question: void initProgram ( ) { glUseProgram ( this . program ) ; viewMatrixUniform = glGetUniformLocation ( this . program , "viewMatrix" ) ; projMatrixUniform = glGetUniformLocation ( this . program , "projMatrix" ) ; viewportSizeUniform = glGetUniformLocation ( this . program , "viewportSize" ) ; glUseProgram ( 0 ) ; }
target:  Initialize the shader program.