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Diffstat (limited to 'nx-X11/extras/ogl-sample/main/doc/man/mangl/standard/frustum.gl')
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diff --git a/nx-X11/extras/ogl-sample/main/doc/man/mangl/standard/frustum.gl b/nx-X11/extras/ogl-sample/main/doc/man/mangl/standard/frustum.gl new file mode 100644 index 000000000..9688b9a0e --- /dev/null +++ b/nx-X11/extras/ogl-sample/main/doc/man/mangl/standard/frustum.gl @@ -0,0 +1,142 @@ +_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_ 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(Frustum,multiply the current matrix by a perspective matrix) +_names(Frustum) +.EQ +delim $$ +.EN +.SH PARAMETERS +_phead(_param1 _param2) +Specify the coordinates for the left and right vertical clipping planes. +_phead(_param3 _param4) +Specify the coordinates for the bottom and top horizontal clipping planes. +_phead(_param5 _param6) +Specify the distances to the near and far depth clipping planes. +Both distances must be positive. +.SH DESCRIPTION +_cmnd describes a perspective matrix that produces a perspective projection. +The current matrix (see _cmnd(MatrixMode)) is multiplied by this matrix +and the result replaces the current matrix, as if +_cmnd(MultMatrix) were called with the following matrix +as its argument: +.P +.sp 5 +.ce +.EQ +down 150 +{left [ ~~~ { +down 165 matrix { + ccol { {{2 ~ _eqnparam5} over {_eqnparam2 ~-~ _eqnparam1}} above 0 above 0 above 0 } + ccol { 0 above {{2 ~ _eqnparam5} over {_eqnparam4 ~-~ _eqnparam3}} ~ above 0 above 0 } + ccol { A ~~~~ above B ~~~~ above C ~~~~ above -1 ~~~~} + ccol { 0 above 0 above D above 0} +}} +~~~ right ]} +.EN +.sp +.ce +.EQ +down 130 +{A ~=~ {_eqnparam2 ~+~ _eqnparam1} over {_eqnparam2 ~-~ _eqnparam1}} +.EN +.sp +.ce +.EQ +down 130 +{B ~=~ {_eqnparam4 ~+~ _eqnparam3} over {_eqnparam4 ~-~ _eqnparam3}} +.EN +.sp +.ce +.EQ +down 130 +{C ~=~ -{{_eqnparam6 ~+~ _eqnparam5} over {_eqnparam6 ~-~ _eqnparam5}}} +.EN +.sp +.ce +.EQ +down 130 +{D ~=~ -^{{2 ~ _eqnparam6 ~ _eqnparam5} over {_eqnparam6 ~-~ _eqnparam5}}} +.EN +.sp 2 +.P +Typically, the matrix mode is _const(PROJECTION), and +(_param1, _param3, \-_param5) and (_param2, _param4, \-_param5) +specify the points on the near clipping plane that are mapped +to the lower left and upper right corners of the window, +assuming that the eye is located at (0, 0, 0). +\-_param6 specifies the location of the far clipping plane. +Both _param5 and _param6 must be positive. +.P +Use _cmnd(PushMatrix) and _cmnd(PopMatrix) to save and restore +the current matrix stack. +.SH NOTES +Depth buffer precision is affected by the values specified for +_param5 and _param6. +The greater the ratio of _param6 to _param5 is, +the less effective the depth buffer will be at distinguishing between +surfaces that are near each other. +If +.sp +.ce +$r ~=~ _eqnparam6 over _eqnparam5$ +.sp +roughly $log sub 2 (r)$ bits of depth buffer precision are lost. +Because $r$ approaches infinity as _param5 approaches 0, +_param5 must never be set to 0. +.SH ERRORS +_const(INVALID_VALUE) is generated if _param5 or _param6 is not +positive, or if _param1 = _param2, or _param3 = _param4. +.P +_const(INVALID_OPERATION) is generated if _cmnd +is executed between the execution of _cmnd(Begin) +and the corresponding execution of _cmnd(End). +.SH ASSOCIATED GETS +_cmnd(Get) with argument _const(MATRIX_MODE) +.br +_cmnd(Get) with argument _const(MODELVIEW_MATRIX) +.br +_cmnd(Get) with argument _const(PROJECTION_MATRIX) +.br +_cmnd(Get) with argument _const(TEXTURE_MATRIX) +.br +_cmnd(Get) with argument _const(COLOR_MATRIX) +.SH SEE ALSO +_cmnd(Ortho), +_cmnd(MatrixMode), +_cmnd(MultMatrix), +_cmnd(PushMatrix), +_cmnd(Viewport) |