Orbiting a sphere

Programming Questions

thunderba..

in Programming Questions • 1 year ago

Hello!

What mathematics are necessary to complete an orbit of the middle sphere? I only have the outer sphere going halfway around.

Thanks

float x, y;
float frequency = 2;
float angle;
float radius = 100;
void setup() {
size(400, 400, P3D);
background(255);
smooth();
fill(200);
}
void draw() {
lights();
background(255);
pushMatrix();
translate(200, 200, -50);
x = sin(radians(angle))*radius;
y = cos(radians(angle))*radius;
noStroke();
sphere(50);
stroke(255, 0, 0);
strokeWeight(3);
translate(x, 0, -100);
sphere(10);
angle += frequency;
popMatrix();
}

Replies(5)

tfguy44

Re: Orbiting a sphere

1 year ago

Make the orbiting sphere's translated position depend on both the calculated values of x and y, and not just x.

float x, y;
float frequency = 2;
float angle;
float radius = 100;
void setup() {
size(400, 400, P3D);
background(255);
//smooth();
noStroke();
}
void draw() {
lights();
background(255);
translate(200, 200, -50);
x = sin(radians(angle))*radius;
y = cos(radians(angle))*radius;
fill(200);
pushMatrix();
scale(50);
sphere(1);
popMatrix();
fill(255, 0, 0);
translate(x, 0, y);
scale(10);
sphere(1);
angle += frequency;
}

thunderba..

Re: Orbiting a sphere

1 year ago

Thank you!

I am curious, why are you using scale to change the size of the spheres? It works without it as well.

tfguy44

There used to be a bug with sphere() because the first value of the sphere's radius used would default 1 in the code that drew the sphere, instead of the specified radius. This would make one of the triangles that makes up the sphere be drawn incorrectly, which would leave a triangular hole in the top of the sphere. The work around was to make sure that all your spheres had a radius of 1 and were just scaled up to the proper size instead.

Old habits die hard!

scratchis..

Re: Re: Orbiting a sphere

1 year ago

Oh that's how you fix it :P (I still have this bug. Not a hole in the sphere, but a triangle sticking into the middle of it.)

Thanks!

thunderba..

Re: Orbiting a sphere

1 year ago

ah, that's pretty cool. thanks for sharing

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