glUseProgram doesn't change shader - opengl

Question

I am currently working on a application with (not yet implemented) post effects. So the 3D scene gets rendered in a buffer and then, another shader renders the buffer on the screen.
My problem is that the program uses my basic shader vor the 3d scene instead of the post effect shader in the second pass. Do you have an idea, what could be doing this?
My approach: I have a class which has two major functions:
- bindBuffer() sets the render Target to a buffer
- renderSSAO() renders the buffer to the screen and hopfuly one day will add an ambient occlusion effect. :)
BIND BUFFER FUNCTION
void SSAOShader::bindBuffer() {
glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);
glViewport(0,0,windowWidth,windowHeight);
}
RENDER FUNCTION
void SSAOShader::renderSSAO(GLuint currentShader) {
// set shader
glUseProgram(shader);
//draw on Screen
glBindFramebuffer(GL_FRAMEBUFFER, 0);
glViewport(0,0,windowWidth,windowHeight);
// clear screen
glClearColor(0.4, 0.4, 0.4, 1.0);
glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
// bind texture, pass to shader
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, renderTexture);
glUniform1i(textureID, 0);
glBindVertexArray(vertexarray);
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
glBindVertexArray(0);
glUseProgram(currentShader);
}
Render Loop (the functions are from the ssaoShader-object)
while (!glfwWindowShouldClose(mainWindow)) {
ssaoShader->bindBuffer();
// clear the screen
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
// draw cool stuff
ssaoShader->renderSSAO(programID);
// Swap buffers
glfwSwapBuffers(mainWindow);
glUseProgram(programID);
}
So basically, the render target gets set to my buffer with bindBuffer();, then I draw objects with my basic (phong etc) shader, and the renderSSAO function changes the target to my screen. This function also changes the shader to my post-effects shader and changes it back to whatever it was before. programID is the shader-GLuint.
I know that the problem is the used shader since the result of all is that I only have a black screen with a quad-gon in the world origin. I can also move around like normal.
CONSTRUCTOR
SSAOShader::SSAOShader(float windowWidth, float windowHeight, GLuint currentShader) {
this->windowWidth = windowWidth;
this->windowHeight = windowHeight;
//shader
shader = LoadShaders("Passthrough.vertexshader", "SSAO.fragmentshader");
glUseProgram(shader);
textureID = glGetUniformLocation(shader, "renderTexture");
int status;
glGetProgramiv(shader, GL_COMPILE_STATUS, &status);
std::cout << (status == GL_TRUE) << std::endl;
GLfloat planeVertices[] = {
-1, -1,
1, -1,
-1, 1,
1, 1
};
// create vertex array
glGenVertexArrays(1, &vertexarray);
glBindVertexArray(vertexarray);
// create "uv" (vertex) buffer
glGenBuffers(1, &vertexbuffer);
glBindBuffer(GL_ARRAY_BUFFER, vertexbuffer);
glBufferData(GL_ARRAY_BUFFER, sizeof(planeVertices), planeVertices, GL_STATIC_DRAW);
// add vertecies to as attributes
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 0, (void*)0);
glBindVertexArray(0);
// ---- set up framebuffer ----
glGenFramebuffers(1, &framebuffer);
glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);
glGenTextures(1, &renderTexture);
glBindTexture(GL_TEXTURE_2D, renderTexture);
glTexImage2D(GL_TEXTURE_2D, 0,GL_RGB, windowWidth, windowHeight, 0,GL_RGB, GL_UNSIGNED_BYTE, 0);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glGenRenderbuffers(1, &depthrenderbuffer);
glBindRenderbuffer(GL_RENDERBUFFER, depthrenderbuffer);
glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT, windowWidth, windowHeight);
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, depthrenderbuffer);
glFramebufferTexture(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, renderTexture, 0);
DrawBuffers[1] = GL_COLOR_ATTACHMENT0;
glDrawBuffers(1, DrawBuffers);
if(glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE){
exit(0); // bad luck
}
glBindFramebuffer(GL_FRAMEBUFFER, 0);
//glUseProgram(currentShader);
}
VS2012 Project
https://studi.f4.htw-berlin.de/~s0539750/SSAOTest.zip
For who ever is mad enough to look at my code. ;)

Answer 1

I found the problem.
glFramebufferTexture(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, renderTexture, 0);
DrawBuffers[1] = GL_COLOR_ATTACHMENT0;
glDrawBuffers(1, DrawBuffers);
This part in the constructor changed my GLuint shader;. I don't know why exactly but the reason was that DrawBuffers is a fixed array with size 1. Obviously, accessing DrawBuffers[1] isn't the best idea of the day. ;)
My guess would be that either DarBuffers[1] was used for my "shader" GLuint or the problem was that glDrawBuffers never realy attached GL_COLOR_ATTACHMENT0 to my framebuffer. What is the case?
Thanks for all the help by the way, It helped alot. :)