevinP
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Re: translate() the translate()?
« Reply #6 on: Jan 31st, 2004, 2:00pm » |
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on Jan 31st, 2004, 1:49pm, benelek wrote:| nice piece of interactive geometry Kevin, though it seems (to me) a little annoying having the angle of rotation measured from the centre, while the actual rotation occurs from the top left. |
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I'm reading about Feynmann (with quantum theory's 'action at a distance'). 
I appreciate the comment; it's easy to lose one's perspective after a while. Probably not enough visual user feedback (which was why I added the point center screen). Maybe I'll have another go at it later.
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Kevin Pfeiffer
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