Are there any tutorials out there that explain how I can draw a sphere in OpenGL without having to use
One way you can do it is to start with a platonic solid with triangular sides - an octahedron, for example. Then, take each triangle and recursively break it up into smaller triangles, like so:
Once you have a sufficient amount of points, you normalize their vectors so that they are all a constant distance from the center of the solid. This causes the sides to bulge out into a shape that resembles a sphere, with increasing smoothness as you increase the number of points.
Normalization here means moving a point so that its angle in relation to another point is the same, but the distance between them is different. Here's a two dimensional example.
A and B are 6 units apart. But suppose we want to find a point on line AB that's 12 units away from A.
We can say that C is the normalized form of B with respect to A, with distance 12. We can obtain C with code like this:
#returns a point collinear to A and B, a given distance away from A. function normalize(a, b, length): #get the distance between a and b along the x and y axes dx = b.x - a.x dy = b.y - a.y #right now, sqrt(dx^2 + dy^2) = distance(a,b). #we want to modify them so that sqrt(dx^2 + dy^2) = the given length. dx = dx * length / distance(a,b) dy = dy * length / distance(a,b) point c = new point c.x = a.x + dx c.y = a.y + dy return c
If we do this normalization process on a lot of points, all with respect to the same point A and with the same distance R, then the normalized points will all lie on the arc of a circle with center A and radius R.
Here, the black points begin on a line and "bulge out" into an arc.
This process can be extended into three dimensions, in which case you get a sphere rather than a circle. Just add a dz component to the normalize function.
If you look at the sphere at Epcot, you can sort of see this technique at work. it's a dodecahedron with bulged-out faces to make it look rounder.