After some studying I found out how to render to a single texture using a color attachment. However, I'd like to create multiple textures using multiple attachments. Here is the code I use:
glGenFramebuffers(1, &myFBO);
glBindFramebuffer(GL_FRAMEBUFFER, myFBO);
glGenTextures(1, &RGBTexture);
glBindTexture(GL_TEXTURE_2D, RGBTexture);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, W_WIDTH/2, W_HEIGHT/2, 0, GL_RGB, GL_FLOAT, NULL);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, RGBTexture, 0);
glGenTextures(1, &normalMapTexture);
glBindTexture(GL_TEXTURE_2D, normalMapTexture);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, W_WIDTH/2, W_HEIGHT/2, 0, GL_RGB, GL_FLOAT, NULL);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT1, GL_TEXTURE_2D, normalMapTexture, 0);
unsigned int attachments[2] = {GL_COLOR_ATTACHMENT0, GL_COLOR_ATTACHMENT1 };
glDrawBuffers(2, attachments);
The fragment shader :
#version 330 core
layout(location=0) out vec3 fragment_color;
layout(location=1) out vec3 normal;
void main()
{
fragment_color = vec3(1, 1, 1);
normal=vec3(0,1,0);
}
Just for testing, I render a white and a green texture. However, when I render them on a quad later, they are empty.
When using only one attachment, I avoid the "location" commands in the fragment shader. I just declare an out vec3 and the single texture is generated just fine. I render it on a quad and it is indeed ok. So there has to be something wrong with my FBO or the fragment shader.
Note that I have also bound a depth component ( not shown above ) which works properly. I mention it in case it matters.
Update-Solution
If I define the outputs in the fragment shader as vec4 everything works just fine. WHY?
question from:
https://stackoverflow.com/questions/65872762/how-can-i-render-to-multiple-attachments-of-a-fbo 
