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diff --git a/nx-X11/extras/ogl-sample/main/doc/man/mangl/standard/fog.gl b/nx-X11/extras/ogl-sample/main/doc/man/mangl/standard/fog.gl new file mode 100644 index 000000000..a6f4ff44e --- /dev/null +++ b/nx-X11/extras/ogl-sample/main/doc/man/mangl/standard/fog.gl @@ -0,0 +1,202 @@ +_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(Fog,specify fog parameters) +_names(Fog,[fi]) +.EQ +delim $$ +.EN +.SH PARAMETERS +_phead(_param1) +Specifies a single-valued fog parameter. +_const(FOG_MODE), +_const(FOG_DENSITY), +_const(FOG_START), +_const(FOG_END), +and +_const(FOG_INDEX) +are accepted. +_phead(_param2) +Specifies the value that _param1 will be set to. +_names(Fog,[fi]v) +.SH PARAMETERS +_phead(_param1) +Specifies a fog parameter. +_const(FOG_MODE), +_const(FOG_DENSITY), +_const(FOG_START), +_const(FOG_END), +_const(FOG_INDEX), +and +_const(FOG_COLOR) +are accepted. +_phead(_param2) +Specifies the value or values to be assigned to _param1. +_const(FOG_COLOR) requires an array of four values. +All other parameters accept an array containing only a single value. +.SH DESCRIPTION +Fog is initially disabled. +While enabled, fog affects rasterized geometry, +bitmaps, and pixel blocks, but not buffer clear operations. To enable +and disable fog, call _cmnd(Enable) and _cmnd(Disable) with argument +_const(FOG). +.P +_cmnd assigns the value or values in _param2 to the fog parameter +specified by _param1. +The following values are accepted for _param1: +.TP 20 +_const(FOG_MODE) +_param2 is a single integer or floating-point value that specifies +the equation to be used to compute the fog blend factor, $f$. +Three symbolic constants are accepted: +_const(LINEAR), +_const(EXP), +and _const(EXP2). +The equations corresponding to these symbolic constants are defined below. +The initial fog mode is _const(EXP). +.TP +_const(FOG_DENSITY) +_param2 is a single integer or floating-point value that specifies $density$, +the fog density used in both exponential fog equations. +Only nonnegative densities are accepted. +The initial fog density is 1. +.TP +_const(FOG_START) +_param2 is a single integer or floating-point value that specifies $start$, +the near distance used in the linear fog equation. +The initial near distance is 0. +.TP +_const(FOG_END) +_param2 is a single integer or floating-point value that specifies $end$, +the far distance used in the linear fog equation. +The initial far distance is 1. +.TP +_const(FOG_INDEX) +_param2 is a single integer or floating-point value that specifies +$i sub f$, +the fog color index. +The initial fog index is 0. +.TP +_const(FOG_COLOR) +_param2 contains four integer or floating-point values that specify +$C sub f$, the fog color. +Integer values are mapped linearly such that the most positive representable +value maps to 1.0, +and the most negative representable value maps to \-1.0. +Floating-point values are mapped directly. +After conversion, +all color components are clamped to the range [0,1]. +The initial fog color is (0, 0, 0, 0). +.P +Fog blends a fog color with each rasterized pixel fragment's posttexturing +color using a blending factor $f$. +Factor $f$ is computed in one of three ways, +depending on the fog mode. +Let $z$ be the distance in eye coordinates from the origin to the fragment +being fogged. +The equation for _const(LINEAR) fog is +.ce + +.EQ +f ~=~ {end ~-~ z} over {end ~-~ start} +.EN + +.RE +.P +The equation for _const(EXP) fog is +.ce + +.EQ +f ~=~ e sup {-^(density ~cdot~ z)} +.EN + +.P +The equation for _const(EXP2) fog is +.ce + +.EQ +f ~=~ e sup {-^(density ~cdot~ z)} sup 2 +.EN + +.P +Regardless of the fog mode, +$f$ is clamped to the range [0,\ 1] after it is computed. +Then, +if the GL is in RGBA color mode, +the fragment's red, green, and blue colors, represented by $C sub r$, +are replaced by +.sp +.ce +.EQ +{C sub r} sup prime ~=~ f^C sub r ~+~ (1 - f)^C sub f +.EN + +.sp +Fog does not affect a fragment's alpha component. +.P +In color index mode, the fragment's color index $i sub r$ is replaced by +.sp +.ce +.EQ +{i sub r} sup prime ~=~ i sub r ~+~ (1 - f)^i sub f +.EN +.P +.SH ERRORS +_const(INVALID_ENUM) is generated if _param1 is not an accepted value, +or if _param1 is _const(FOG_MODE) and _param2 is not an accepted value. +.P +_const(INVALID_VALUE) is generated if _param1 is _const(FOG_DENSITY), +and _param2 is negative. +.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(IsEnabled) with argument _const(FOG) +.br +_cmnd(Get) with argument _const(FOG_COLOR) +.br +_cmnd(Get) with argument _const(FOG_INDEX) +.br +_cmnd(Get) with argument _const(FOG_DENSITY) +.br +_cmnd(Get) with argument _const(FOG_START) +.br +_cmnd(Get) with argument _const(FOG_END) +.br +_cmnd(Get) with argument _const(FOG_MODE) +.SH SEE ALSO +_cmnd(Enable) |