Array texture in OpenGL 3.+ with mipmap

Question

I have read this tutorial: Array Texture , but I don't want to use the glTexStorage3D()(requires OpenGL 4.2) function. First of all, can someone check whether I have implemented this code properly(I'm using glTexImage3D instead of glTexStorage3D):

unsigned int nrTextures = 6;
GLsizei width = 256;
GLsizei height = 256;
GLuint arrayTextureID;
std::vector<unsigned char*> textures(nrTextures);

//textures: Load textures here...

glGenTextures(1, &arrayTextureID);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D_ARRAY, arrayTextureID);

//Gamma to linear color space for each texture.
glTexImage3D(GL_TEXTURE_2D_ARRAY, 0, GL_SRGB, width, height, nrTextures, 0, GL_RGB, GL_UNSIGNED_BYTE, NULL);

for(unsigned int i = 0; i < nrTextures; i++)
    glTexSubImage3D(GL_TEXTURE_2D_ARRAY, 0, 0, 0, i, width, height, 1, GL_RGB, GL_UNSIGNED_BYTE, textures[i]);

/*glTexParameteri(GL_TEXTURE_2D_ARRAY, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);*/
glTexParameteri(GL_TEXTURE_2D_ARRAY, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D_ARRAY, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D_ARRAY, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D_ARRAY, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

/*glGenerateMipmap(GL_TEXTURE_2D_ARRAY);*/

glBindTexture(GL_TEXTURE_2D_ARRAY, 0);

How do I implement mipmapping with this implementation?

Answer 1

This mostly looks ok. The only problem I can see is that GL_SRGB is not a valid internal texture format. So the glTexImage3D() call needs to use GL_SRGB8 instead:

glTexImage3D(GL_TEXTURE_2D_ARRAY, 0, GL_SRGB8, width, height, nrTextures, 0,
             GL_RGB, GL_UNSIGNED_BYTE, NULL);

For generating mipmaps, you can call:

glGenerateMipmap(GL_TEXTURE_2D_ARRAY);

after you filled the texture with data with the glTexSubImage3D() calls.