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Diffstat (limited to 'nx-X11/extras/ogl-sample/main/doc/man/manglu/standard/tessvertex.gl')
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diff --git a/nx-X11/extras/ogl-sample/main/doc/man/manglu/standard/tessvertex.gl b/nx-X11/extras/ogl-sample/main/doc/man/manglu/standard/tessvertex.gl new file mode 100644 index 000000000..10beb5cbb --- /dev/null +++ b/nx-X11/extras/ogl-sample/main/doc/man/manglu/standard/tessvertex.gl @@ -0,0 +1,112 @@ +_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: 2004/03/14 08:29:09 $ $Revision: 1.1.1.4 $ +_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(TessVertex, specify a vertex on a polygon) +_names(TessVertex) +.EQ +delim $$ +.EN +.SH PARAMETERS +_phead(_param1) +Specifies the tessellation object (created with _cmnd(NewTess)). +_phead(_param2) +Specifies the location of the vertex. +_phead(_param3) +Specifies an opaque pointer passed back to the program with the vertex callback +(as specified by _cmnd(TessCallback)). +.SH DESCRIPTION +_cmnd describes a vertex on a polygon that the program defines. Successive +_cmnd calls describe a closed contour. For example, +to describe a quadrilateral _cmnd should be called four times. +_cmnd can only be called between _cmnd(TessBeginContour) and +_cmnd(TessEndContour). +.P +_param3 normally points to a structure containing the vertex +location, as well as other per-vertex attributes such as color and normal. +This pointer is passed back to the user through the _gluconst(TESS_VERTEX) +or _gluconst(TESS_VERTEX_DATA) callback after tessellation +(see the _cmnd(TessCallback) reference page). +.SH EXAMPLE +A quadrilateral with a triangular hole in it can be described as follows: +.sp +.Ex +gluTessBeginPolygon(tobj, NULL); + gluTessBeginContour(tobj); + gluTessVertex(tobj, v1, v1); + gluTessVertex(tobj, v2, v2); + gluTessVertex(tobj, v3, v3); + gluTessVertex(tobj, v4, v4); + gluTessEndContour(tobj); + gluTessBeginContour(tobj); + gluTessVertex(tobj, v5, v5); + gluTessVertex(tobj, v6, v6); + gluTessVertex(tobj, v7, v7); + gluTessEndContour(tobj); +gluTessEndPolygon(tobj); +.Ee +.sp +.SH NOTES +It is a common error to use a local variable for _param2 or _param3 and store +values into it as part of a loop. +For example: +.Ex +for (i = 0; i < NVERTICES; ++i) { + GLdouble data[3]; + data[0] = vertex[i][0]; + data[1] = vertex[i][1]; + data[2] = vertex[i][2]; + gluTessVertex(tobj, data, data); + } +.Ee +.P +This doesn't work. +Because the pointers specified by _param2 and _param3 might not be +dereferenced until _cmnd(TessEndPolygon) is executed, +all the vertex coordinates but the very last set could be overwritten +before tessellation begins. +.P +Two common symptoms of this problem are consists of a single point +(when a local variable is used for _param3) and a +_gluconst(TESS_NEED_COMBINE_CALLBACK) error (when a local variable is +used for _param2). +.SH SEE ALSO +_cmnd(TessBeginPolygon), _cmnd(NewTess), _cmnd(TessBeginContour), +_cmnd(TessCallback), +_cmnd(TessProperty), _cmnd(TessNormal), +_cmnd(TessEndPolygon) + + |