#framebuffer cropped

1 messages · Page 1 of 1 (latest)

novel shoal
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Hejhej! I'm trying to work my way through this lecture
https://www.youtube.com/watch?v=ifD31g_ZdEo&list=PLplnkTzzqsZS3R5DjmCQsqupu43oS9CFN&index=12
combined with this tutorial:
https://learnopengl.com/Advanced-OpenGL/Framebuffers
I was stuck a couple of times, but I really have no Idea now what to do.
first picture: The teapot before I used a framebuffer
2nd: the teapot drawn on the quad
3rd: potential problem? The size seems to be reassigned
4th: potential problem: The renderbuffer only uses a fragment of the sace it should.
I'm assuming, that I have to create a framebuffer, bind it. Attach a texture to it, then draw to that framebuffer via drawarrays. Then I read from that texture in the next render call in the fragment shader and draw that to the quad (using 0-1 st coordinates).
I think I am doing so, but the size gets reassigned midprocess to the texture size of the bricks.
Is there anything else I can post here that would help?

teapotunzoomed.png teapotzoomed.png framebuffer2.png framebuffer1.png
haughty summit
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Check that you call glViewport() when changing where you render

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It sounds like you set it correctly when you render to texture, but forget to update viewport state when switching rendering to default (or some other) framebuffer.

novel shoal
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thanks a lot! I just found it by chance myself, but that was the answer. That was driving me crazy 😄
It looks super low res, because it would be this 512 texture scaled up to screen size right?

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I'm still wondering a bit that it is dependant on the texture of the teapot. I would've thought that it should be dependant on the size of the framebuffer texture, which should've been screensize and not 512. So "it works" but I'm still not sure about a few things...

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unsigned int framebuffer;
glGenFramebuffers(1, &framebuffer);
glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);
glGenTextures(1, &textureColorbuffer);
glBindTexture(GL_TEXTURE_2D, textureColorbuffer);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, screenWidth, screenHeight, 0, GL_RGB, GL_UNSIGNED_BYTE, NULL);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
unsigned int rbo;
glGenRenderbuffers(1, &rbo);
glBindRenderbuffer(GL_RENDERBUFFER, rbo);
glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH24_STENCIL8, screenWidth, screenHeight);       // use a single renderbuffer object for both a depth AND stencil buffer.
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT, GL_RENDERBUFFER, rbo); // now actually attach it
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, textureColorbuffer, 0);
GLenum drawBuffers[1] = {GL_COLOR_ATTACHMENT0};
glDrawBuffers(1, drawBuffers);

if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
    std::cout << "ERROR::FRAMEBUFFER:: Framebuffer is not complete!" << std::endl;
glBindFramebuffer(GL_FRAMEBUFFER, 0);

So why does it use the texture from here?

    glGenBuffers(1, &difTex);
    glActiveTexture(GL_TEXTURE0);
    glBindBuffer(GL_TEXTURE_2D, difTex);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, imgWidth, imgHeight, 0, GL_RGBA, GL_UNSIGNED_BYTE, &brickTexture[0]);
    glGenerateMipmap(GL_TEXTURE_2D);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR_MIPMAP_LINEAR);
novel shoal
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I mainly don't get where the 4th and 5th step happen:

image.png
haughty summit
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Looks like glBindBuffer() should be glBindTexture() instead