OpenGL binding several 2D textures

Question

I've trying to load different textures to the GL_TEXTUREX variables and then assign them to different spheres. but so far I've having problems. I tried some of the suggestions in post like this and this but couldnt solve it.

This is part of my code:

GLuint textures[2];
void LoadTextures(std::string const& dirname)
{
glGenTextures(2, textures);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, textures[0]);
Image_t sun = loadPNG(std::string(dirname + "/sun.png"));
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, 1024, 512, 0, GL_RGB, GL_UNSIGNED_BYTE, &(sun.data[0]));  
glBindTexture(GL_TEXTURE_2D, textures[0]);

glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, textures[1]);
Image_t mercury = loadPNG(std::string(dirname + "/mercury.png"));
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, 1024, 512, 0, GL_RGBA, GL_UNSIGNED_BYTE, &(mercury.data[0]));  
}

and

void draw(void)
{

glEnable (GL_TEXTURE_2D);
glBindTexture (GL_TEXTURE_2D, textures[0]);
glPushMatrix();
glTranslatef(0.4,0,0);
gluSphere(sun, 0.5, 36, 36); //I want this sphere to use the texture GL_TEXTURE0
glPopMatrix();
glDisable(GL_TEXTURE_2D);
}

Answer 1

You need to call glBindTexture just before performing a draw call:

glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, textures[0]);

glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, textures[1]);

draw_things();

In the above example, whatever you draw with draw_things will have access to both textures 0 and 1 (GL_TEXTURE0 and GL_TEXTURE1).

Now, if what you want is to draw many things, but each with a different texture, then you need to:

glActiveTexture(GL_TEXTURE0); // activate any texture unit
glEnable(GL_TEXTURE_2D);      // make sure texturing is enabled

glBindTexture(GL_TEXTURE_2D, thing1_texture);
draw_thing1();

glBindTexture(GL_TEXTURE_2D, thing2_texture);
draw_thing2();

// etecetera