#
# 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# Unpublished-- rights reserved under the copyright laws of the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 '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()