#
# Copyright (c) 1993-1997, Silicon Graphics, Inc.
# ALL RIGHTS RESERVED
# Permission to use, copy, modify, and distribute this software for
# any purpose and without fee is hereby granted, provided that the above
# copyright notice appear in all copies and that both the copyright notice
# and this permission notice appear in supporting documentation, and that
# the name of Silicon Graphics, Inc. not be used in advertising
# or publicity pertaining to distribution of the software without specific,
# written prior permission.
#
# THE MATERIAL EMBODIED ON THIS SOFTWARE IS PROVIDED TO YOU "AS-IS"
# AND WITHOUT WARRANTY OF ANY KIND, EXPRESS, IMPLIED OR OTHERWISE,
# INCLUDING WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY OR
# FITNESS FOR A PARTICULAR PURPOSE.  IN NO EVENT SHALL SILICON
# GRAPHICS, INC.  BE LIABLE TO YOU OR ANYONE ELSE FOR ANY DIRECT,
# SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY
# KIND, OR ANY DAMAGES WHATSOEVER, INCLUDING WITHOUT LIMITATION,
# LOSS OF PROFIT, LOSS OF USE, SAVINGS OR REVENUE, OR THE CLAIMS OF
# THIRD PARTIES, WHETHER OR NOT SILICON GRAPHICS, INC.  HAS BEEN
# ADVISED OF THE POSSIBILITY OF SUCH LOSS, HOWEVER CAUSED AND ON
# ANY THEORY OF LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE
# POSSESSION, USE OR PERFORMANCE OF THIS SOFTWARE.
#
# US Government Users Restricted Rights
# Use, duplication, or disclosure by the Government is subject to
# restrictions set forth in FAR 52.227.19(c)(2) or subparagraph
# (c)(1)(ii) of the Rights in Technical Data and Computer Software
# clause at DFARS 252.227-7013 and/or in similar or successor
# clauses in the FAR or the DOD or NASA FAR Supplement.
# Unpublished-- rights reserved under the copyright laws of the
# United States.  Contractor/manufacturer is Silicon Graphics,
# Inc., 2011 N.  Shoreline Blvd., Mountain View, CA 94039-7311.
#
# OpenGL(R) is a registered trademark of Silicon Graphics, Inc.
#
# aargb.c
# This program draws shows how to draw anti-aliased lines. It draws
# two diagonal lines to form an X when 'r' is typed in the window,
# the lines are rotated in opposite directions.
require 'opengl'
require 'glu'
require 'glut'
require 'mathn'
include Gl,Glu,Glut

$rotAngle = 0.0

# Initialize antialiasing for RGBA mode, including alpha
# blending, hint, and line width.  Print out implementation
# specific info on line width granularity and width.
def init
  glEnable(GL_LINE_SMOOTH)
  glEnable(GL_BLEND)
  glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA)
  glHint(GL_LINE_SMOOTH_HINT, GL_DONT_CARE)
  glLineWidth(1.5)
  glClearColor(0.0, 0.0, 0.0, 0.0)
end

# Draw 2 diagonal lines to form an X
display = Proc.new do
  glClear(GL_COLOR_BUFFER_BIT)

  glColor(0.0, 1.0, 0.0)
  glPushMatrix()
  glRotate(-$rotAngle, 0.0, 0.0, 0.1)
  glBegin(GL_LINES)
  glVertex(-0.5, 0.5)
  glVertex(0.5, -0.5)
  glEnd()
  glPopMatrix()

  glColor(0.0, 0.0, 1.0)
  glPushMatrix()
  glRotate($rotAngle, 0.0, 0.0, 0.1)
  glBegin(GL_LINES)
  glVertex(0.5, 0.5)
  glVertex(-0.5, -0.5)
  glEnd()
  glPopMatrix()
  glutSwapBuffers()
end

reshape = Proc.new do |w, h|
  glViewport(0, 0, w, h)
  glMatrixMode(GL_PROJECTION)
  glLoadIdentity()
  if (w <= h)
    gluOrtho2D(-1.0, 1.0, -1.0*h/w, 1.0*h/w)
  else
    gluOrtho2D(-1.0*w/h, 1.0*w/h, -1.0, 1.0)
  end
  glMatrixMode(GL_MODELVIEW)
  glLoadIdentity()
end

keyboard = Proc.new do |key, x, y|
  case (key)
    when ?r,?R
      $rotAngle = $rotAngle + 20.0
      $rotAngle = 0.0 if ($rotAngle >= 360.0)
      glutPostRedisplay()
    when ?\e  # Escape Key
      exit(0)
  end
end

# Main Loop
# Open window with initial window size, title bar,
# RGBA display mode, and handle input events.
glutInit
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB)
glutInitWindowSize(500, 500)
glutInitWindowPosition(100, 100)
glutCreateWindow($0)
init()
glutReshapeFunc(reshape)
glutKeyboardFunc(keyboard)
glutDisplayFunc(display)
glutMainLoop()
