4. Identity Matrix

• glm::mat4 constructor that takes only a single value constructs a diagonal matrix:

  
      glm::mat4 m4( 1.0f ); // construct identity matrix
  
  

• The matrix has all zeros except for 1.0f set along the diagonal from the upper-left to the lower-right.

• The default constructor glm::mat4() creates diagonal matrix with 1.0f diagonal, that is, the identity matrix:

  
      glm::mat4 m4; // construct identity matrix