How to rotate an object by a specific angle in OpenGL?

Question

Programming

So far, I can only rotate using glRotatef(theta, 0.1f, 0.1f, 0.0f);
I would like to learn how to rotate at a certain angle, something like this https://vk.com/videos57033099?z=video57033099_1714...

Answer 1

You need to learn how to apply geometric transformations to the input geometries (the vertices of your meshes).
In any case, this happens by calculating and using rotation matrices. For a mathematical background, google operations with matrices and vectors (linear algebra, computational geometry).
How to do this specifically in OpenGL depends on the API version you are using. If this is an "old" OpenGL, for example, version 2.0, then there is glRotate and other functions for operating with world and view transformation matrices. If this is OpenGL 3.0 and later, then read about vertex shaders and vertex transformations in shaders.

Answer 2

glRotatef(angle, x, y, z); rotates by angle around a vector (x, y, z). If you want to rotate about a specific axis, specify the rotation vector as follows: (1, 0, 0) - this is, for example, about the x-axis.

Answer 3

Learn matrices and quaternions.
Roughly speaking, multiplication by a matrix is ​​a rotation.
I'm not good with quaternions. But the principle is approximately the same, it is necessary to multiply or the type of that will be a turn))