#
# Copyright (c) Mark J. Kilgard, 1994.
#
# (c) Copyright 1993, 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# Unpublished-- rights reserved under the copyright laws of the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(TM) is a trademark of Silicon Graphics, Inc.
#
# dof.c
# This program demonstrates use of the accumulation buffer to
# create an out-of-focus depth-of-field effect.  The teapots
# are drawn several times into the accumulation buffer.  The
# viewing volume is jittered, except at the focal point, where
# the viewing volume is at the same position, each time.  In
# this case, the gold teapot remains in focus.
require 'opengl'
require 'glu'
require 'glut'
require_relative 'jitter'
include Gl,Glu,Glut

# accFrustum()
# The first 6 arguments are identical to the glFrustum() call.
#
# pixdx and pixdy are anti-alias jitter in pixels.
# Set both equal to 0.0 for no anti-alias jitter.
# eyedx and eyedy are depth-of field jitter in pixels.
# Set both equal to 0.0 for no depth of field effects.
#
# focus is distance from eye to plane in focus.
# focus must be greater than, but not equal to 0.0.
#
# Note that accFrustum() calls glTranslatef().  You will
# probably want to insure that your ModelView matrix has been
# initialized to identity before calling accFrustum().
def accFrustum(left, right, bottom, top, nnear, ffar, pixdx, pixdy, eyedx, eyedy, focus)
  viewport = glGetDoublev(GL_VIEWPORT)

  xwsize = right - left
  ywsize = top - bottom

  dx = -(pixdx*xwsize/viewport[2] + eyedx*nnear/focus)
  dy = -(pixdy*ywsize/viewport[3] + eyedy*nnear/focus)

  glMatrixMode(GL_PROJECTION)
  glLoadIdentity()
  glFrustum(left + dx, right + dx, bottom + dy, top + dy, nnear, ffar)
  glMatrixMode(GL_MODELVIEW)
  glLoadIdentity()
  glTranslate(-eyedx, -eyedy, 0.0)
end

# accPerspective()
#
# The first 4 arguments are identical to the gluPerspective() call.
# pixdx and pixdy are anti-alias jitter in pixels.
# Set both equal to 0.0 for no anti-alias jitter.
# eyedx and eyedy are depth-of field jitter in pixels.
# Set both equal to 0.0 for no depth of field effects.
#
# focus is distance from eye to plane in focus.
# focus must be greater than, but not equal to 0.0.
#
# Note that accPerspective() calls accFrustum().
def  accPerspective(fovy, aspect, nnear, ffar, pixdx, pixdy, eyedx, eyedy, focus)
  fov2 = ((fovy*Math::PI) / 180.0) / 2.0

  top = nnear / (Math::cos(fov2) / Math::sin(fov2))
  bottom = -top

  right = top * aspect
  left = -right

  accFrustum(left, right, bottom, top, nnear, ffar, pixdx, pixdy, eyedx, eyedy, focus)
end


def myinit
  ambient = [ 0.0, 0.0, 0.0, 1.0 ]
  diffuse = [ 1.0, 1.0, 1.0, 1.0 ]
  position = [ 0.0, 3.0, 3.0, 0.0 ]

  lmodel_ambient = [ 0.2, 0.2, 0.2, 1.0 ]
  local_view = [ 0.0 ]

  glEnable(GL_DEPTH_TEST)
  glDepthFunc(GL_LESS)

  glLight(GL_LIGHT0, GL_AMBIENT, ambient)
  glLight(GL_LIGHT0, GL_DIFFUSE, diffuse)
  glLight(GL_LIGHT0, GL_POSITION, position)

  glLightModel(GL_LIGHT_MODEL_AMBIENT, lmodel_ambient)
  glLightModel(GL_LIGHT_MODEL_LOCAL_VIEWER, local_view)

  glFrontFace(GL_CW)
  glEnable(GL_LIGHTING)
  glEnable(GL_LIGHT0)
  glEnable(GL_AUTO_NORMAL)
  glEnable(GL_NORMALIZE)

  glMatrixMode(GL_MODELVIEW)
  glLoadIdentity()

  glClearColor(0.0, 0.0, 0.0, 0.0)
  glClearAccum(0.0, 0.0, 0.0, 0.0)
end

def renderTeapot (x, y, z, ambr, ambg, ambb, difr, difg, difb, specr, specg, specb, shine)
  glPushMatrix()
  glTranslate(x, y, z)
  mat = []
  mat[0] = ambr; mat[1] = ambg; mat[2] = ambb; mat[3] = 1.0
  glMaterial(GL_FRONT, GL_AMBIENT, mat)
  mat[0] = difr; mat[1] = difg; mat[2] = difb
  glMaterial(GL_FRONT, GL_DIFFUSE, mat)
  mat[0] = specr; mat[1] = specg; mat[2] = specb
  glMaterial(GL_FRONT, GL_SPECULAR, mat)
  glMaterial(GL_FRONT, GL_SHININESS, shine*128.0)
  glutSolidTeapot(0.5)
  glPopMatrix()
end

#  display() draws 5 teapots into the accumulation buffer
#  several times each time with a jittered perspective.
#  The focal point is at z = 5.0, so the gold teapot will
#  stay in focus.  The amount of jitter is adjusted by the
#  magnitude of the accPerspective() jitter in this example, 0.33.
#  In this example, the teapots are drawn 8 times.  See jitter.rb
display = proc do
  viewport = glGetDoublev(GL_VIEWPORT)
  glClear(GL_ACCUM_BUFFER_BIT)

  for jitter in 0...8
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
    accPerspective(45.0,
    viewport[2]/ viewport[3],
    1.0, 15.0, 0.0, 0.0,
    0.33*$j8[jitter][0], 0.33*$j8[jitter][1], 5.0)
    # ruby, gold, silver, emerald, and cyan teapots
    renderTeapot(-1.1, -0.5, -4.5, 0.1745, 0.01175, 0.01175, 0.61424, 0.04136, 0.04136, 0.727811, 0.626959, 0.626959, 0.6)
    renderTeapot(-0.5, -0.5, -5.0, 0.24725, 0.1995, 0.0745, 0.75164, 0.60648, 0.22648, 0.628281, 0.555802, 0.366065, 0.4)
    renderTeapot(0.2, -0.5, -5.5, 0.19225, 0.19225, 0.19225, 0.50754, 0.50754, 0.50754, 0.508273, 0.508273, 0.508273, 0.4)
    renderTeapot(1.0, -0.5, -6.0, 0.0215, 0.1745, 0.0215, 0.07568, 0.61424, 0.07568, 0.633, 0.727811, 0.633, 0.6)
    renderTeapot(1.8, -0.5, -6.5, 0.0, 0.1, 0.06, 0.0, 0.50980392, 0.50980392, 0.50196078, 0.50196078, 0.50196078, 0.25)
    glAccum(GL_ACCUM, 0.125)
  end

  glAccum(GL_RETURN, 1.0)
  glutSwapBuffers()
end

myReshape = proc do |w, h|
  glViewport(0, 0, w, h)
end

keyboard = proc do |key, x, y|
  case (key)
    when ?\e
    exit(0)
  end
end

# Main Loop
# Open window with initial window size, title bar,
# RGBA display mode, depth buffer, and handle input events.
glutInit()
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_ACCUM | GLUT_DEPTH)
glutInitWindowSize(500, 500)
glutInitWindowPosition(100, 100)
glutCreateWindow()
myinit()
glutReshapeFunc(myReshape)
glutDisplayFunc(display)
glutKeyboardFunc(keyboard)
glutMainLoop()
