glCopyTexSubImage2D

OpenGL OpenGL: Basic Coding
1

My problem is that when I use
glCopyTexImage2D(GL_TEXTURE_2D,0,GL_RGBA,0,0,256,256,0);
to copy a texture from the frame buffer to update it, the new texture is greather than the original.
somebody knows why it happens?

2

If the original texture is smaller that the sub one, it’s normal.

3

The original texture and the final texture are the same.
I´m trying to render a texture using glCopyTexSubImage2D or glCopyTexImage2D, but the new updated texture is bigger than the original.
I don´t know what happens :’( with my code.
I have a 300x300 window and my texture is 256x256. I show my texture first and it´s ok. Then, I try to render it. I do this:

glBindTexture(GL_TEXTURE_2D, texture[0]);
glCopyTexSubImage2D(GL_TEXTURE_2D,0,0,0,0,0,256,256);

4

It wont shring your 300300 window into a 256256 texture. its just going to take the lower 256*256 pixels and transfer them to the texture, and it will look bigger

5

Try this :

32,32 ==> The position to add the texture

glTexSubImage2D(GL_TEXTURE_2D, 0, 32, 32, pTextureImage->sizeX,
pTextureImage->sizeY, GL_RGB, GL_UNSIGNED_BYTE, pTextureImage->data);

6

Thanks for your replies, it´s just fixed!!!
I change the window size to 256x256 and it works jjjj.

7

Now I have two textures:
texture[0] and texture[1]

With glCopyTexSubImage2D(GL_TEXTURE_2D,0,0,0,0,0,256,256), I change the texture previously selected with the function glBindTexture(GL_TEXTURE_2D, texture[1])

I want my texture[1] was the original texture.