Passing uniform 4x4 matrix to vertex shader program

Question

I am trying to learn OpenGL and following this: http://www.opengl-tutorial.org/beginners-tutorials/tutorial-3-matrices/

Up until the point where they started passing mat

Answer 1

Consider using value_ptr rather then &MVP[0][0]

glUniformMatrix4fv(MatrixID, 1, GL_FALSE, glm::value_ptr(MVP));

genType::value_type const* glm::value_ptr (genType const & vec)

Return the constant address to the data of the input parameter

Answer 2

glUniform*() calls set values for the current program. You need to call glUseProgram() before the glUniform*() call. In this example:

glUseProgram(programID);
glUniformMatrix4fv(MatrixID, 1, GL_FALSE, &MVP[0][0]);