Peasy Cam rotation

edited June 2016 in Library Questions

Hi, I'm trying to create a button that rotates my object perfectly 90 degrees to the left from it's initiate state.

I made a button that when it is triggered, it will execute the following code.

cam.reset(); // Resets the camera so that the object is in its initial state.
cam.rotateY(-PI/2); // cam.rotateX(-PI/2);

However, every time I press the button, cam.reset() will be executed but not rotateX(). And when I execute rotateX() by itself, it works. Hence, I think that it is the cam.reset() that nullifies the rotateX() that comes after it.

Does anyone know a way to prevent this from happening? Or does anyone know how to reset the 3d object to its initial position without using cam.reset()?

Thank you so much, Jerry



  • are you using a double? try using (double)(PI / 2) as the argument.

  • edited June 2016

    also, what is your object? would you be able to tell if it had been rotated 90 degrees in Y?

  • edited June 2016

    try using (double)(PI / 2) as the argument.

    Constant PI has already lost precision when it was converted from double to float:

    println(PI, Math.PI); // 3.1415927 3.141592653589793
    println(HALF_PI, .5d * Math.PI); // 1.5707964 1.5707963267948966
  • i was more worried about the type than the precision. he's saying it doesn't work, not that it's slightly inaccurate.

  • edited June 2016

    Java automatically coerces up all numerical types to double when at least 1 of the operands is double.

    For example: PI + Math.PI results type double, b/c the 2nd operand is double.
    Same for Math.E + 'A', which also evals to double. :-B

  • runnable example, shows the same problem

    import peasy.*;
    PeasyCam cam;
    void setup() {
      size(600, 600, P3D);
      cam = new PeasyCam(this, 200);
      stroke(255, 0, 0);
      fill(0, 255, 0);
    void draw() {
      box(100, 100, 100);
    void keyReleased() {
      cam.rotateX((double)(PI / 4.0));

    where's the double in -PI/2 ?

  • Answer ✓

    replace the cam.rotate() with cam.setRotations(0, HALF_PI, 0); and that works. i think cam.rotate() works within dra() but not as an absolute, if you see what i mean. just a theory, which i'm testing now...

  • yes, add cam.rotateY(.02); after line 15 and it'll sit there happily rotating.

    not sure why it should work like this though.

  • edited June 2016

    Alas... if PeasyCam's rotateX() method only accepts double as its argument, no matter which numerical datatype we pass to it, it's gonna be automatically coerced to double.

    If it's the case it's desirable to pass double's full precision, we should use Math's double PI, not PConstants's float PI:

    cam.rotateX(Math.PI * .25d);

    Besides, Processing already got QUARTER_PI which is PI/4f btW: ;;)

  • Hey, thank you guys for your advice! I tried out using changing the inputs into doubles. However that didn't work

  • The object is a box(500);

  • Hi Koogs, the set rotations thing works! Thank you so much!

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