redbook_alpha.py (revision 351)


#! /usr/bin/env python
"""Demonstration of effect of rendering order on blended polys

/*
 * Copyright (c) 1993-1999, 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 * Unpublished-- rights reserved under the copyright laws of the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.
 */

/*
 *  alpha.c
 *  This program draws several overlapping filled polygons
 *  to demonstrate the effect order has on alpha blending results.
 *  Use the 't' key to toggle the order of drawing polygons.
 */
"""
from OpenGLContext import testingcontext
BaseContext = testingcontext.getInteractive()
from OpenGLContext import context
from OpenGL.GL import *
from OpenGLContext.arrays import array
import string


class TestContext( BaseContext ):
	"""Red Book alpha.c
	Demonstrates the effects of alpha blending
	Copyright (c) 1993-1999, Silicon Graphics, Inc. ALL RIGHTS RESERVED 
	"""
	initialPosition = (0,0,2)
	def OnInit( self ):
		self.leftFirst = 1
		self.addEventHandler( 'keypress', name='f', function = self.OnSwitch )
		print 'Press "f" to switch polygon order'
	def OnSwitch( self, event ):
		"""Switch order of triangles"""
		self.leftFirst = not self.leftFirst
		self.triggerRedraw(1)
	def SetupDisplay( self, mode = None ):
		"""Setup display for display for the given mode"""
		### NOTE:
		### required because the context enables by default!
		glDisable(GL_DEPTH_TEST);
	def Render( self, mode = 0):
		BaseContext.Render( self, mode )
		glEnable (GL_BLEND);
		glDisable( GL_LIGHTING )
		glBlendFunc (GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
		glShadeModel (GL_FLAT);

		if self.leftFirst:
			self.left();
			self.right();
		else:
			self.right();
			self.left();


	def left( self ):
		"""draw yellow triangle on LHS of screen"""
		glBegin (GL_TRIANGLES);
		glColor4f(1.0, 1.0, 0.0, 0.5);
		glVertex3f(0.1, 0.9, 0.0);
		glVertex3f(0.1, 0.1, 0.0);
		glVertex3f(0.7, 0.5, 0.0);
		glEnd();
	def right( self ):
		"""draw cyan triangle on RHS of screen"""
		glBegin (GL_TRIANGLES);
		glColor4f(0.0, 1.0, 1.0, 0.5);
		glVertex3f(0.9, 0.9, 0.0); 
		glVertex3f(0.3, 0.5, 0.0); 
		glVertex3f(0.9, 0.1, 0.0); 
		glEnd();


if __name__ == "__main__":
	TestContext.ContextMainLoop()



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Line	Revision	Contents
1	1	#! /usr/bin/env python
2		"""Demonstration of effect of rendering order on blended polys
3
4		/*
5		* Copyright (c) 1993-1999, Silicon Graphics, Inc.
6		* ALL RIGHTS RESERVED
7		* Permission to use, copy, modify, and distribute this software for
8		* any purpose and without fee is hereby granted, provided that the above
9		* copyright notice appear in all copies and that both the copyright notice
10		* and this permission notice appear in supporting documentation, and that
11		* the name of Silicon Graphics, Inc. not be used in advertising
12		* or publicity pertaining to distribution of the software without specific,
13		* written prior permission.
14		*
15		* THE MATERIAL EMBODIED ON THIS SOFTWARE IS PROVIDED TO YOU "AS-IS"
16		* AND WITHOUT WARRANTY OF ANY KIND, EXPRESS, IMPLIED OR OTHERWISE,
17		* INCLUDING WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY OR
18		* FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL SILICON
19		* GRAPHICS, INC. BE LIABLE TO YOU OR ANYONE ELSE FOR ANY DIRECT,
20		* SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY
21		* KIND, OR ANY DAMAGES WHATSOEVER, INCLUDING WITHOUT LIMITATION,
22		* LOSS OF PROFIT, LOSS OF USE, SAVINGS OR REVENUE, OR THE CLAIMS OF
23		* THIRD PARTIES, WHETHER OR NOT SILICON GRAPHICS, INC. HAS BEEN
24		* ADVISED OF THE POSSIBILITY OF SUCH LOSS, HOWEVER CAUSED AND ON
25		* ANY THEORY OF LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE
26		* POSSESSION, USE OR PERFORMANCE OF THIS SOFTWARE.
27		*
28		* US Government Users Restricted Rights
29		* Use, duplication, or disclosure by the Government is subject to
30		* restrictions set forth in FAR 52.227.19(c)(2) or subparagraph
31		* (c)(1)(ii) of the Rights in Technical Data and Computer Software
32		* clause at DFARS 252.227-7013 and/or in similar or successor
33		* clauses in the FAR or the DOD or NASA FAR Supplement.
34		* Unpublished-- rights reserved under the copyright laws of the
35		* United States. Contractor/manufacturer is Silicon Graphics,
36		* Inc., 2011 N. Shoreline Blvd., Mountain View, CA 94039-7311.
37		*
38		* OpenGL(R) is a registered trademark of Silicon Graphics, Inc.
39		*/
40
41		/*
42		* alpha.c
43		* This program draws several overlapping filled polygons
44		* to demonstrate the effect order has on alpha blending results.
45		* Use the 't' key to toggle the order of drawing polygons.
46		*/
47		"""
48		from OpenGLContext import testingcontext
49	296	BaseContext = testingcontext.getInteractive()
50	1	from OpenGLContext import context
51		from OpenGL.GL import *
52		from OpenGLContext.arrays import array
53		import string
54
55
56		class TestContext( BaseContext ):
57		"""Red Book alpha.c
58		Demonstrates the effects of alpha blending
59		Copyright (c) 1993-1999, Silicon Graphics, Inc. ALL RIGHTS RESERVED
60		"""
61		initialPosition = (0,0,2)
62		def OnInit( self ):
63		self.leftFirst = 1
64		self.addEventHandler( 'keypress', name='f', function = self.OnSwitch )
65		print 'Press "f" to switch polygon order'
66		def OnSwitch( self, event ):
67		"""Switch order of triangles"""
68		self.leftFirst = not self.leftFirst
69		self.triggerRedraw(1)
70		def SetupDisplay( self, mode = None ):
71		"""Setup display for display for the given mode"""
72		### NOTE:
73		### required because the context enables by default!
74		glDisable(GL_DEPTH_TEST);
75		def Render( self, mode = 0):
76		BaseContext.Render( self, mode )
77		glEnable (GL_BLEND);
78		glDisable( GL_LIGHTING )
79		glBlendFunc (GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
80		glShadeModel (GL_FLAT);
81
82		if self.leftFirst:
83		self.left();
84		self.right();
85		else:
86		self.right();
87		self.left();
88
89
90		def left( self ):
91		"""draw yellow triangle on LHS of screen"""
92		glBegin (GL_TRIANGLES);
93		glColor4f(1.0, 1.0, 0.0, 0.5);
94		glVertex3f(0.1, 0.9, 0.0);
95		glVertex3f(0.1, 0.1, 0.0);
96		glVertex3f(0.7, 0.5, 0.0);
97		glEnd();
98		def right( self ):
99		"""draw cyan triangle on RHS of screen"""
100		glBegin (GL_TRIANGLES);
101		glColor4f(0.0, 1.0, 1.0, 0.5);
102		glVertex3f(0.9, 0.9, 0.0);
103		glVertex3f(0.3, 0.5, 0.0);
104		glVertex3f(0.9, 0.1, 0.0);
105		glEnd();
106
107
108		if __name__ == "__main__":
109	296	TestContext.ContextMainLoop()
110	1
111