Using two different shaders for two different VAOS - opengl

Question

I have two seperate VAO objects that render in a while loop as such. Each one needs to be drawn with a different shader program. I can get them both rendering individually, but together only the skybox renders.
do{
// Clear the screen
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
// Access the active camera
glm::mat4 ViewMatrix;
if(worldCamMode)
{
worldCam->update();
ViewMatrix = worldCamParent->getViewMtx();
}
else
{
playerCam->update();
ViewMatrix = playerCamParent->getViewMtx();
}
// Retrieve the projection and model matrices
glm::mat4 ProjectionMatrix = getProjectionMatrix();
glm::mat4 ModelMatrix = glm::mat4(1.0f);
glm::mat4 MVP = ProjectionMatrix * ViewMatrix * ModelMatrix;
glm::mat4 MVPX = ProjectionMatrix * ViewMatrix;
// Render the skybox first
glm::mat4 view = glm::mat4(glm::mat3(ViewMatrix));
cloudySkybox->render(cubemapTexture, view, ProjectionMatrix, skyboxProgramID);
int viewHandle = glGetUniformLocation(lampID, "view");
if (viewHandle == -1) {
std::cout << "Uniform: view is not an active uniform label\n";
}
glUniformMatrix4fv( viewHandle, 1, false, &MVPX[0][0]);
glUseProgram(lampID);
testObj.render(lampID);
// Swap buffers
glfwSwapBuffers(window);
glfwPollEvents();
} // Check if the ESC key was pressed or the window was closed
while( glfwGetKey(window, GLFW_KEY_ESCAPE ) != GLFW_PRESS &&
glfwWindowShouldClose(window) == 0 );
The first object to render is cloudySkybox. This is the only thing that renders and testObj does not r ender unless I comment out the cloudySkybox line. I have narrowed it down to see what breaks the testObj. testObj renders fine until I use the line glUseProgram(shaderID); and then it stops rendering. Does anyone have any clue why this might be? The testObj.render() function has the same format with glUseProgram(differentShader)
void skybox::render(unsigned int cubemapTexture, glm::mat4 view, glm::mat4 projection, int shaderID)
{
glUseProgram(shaderID);
//glDepthMask(GL_FALSE);
//int viewUniformHandle = glGetUniformLocation(shaderID, "view");
//if (viewUniformHandle == -1)
// exit(1);
//glUniformMatrix4fv( viewUniformHandle, 1, false, glm::value_ptr(view) );
//int projectionUniformHandle = glGetUniformLocation(shaderID, "projection");
//if (projectionUniformHandle == -1)
// exit(1);
//glUniformMatrix4fv( projectionUniformHandle, 1, false, glm::value_ptr(projection) );
//glBindVertexArray(skyboxVAO);
//glBindTexture(GL_TEXTURE_CUBE_MAP, cubemapTexture);
//glDrawArrays(GL_TRIANGLES, 0, 36);
//glDepthMask(GL_TRUE);
//glBindVertexArray(0);
//glFlush();
}
void Model::render(int programID)
{
glUseProgram(programID);
int modelUniformHandle = glGetUniformLocation(programID, "model");
if (modelUniformHandle == -1)
exit(1);
glm::mat4 model;
for (int i = 0; i < VAOs.size(); i++) {
glUseProgram(programID);
glBindVertexArray(VAOs[i]);
model = glm::mat4(1.0f);
glBindTexture(GL_TEXTURE_2D, TexID[this->shape[i].mesh.material_ids[i]]);
glUniformMatrix4fv(modelUniformHandle, 1, false, glm::value_ptr(model));
glDrawElements(GL_TRIANGLES, this->shape[i].mesh.indices.size(), GL_UNSIGNED_INT, 0);
glBindVertexArray(0);
glFlush();
}
}

Answer 1

glUniform operates on the program object that was made part of current state by calling glUseProgram. Set program glUseProgram(lampID) before calling glUniformMatrix4fv