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#
# 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# Unpublished-- rights reserved under the copyright laws of the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.
#
# texgen.c
# This program draws a texture mapped teapot with
# automatically generated texture coordinates. The
# texture is rendered as stripes on the teapot.
# Initially, the object is drawn with texture coordinates
# based upon the object coordinates of the vertex
# and distance from the plane x = 0. Pressing the 'e'
# key changes the coordinate generation to eye coordinates
# of the vertex. Pressing the 'o' key switches it back
# to the object coordinates. Pressing the 's' key
# changes the plane to a slanted one (x + y + z = 0).
# Pressing the 'x' key switches it back to x = 0.
require 'opengl'
require 'mathn'
include Gl,Glu,Glut
StripeImageWidth = 32
$stripeImage = []
$texName
def makeStripeImage
for j in (0..StripeImageWidth-1)
$stripeImage[4*j] = if (j<=4) then 255 else 0 end
$stripeImage[4*j+1] = if (j>4) then 255 else 0 end
$stripeImage[4*j+2] = 0
$stripeImage[4*j+3] = 255
end
end
# planes for texture coordinate generation
$xequalzero = [1.0, 0.0, 0.0, 0.0]
$slanted = [1.0, 1.0, 1.0, 0.0]
$currentCoeff = nil
$currentPlane = nil
$currentGenMode = nil
def init
glClearColor(0.0, 0.0, 0.0, 0.0)
glEnable(GL_DEPTH_TEST)
glShadeModel(GL_SMOOTH)
makeStripeImage()
glPixelStorei(GL_UNPACK_ALIGNMENT, 1)
$texName = glGenTextures(1)
glBindTexture(GL_TEXTURE_2D, $texName[0])
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR)
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, StripeImageWidth, 1, 0,
GL_RGBA, GL_UNSIGNED_BYTE, $stripeImage.pack("C*"))
glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE)
$currentCoeff = $xequalzero
$currentGenMode = GL_OBJECT_LINEAR
$currentPlane = GL_OBJECT_PLANE
glTexGen(GL_S, GL_TEXTURE_GEN_MODE, $currentGenMode)
glTexGen(GL_S, $currentPlane, $currentCoeff)
glEnable(GL_TEXTURE_GEN_S)
glEnable(GL_TEXTURE_2D)
glEnable(GL_CULL_FACE)
glEnable(GL_LIGHTING)
glEnable(GL_LIGHT0)
glEnable(GL_AUTO_NORMAL)
glEnable(GL_NORMALIZE)
glFrontFace(GL_CW)
glCullFace(GL_BACK)
glMaterial(GL_FRONT, GL_SHININESS, 64.0)
end
display = Proc.new do
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
glPushMatrix()
glRotate(45.0, 0.0, 0.0, 1.0)
glBindTexture(GL_TEXTURE_2D, $texName[0])
glutSolidTeapot(2.0)
glPopMatrix()
glutSwapBuffers()
end
reshape = Proc.new do |w, h|
glViewport(0, 0, w, h)
glMatrixMode(GL_PROJECTION)
glLoadIdentity()
if (w <= h)
glOrtho(-3.5, 3.5, -3.5*h/w,3.5*h/w, -3.5, 3.5)
else
glOrtho(-3.5*w/h, 3.5*w/h, -3.5, 3.5, -3.5, 3.5)
end
glMatrixMode(GL_MODELVIEW)
glLoadIdentity()
end
keyboard = Proc.new do |key, x, y|
case (key)
when ?e,?E
$currentGenMode = GL_EYE_LINEAR
$currentPlane = GL_EYE_PLANE
glTexGen(GL_S, GL_TEXTURE_GEN_MODE, $currentGenMode)
glTexGen(GL_S, $currentPlane, $currentCoeff)
glutPostRedisplay()
when ?o, ?O
$currentGenMode = GL_OBJECT_LINEAR
$currentPlane = GL_OBJECT_PLANE
glTexGen(GL_S, GL_TEXTURE_GEN_MODE, $currentGenMode)
glTexGen(GL_S, $currentPlane, $currentCoeff)
glutPostRedisplay()
when ?s,?S
$currentCoeff = $slanted
glTexGen(GL_S, $currentPlane, $currentCoeff)
glutPostRedisplay()
when ?x,?X
$currentCoeff = $xequalzero
glTexGen(GL_S, $currentPlane, $currentCoeff)
glutPostRedisplay()
when ?\e
exit(0)
end
end
# main
glutInit
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH)
glutInitWindowSize(500, 500)
glutInitWindowPosition(100, 100)
glutCreateWindow($0)
init()
glutDisplayFunc(display)
glutReshapeFunc(reshape)
glutKeyboardFunc(keyboard)
glutMainLoop()
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