spherical movement of camera based on mouse movement

Programming Questions

riceje7

spherical movement of camera based on mouse movement

in Programming Questions • 2 years ago

i am trying to figure out how i can move the basic camera rig in manner that would have it able to move to any point along a sphere all while looking at a central point (i.e. the center of the scene would be (0, 0, 0)). I'm pretty sure i need to use spherical coordinates but I'm not sure how to implement the equations. any help would be greatly appreciated.

Replies(4)

quarks

Re: spherical movement of camera based on mouse movement

2 years ago

There is already a very easy to use library that does precisely what you describe it is called PeasyCam

riceje7

Re: Re: spherical movement of camera based on mouse movement

2 years ago

i should have mentioned i'm developing in android mode, i tried peasycam and it isn't compatible so i'll need the equations to do it that way.

Greger

Re: spherical movement of camera based on mouse movement

2 years ago

What you want are spherical coordinates

From wikipedia we find:

x = r * sin(t) * cos (b)
y = r * sin(t) * sin(b)
z = r * cos(t)

so you need to calculate x,y,z from r,t,b

r = radius of the sphere, so that will probable be constant in your case

t and b is how far around the sphere, and how far from top to bottom it is. you just gotta try what each is.

so you can have a function like:

PVector xyz(float r, float t, float b)
{
PVector t = new PVector(0, 0, 0);
t.x = r * sin(t) * cos (b);
t.y = r * sin(t) * sin(b);
t.z = r * cos(t);
return t
}

Just remember that t and b are expressed in radians and not degrees.

riceje7

Re: Re: spherical movement of camera based on mouse movement

2 years ago

okay this is what i have so far:

PVector xyz = new PVector(0, 0, 500);
float radius = PVector.dist(new PVector(0, 0, 0), xyz);
float theta = PVector.angleBetween(new PVector(0, radius, 0), xyz);
float phi = PVector.angleBetween(new PVector(0, xyz.y, sqrt((radius*radius-xyz.y*xyz.y))), xyz);
xyz.x = radius*sin(theta)*cos(phi);
xyz.y = radius*sin(theta)*sin(phi);
xyz.z = radius*cos(theta);
camera(xyz.x, xyz.y, xyz.z, 0, 0, 0, 0, 1, 0);

i am finding the inclination angle (theta) and the azimuth angle (phi) and i plug those in to find the x, y, and z based on the spherical coordinates. I'm just not sure where i need to plug in mouseX and mouseY to get the movement i need. has anyone done this before? any help would be awesome.

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