OpenGL GLSL Binding Sampler for Fragment Shader

Question

I am hoping to implement a shader on a 2D OpenGL application. My plan is to render a scene to a framebuffer object, and then render that framebuffer object to the screen using

Answer 1

There's indeed a problem with how you set the uniform value for the sampler:

gSampler = glGetUniformLocation(mProgramID, "gSampler");
glUniform1i(gSampler, GL_TEXTURE0);

The value you need to set for the uniform is the index of the texture unit, not the corresponding enum value. Since you are using texture unit 0 in this case, you need to replace the glUniform1i() call by:

glUniform1i(gSampler, 0);