opengl - does glBindTexture overwrite contents of the active texture unit

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I was finding the relationship between glActiveTexture(...) and glBindTexture(...) and I found an awesome answer here, the very top answer(the author/user Alfonse) gives us a pseudocode for how the both functions behave, and I understood most of it. But, in it he mentions in calls such as this: 

glActiveTexture(GL_TEXTURE0 + 5);
glBindTexture(GL_TEXTURE_2D, object);
glTexImage2D(GL_TEXTURE_2D, ...);

but one often binds a texture to the context just to upload some data or to modify it. It doesn’t matter at that point which texture unit you bind it to, so there’s no need to set the current texture unit. glTexImage2D doesn’t care if the current active texture is 0, 1, 40, or whatever.

So my problem is: when generating two texture we do something like this: 

 glGenTextures(1, &texture1);
glBindTexture(GL_TEXTURE_2D, texture1);
glTextureParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);

 glGenTextures(1, &texture2);
glBindTexture(GL_TEXTURE_2D, texture2);
glTextureParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);    


//some more code
//inside the render loop
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, texture1);
glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, texture2);

glDrawElements(...); glSwapBuffers();
//end of render loop

Notice, in the code before the render loop, I have used two texture glBindTexture(...) without calling glActiveTexture(...). Since, the default active texture unit is: GL_TEXTURE0, does this mean the parameters set for texture1 is overwritten by texture2?

opengl c++
1 Answers

No, texture parameters (set by glTexParameter) are set for a specific texture (the one that's currently bound to the active texture unit), not for a texture unit (not for one of GL_TEXTUREi, that is).

Note that your use of glTextureParameteri incorrect. Rather than GL_TEXTURE_2D, it expects a handle of a texture, as returned by glGenTextures1. You're confusing it with glTexParameteri, which indeed can be called with GL_TEXTURE_2D.

1 As noted by @derhass, glGenTextures (unlike glCreateTextures) merely reserves the handle. A texture with this handle is created only when you pass it to glBindTexture. It doesn't matter if you use glTexParameter, but if you want to use glTextureParameteri and other functions that operate directly on texture handles, it might be important.

user_27520750
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