How to bind a texture to a specific VAO?

Question

C++ / C#

How to bind a specific texture to a specific VAO, so that one object in the scene displays one texture, and another another?
And one more question - texture units are needed in order to display several textures on one object or for my purpose (and why can only 16 of them be used then)?

Answer 1

It is important to understand that in the days of shaders and megatextures, all this has become a convention.
A texture is just a huge raster that can store "textures" even from all objects in the scene - the question is in coordinates.
glBindTexture() // select a texture
glActiveTexture(GL_TEXTURE0) // attach it to a texture module
glBindTexture() // select another texture
glActiveTexture(GL_TEXTURE1) // attach it to another texture module
Create two samplers in the shader.
sampler2D a;
sampler2Db;
Load texture unit numbers into samplers:
glUniform1i( id_a, 0);
glUniform1i( id_a, 1);