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Index › Discussion › Exhibition › Rotating Ellipse
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Rotating Ellipse (Read 2031 times)
Lasrin
Rotating Ellipse
Mar 20th, 2009, 5:53am  
Ok, bear with me here, this is my first sketch I'm posting.  I lost a lot of hair to this one (had to remember a bit of my geometry from HS), anywho, here it is, please enjoy.. .

float fi = 0;
int ctrX;
int ctrY;

void setup() {
 size(150,150,P3D);
 ctrX = width/2;
 ctrY = height/2;
 background(0,0,0);
 stroke(0,0,0);
 fill(0,255,0);
}

void draw() {
 background(0,0,0);
 RotateEllipse();
}

void RotateEllipse() {
 if (fi > TWO_PI)  { fi = 0; }
 translate(ctrX,ctrY);  // center the ellipse in the window
 rotate(fi);
 // rotateX(fi);  // flipping top to bottom
 // rotateY(fi);  // flipping right to left
 // rotateZ(fi);  // spinning
 ellipse(sin(fi),cos(fi),60,10);
 fi = fi + 0.1;  // 0.01=crawl, 0.1=slow, 0.9=blur, 1.5=blur(x2)
}
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Lasrin Xefativ, Exiled Lord of Chaos
Devote' to the Platypus Messiah first order of the Skittle
Lasrin  
Diabeticrabbit
Re: Rotating Ellipse
Reply #1 - Mar 21st, 2009, 1:14am  
It looks very interesting.

But may i ask what is it for? Is it part of a project or just a proccessing experiment?
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Lasrin
Re: Rotating Ellipse
Reply #2 - Mar 23rd, 2009, 7:35pm  
It's part of a GUI for an RC submarine.  I needed a way to model the dive planes, and the sub itself, and using rotating lines was less than satisfying.

The GUI will use wireless Ethernet to connect to an arduino in the sub.
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Lasrin Xefativ, Exiled Lord of Chaos
Devote' to the Platypus Messiah first order of the Skittle
Lasrin  
clankill3r
Re: Rotating Ellipse
Reply #3 - Mar 24th, 2009, 4:44pm  
can someone explain why it looks so strange when I put smooth on?
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PhiLho 
Re: Rotating Ellipse
Reply #4 - Mar 24th, 2009, 5:30pm  
Just look at the last paragraph of smooth() reference...
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WWW  
Lasrin
Re: Rotating Ellipse
Reply #5 - Mar 25th, 2009, 6:06pm  
Arg!  When I have this part of the GUI, all the shapes rotate!  Does anyone know how to unrotate, or to turn rotate off?


> ah, if I put this line : rotate(-fi);
> after the ellipse, it allows other shapes to not rotate.
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« Last Edit: Mar 25th, 2009, 7:09pm by Lasrin »  
Lasrin Xefativ, Exiled Lord of Chaos
Devote' to the Platypus Messiah first order of the Skittle
Lasrin  
koogy
Re: Rotating Ellipse
Reply #6 - Mar 26th, 2009, 12:07pm  
look at pushMatrix and popMatrix

http://processing.org/reference/pushMatrix_.html
http://processing.org/reference/popMatrix_.html

pushMatrix, rotate, draw your ellipse, popMatrix...
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Lasrin
Re: Rotating Ellipse
Reply #7 - Mar 26th, 2009, 9:43pm  
The push/pop Matrix stuff only works if you push onto the stack, or pull/pop off the stack in the exact same order, and has a limit of 32 "pushes".  The rotating ellipse, with an open step, can have 360 (or more) variations.  Maybe I'm not understanding the theory behind stacks.
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Lasrin Xefativ, Exiled Lord of Chaos
Devote' to the Platypus Messiah first order of the Skittle
Lasrin  
PhiLho 
Re: Rotating Ellipse
Reply #8 - Mar 27th, 2009, 1:05am  
Quote:
Maybe I'm not understanding the theory behind stacks.

I think so too...  Grin
The idea is that inside a draw() call, you push before rotating a shape, do your transformations, draw the shape, then pull. And you do that for each shape needing transformations independently of the others.
No need, in general, to stack these calls.
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Lasrin
Re: Rotating Ellipse
Reply #9 - Mar 27th, 2009, 9:26pm  
Thank you!  That makes more sense.  I'm self learning on this, as such, am a bit slower than the average bear. Smiley
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Lasrin Xefativ, Exiled Lord of Chaos
Devote' to the Platypus Messiah first order of the Skittle
Lasrin  
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