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# Small Question about code that rotates a "shape"

edited July 2016

I'm trying to make rotating polygon on processing, but I'm having a bit of trouble... The way the project will eventually work is that there will be an n-sided polygon, made out of lines, and the polygon rotates 360°. Right now, I'm just interested in having a single line be able to make a full rotation and change its angle as its rotating.

The line in the project works as intended (sort of), but I can't seem to increase the size of it without drastically increasing the speed

http://www.openprocessing.org/sketch/376656

Any and all help is appreciated!

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## Answers

• edited July 2016 Answer ✓

could it be any solution for you?

``````class movableLine{
float vx, vy;
float lineLen;
float x1, y1;

float angle, angleConst;
movableLine(float x1, float y1, float lineLen, float angle)
{
this.x1 = x1;
this.y1 = y1;
this.lineLen = lineLen;
this.angle = angle;
this.angleConst = angle;
}

void display()
{
pushMatrix();
translate(x1,y1);
rotate(angle);
line(-lineLen/2,0,lineLen/2,0);
popMatrix();
}

void changeSpeeds()
{
vx = 10* cos(angle);
vy = 10 * sin(angle);
angle += angleConst;
}

void move()
{
x1 += vx;
y1 += vy;
}
}

void setup()
{
size(500, 500);
background(255, 255, 255);
color(0, 0, 0);
}

movableLine oneLine = new movableLine(0., 0., 50, PI/32);
void draw()
{
background(255, 255,255  );
translate(width/2, height/2);
oneLine.move();
oneLine.display();
oneLine.changeSpeeds();

}
``````
• edited July 2016

This works incredibly well! Thank you very much!

If you don't mind me asking... Why'd you change the display() method to have a push/popMatrix()? I'm having trouble understanding the translate(x1, y1) part, as well well as changing the move() method to only affect x1 and y1?

Again, thank you very much for solving my question

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