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Diffstat (limited to 'xc/extras/ogl-sample/main/doc/man/manglu/standard/pickmatrix.gl')
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diff --git a/xc/extras/ogl-sample/main/doc/man/manglu/standard/pickmatrix.gl b/xc/extras/ogl-sample/main/doc/man/manglu/standard/pickmatrix.gl new file mode 100755 index 000000000..1f28b9e89 --- /dev/null +++ b/xc/extras/ogl-sample/main/doc/man/manglu/standard/pickmatrix.gl @@ -0,0 +1,105 @@ +_C_ License Applicability. Except to the extent portions of this file are +_C_ made subject to an alternative license as permitted in the SGI Free +_C_ Software License B, Version 1.1 (the "License"), the contents of this +_C_ file are subject only to the provisions of the License. You may not use +_C_ this file except in compliance with the License. You may obtain a copy +_C_ of the License at Silicon Graphics, Inc., attn: Legal Services, 1600 +_C_ Amphitheatre Parkway, Mountain View, CA 94043-1351, or at: +_C_ +_C_ http://oss.sgi.com/projects/FreeB +_C_ +_C_ Note that, as provided in the License, the Software is distributed on an +_C_ "AS IS" basis, with ALL EXPRESS AND IMPLIED WARRANTIES AND CONDITIONS +_C_ DISCLAIMED, INCLUDING, WITHOUT LIMITATION, ANY IMPLIED WARRANTIES AND +_C_ CONDITIONS OF MERCHANTABILITY, SATISFACTORY QUALITY, FITNESS FOR A +_C_ PARTICULAR PURPOSE, AND NON-INFRINGEMENT. +_C_ +_C_ Original Code. The Original Code is: OpenGL Sample Implementation, +_C_ Version 1.2.1, released January 26, 2000, developed by Silicon Graphics, +_C_ Inc. The Original Code is Copyright (c) 1991-2000 Silicon Graphics, Inc. +_C_ Copyright in any portions created by third parties is as indicated +_C_ elsewhere herein. All Rights Reserved. +_C_ +_C_ Additional Notice Provisions: The application programming interfaces +_C_ established by SGI in conjunction with the Original Code are The +_C_ OpenGL(R) Graphics System: A Specification (Version 1.2.1), released +_C_ April 1, 1999; The OpenGL(R) Graphics System Utility Library (Version +_C_ 1.3), released November 4, 1998; and OpenGL(R) Graphics with the X +_C_ Window System(R) (Version 1.3), released October 19, 1998. This software +_C_ was created using the OpenGL(R) version 1.2.1 Sample Implementation +_C_ published by SGI, but has not been independently verified as being +_C_ compliant with the OpenGL(R) version 1.2.1 Specification. +_C_ +_C_ $Date: 2001/03/19 17:45:27 $ $Revision: 1.1.1.1 $ +_C_ The first character in this file must be an '_'! +_C_ Anything on a line after _C_ is ignored +_define(_filters,eqn)_C_ +_C_ eqn is automatically replaced with neqn for nroff +_header(PickMatrix, define a picking region) +_names(PickMatrix) +.EQ +delim $$ +.EN +.SH PARAMETERS +_phead(_param1 _param2) +Specify the center of a picking region in window coordinates. +_phead(_param3 _param4) +Specify the width and height, respectively, of the picking region in window +coordinates. +_phead(_param5) +Specifies the current viewport (as from a _glcmnd(GetIntegerv) call). +.SH DESCRIPTION +_cmnd creates a projection matrix that can be used to restrict drawing +to a small region of the viewport. +This is typically useful to +determine what objects are being drawn near the cursor. +Use _cmnd to +restrict drawing to a small region around the cursor. +Then, +enter selection mode (with _glcmnd(RenderMode)) and rerender the scene. +All primitives that would have been drawn near +the cursor are identified and stored in the selection buffer. +.P +The matrix created by _cmnd is multiplied by the current matrix just +as if _glcmnd(MultMatrix) is called with the generated matrix. +To effectively use the generated pick matrix for picking, +first call _glcmnd(LoadIdentity) to load an identity matrix onto the +perspective matrix stack. +Then call _cmnd, +and finally, call a command (such as _cmnd(Perspective)) +to multiply the perspective matrix by the pick matrix. +.P +When using _cmnd to pick NURBS, be careful to turn off the NURBS +property +_gluconst(AUTO_LOAD_MATRIX). If _gluconst(AUTO_LOAD_MATRIX) is not +turned off, then any NURBS surface rendered is subdivided differently with +the pick matrix than the way it was subdivided without the pick matrix. +.bp +.SH EXAMPLE +When rendering a scene as follows: +.sp +.Ex +glMatrixMode(GL_PROJECTION); +glLoadIdentity(); +gluPerspective(...); +glMatrixMode(GL_MODELVIEW); +/* Draw the scene */ +.Ee +.sp +a portion of the viewport can be selected as a pick region like this: +.sp +.Ex +glMatrixMode(GL_PROJECTION); +glLoadIdentity(); +gluPickMatrix(x, y, width, height, viewport); +gluPerspective(...); +glMatrixMode(GL_MODELVIEW); +/* Draw the scene */ +.Ee +.SH SEE ALSO +_glcmnd(Get), +_glcmnd(LoadIndentity), +_glcmnd(MultMatrix), +_glcmnd(RenderMode), +_cmnd(Perspective) + |