changing the angle of an orbiting object in relation to the x-axis - Processing Forum

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riceje7

changing the angle of an orbiting object in relation to the x-axis

in Programming Questions • 1 years ago

so i have an object rotating in 3d space around another object. i have it orbiting at an angle (45 deg from the -x axis it looks like). but i want to change the angle at which it orbits in relation to the x-axis, effectively making the orbit either more horizontal or more vertical while looking down the z-axis. does anyone know how to go about doing this? here is the code im using to do the orbit:

CODE:

public void orbit() {
theta += this.vel.x;
theta = fixAngle(theta, TWO_PI);
this.loc.x = this.origin.x+orbitRadius*cos(theta);
this.loc.y = this.origin.y+orbitRadius*cos(theta);
this.loc.z = this.origin.z+orbitRadius*sin(theta);
println(loc);
}
private float fixAngle(float ang, float range) {
if (ang < 0)
ang += range;
else if (ang > range)
ang -= range;
return ang;
}

1

Replies(4)

Chrisir

Chrisir

Re: changing the angle of an orbiting object in relation to the x-axis

1 years ago

did you try:
this.loc.z = this.origin.z+orbitRadius*10;

replace 10 with another constant

Greetings, Chrisir

riceje7

Re: Re: changing the angle of an orbiting object in relation to the x-axis

1 years ago

i tried it and all that happens is the object oscillates back and forth, still at the same angle.

kritzikratzi

kritzikra..

Re: changing the angle of an orbiting object in relation to the x-axis

1 years ago

too lazy to talk much,

i added some comments inline!

PVector loc = new PVector();
PVector vel = new PVector();
PVector origin = new PVector();
float orbitRadius;
float theta;
void setup(){
size( 400, 400, P3D );
// i'm assuming this is constant, or comes from somewhere else ...
vel.x = 0.05;
// put the origin to the center of the screen
// pick some arbitrary orbitRadius
origin.x = width/2;
origin.y = height/2;
orbitRadius = width/4;
frameRate( 200 ); // to give nice trails
}
void draw(){
hint(DISABLE_DEPTH_TEST); // trick to clear the z-buffer
hint(ENABLE_DEPTH_TEST); // trick to clear the z-buffer
noStroke();
fill( 0, 10 );
rect( 0, 0, width, height );
orbit();
fill( 255 );
translate( origin.x, origin.y );
// so here's the idea:
// you don't change anything about your orbits,
// you just roatate the coordinate system you're drawing to.
rotateX( mouseY*TWO_PI/height );
rotateY( mouseX*TWO_PI/height );
// draw the x-y-z coordinate system to avoid confusion a bit ...
// you'll see that the orbit always lies in the x-y plane (the green-red lines)
stroke( 255, 0, 0 );
line( 0, 0, 50, 0 );
stroke( 0, 255, 0 );
line( 0, 0, 0, 50 );
stroke( 0, 0, 255 );
line( 0, 0, 0, 0, 0, 50 );
translate( loc.x, loc.y, loc.z );
noStroke();
fill( 255 );
sphere( 5 );
}
void orbit(){
theta += vel.x;
// planetary orbits are (as long as only one sun is involved) 2d only.
// it's enough to calculate x and y.
// later we rotate the enitre x-y plane.
// note though that we only care about the distances from the origin
loc.x = orbitRadius * cos( theta );
loc.y = orbitRadius * sin( theta );
}

riceje7

Re: Re: changing the angle of an orbiting object in relation to the x-axis

1 years ago

awesome that did the trick, thanks for the help.

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