Introduction - If you have any usage issues, please Google them yourself
projection matrix storage to a one-dimensional arrays, and functions glFrustum. glOrtho, gluPerspective same as the corresponding parameters, and to compare the current projection matrix, and the use of design as a function of the results. On the screen two output matrix and compared. Use glGetFloatv (GL_PROJECTION_MATRIX. ...) access to current projection matrix.