OpenGL Render to texture (FBO) does not work - c++

Question

I'm trying to use FBO to render to texture and then display the texture, but all I get is a black rectangle. My code is:
Initialization:
#include <GL/glew.h>
#include <GL/gl.h>
#include <GL/glext.h>
#include <assert.h>
// ...
GLuint fbo_, rbo_, tex_;
glGenFramebuffers(1, &fbo_);
glBindFramebuffer(GL_FRAMEBUFFER, fbo_);
glGenRenderbuffers(1, &rbo_);
glBindRenderbuffer(GL_RENDERBUFFER, rbo_);
glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT, width_, height_);
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, rbo_);
glGenTextures(1, &tex_);
glBindTexture(GL_TEXTURE_2D, tex_);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, width_, height_, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
glGenerateMipmap(GL_TEXTURE_2D);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, tex_, 0);
assert(glCheckFramebufferStatus(GL_FRAMEBUFFER) == GL_FRAMEBUFFER_COMPLETE);
glBindFramebuffer(GL_FRAMEBUFFER, 0);
Render to the FBO:
glPushAttrib(GL_VIEWPORT_BIT);
glViewport(0, 0, width_, height_);
glBindFramebuffer(GL_FRAMEBUFFER, fbo_);
//draw stuff
glPopAttrib();
glBindFramebuffer(GL_FRAMEBUFFER, 0);
Use the texture (the problem is probably in the code above, because if I just use some static texture, the code below works):
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, tex_);
glBegin(GL_QUADS);
glTexCoord2f(0, 0);
glVertex3f(x_, y_, 0);
glTexCoord2f(width_, 0);
glVertex3f(x_ + width_, y_, 0);
glTexCoord2f(width_, height_);
glVertex3f(x_ + width_, y_ + height_, 0);
glTexCoord2f(0, height_);
glVertex3f(x_, y_ + height_, 0);
glEnd();
Could you help me spot the problem?

Answer 1

Make sure the texture you attach is complete if you're going to rely on the default texture environment.

Answer 2

I had the same problem and used genpfault's advice to create a complete texture. Unfortunately, I do not have enough reputation to add a comment so I just added this answer here. Still, the code below may save you some time:
// generate full viewport texture
glGenTextures(1, &fb_tex);
glBindTexture(GL_TEXTURE_2D, fb_tex);
// IMPORTANT: texture must be COMPLETE (mipmaps must be specified..
// or the following parameters can be used if there are none)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_BASE_LEVEL, 0);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, 0);
glTexImage2D(
GL_TEXTURE_2D,
0,
GL_RGBA,
width,
height,
0,
GL_RGBA,
GL_UNSIGNED_BYTE,
NULL
);
The only thing I changed in my original code was two add the two lines with glTexParameteri. The parameters can be changed depending on the amount of mipmaps you want/have.