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http://www.dolfyn.net/dolfyn/f03gl_en.html

いわゆる Green Book からのサンプルのつづき。

program fgl02

  use opengl_gl
  use opengl_glu
  use opengl_glut

  external display
  
  integer(kind=GLint) :: iwin
  real(kind=GLdouble) :: window(4) = (/ 0.0, 200.0, 0.0, 100.0 /)
  
  call glutInit
  call glutInitDisplayMode(GLUT_SINGLE + GLUT_RGB )
  call glutInitWindowPosition( 50, 100)
  call glutInitWindowSize( 200, 100)
  iwin = glutCreateWindow("fgl02"//char(0))
  
  call glClearColor( 1.0, 1.0, 1.0, 0.0)
  call glMatrixMode( GL_PROJECTION )
  call gluOrtho2D( window(1), window(2), window(3), window(4) )
  
  call glutDisplayFunc( display )
  
  call glutMainLoop()
  
end program fgl02

subroutine display 

use opengl_gl

call glClear( GL_COLOR_BUFFER_BIT )

call glColor3f( 1.0, 0.0, 0.0)
call glBegin( GL_LINES )

call glVertex2i( 180, 20)
call glVertex2i(  20, 80)

call glEnd()

call glFlush()

end subroutine display

DOS窓は略