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Topic: Rotating an object about itself (Read 300 times) |
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Ride215
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Rotating an object about itself
« on: May 6th, 2004, 2:57am » |
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Hey everyone, I am trying to rotate an object about itself instead of the origin, but for some reason it moves to the x position of 0 instead of staying where I initially put it. The y position seems to stay the same. Where is my flaw?
Code:
float rot = 0.0;
int xPos = 150;
int yPos = 150;
int di = (int)sqrt(xPos*xPos + yPos*yPos);
void setup(){
size(300,300);
background(245);
framerate(20);
}
void loop(){
background(245);
ball();
rot += PI/48.0;
xPos = (int) (di*(sin(rot)));
yPos = (int) (di*(cos(rot)));
}
void ball(){
stroke(0);
fill(9 ;
rotate(rot);
rect(xPos,yPos,30,70);
}
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narain
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Re: Rotating an object about itself
« Reply #1 on: May 6th, 2004, 5:45am » |
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Hmm... Why are you doing one rotation yourself (the di*sin(rot) etc) and one using rotate()? I have a feeling those might be cancelling out or something.
This seems to work:
Code:translate(xPos,yPos);
rotate(rot);
rect(0,0,30,70);
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If you want it to rotate about its centre, you'll have to offset its corner using "rect(-15,-35, 30,70)".
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narain
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Re: Rotating an object about itself
« Reply #2 on: May 6th, 2004, 5:47am » |
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I forgot to mention, the above code works after removing the reassignments of xPos and yPos in loop().
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Ride215
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Re: Rotating an object about itself
« Reply #3 on: May 6th, 2004, 5:51am » |
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haha, wow, alright, that was so much simpler than I was making it now wasn't it.
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