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Index › Programming Questions & Help › Syntax Questions › rotation

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rotation (Read 1764 times)

annemarie

rotation
Jan 20^th, 2006, 9:48am

Hi,

Maybe someone can help me with the code below. I want the white triangle to turn around its own center with mouseX movement only. How do I do that?

float x, y;

void setup()
{
size(200, 200);
x = width/5.0;
y = height/5.0;
noStroke();
framerate(30.0);
smooth();
}

void draw()
{
background(51);
float a = atan2(mouseY-y, mouseX-x);

translate(x, y);
rotate(a);
stroke(255, 0, 0);
curve(500, 200, 0, 0, 300, 300, 500, 200);
beginShape(POLYGON);
vertex(100, 20);
vertex(50, 50);
vertex(30, 30);
endShape();
}

Ira

Re: rotation
Reply #1 - Jan 20^th, 2006, 4:17pm

If I understood your question correctly, you'll want the triangle's center point to be set on the origin (0,0) when you translate to the mouse postion. If you want rotation based on the mouse's x pos you can just pass the mouseX value (converted to radians) to rotate(). To increase the rotations based on mouse movement, multiply mouseX by some value, e.g. rotate(radians(mouseX*1.5))
Try this:
Code:

 
void setup()  
{  
  size(200, 200);  
  noStroke();  
  framerate(30.0);  
  smooth();  
}  
 
void draw()  
{  
  background(51);  
  translate(mouseX, mouseY);
  rotate(radians(mouseX)); //multiply mouseX to increase rots
  stroke(255, 0, 0);  
  curve(500, 200, 0, 0, 300, 300, 500, 200);  
  beginShape(POLYGON);
  vertex(35, -15);
  vertex(-15, 15);
  vertex(-35, -5); 
  endShape();
}

Hope this helped.

ira

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Ira

Re: rotation
Reply #2 - Jan 20^th, 2006, 4:46pm

I just reread your post(sorry I'm groggy), you can keep the triangle where it was and have it rotate around itself as well.
Code:


 float x, y;
 void setup()  
{  
  size(200, 200);  
  noStroke(); 
  x = width/5.0;  
  y = height/5.0;   
  framerate(30.0);  
  smooth();  
}  
 
void draw()  
{  
  background(51);  
  translate(x, y);
  rotate(radians(mouseX)); //multiply mouseX to increase rots
  stroke(255, 0, 0);  
  curve(500, 200, 0, 0, 300, 300, 500, 200);  
  beginShape(POLYGON);
  vertex(35, -15);
  vertex(-15, 15);
  vertex(-35, -5);  
  endShape();
}

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