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diff --git a/nx-X11/extras/ogl-sample/main/doc/man/mangl/standard/light.gl b/nx-X11/extras/ogl-sample/main/doc/man/mangl/standard/light.gl new file mode 100644 index 000000000..3b6da035d --- /dev/null +++ b/nx-X11/extras/ogl-sample/main/doc/man/mangl/standard/light.gl @@ -0,0 +1,240 @@ +_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,tbl|eqn)_C_ +_C_ eqn is automatically replaced with neqn for nroff +_header(Light,set light source parameters) +_names(Light,[fi]) +.EQ +delim $$ +.EN +.SH PARAMETERS +_phead(_param1) +Specifies a light. +The number of lights depends on the implementation, +but at least eight lights are supported. +They are identified by symbolic names of the form _const(LIGHT)$i$ +where 0 \(<= $ i $ < _const(MAX_LIGHTS). +_phead(_param2) +Specifies a single-valued light source parameter for _param1. +_const(SPOT_EXPONENT), +_const(SPOT_CUTOFF), +_const(CONSTANT_ATTENUATION), +_const(LINEAR_ATTENUATION), and +_const(QUADRATIC_ATTENUATION) are accepted. +_phead(_param3) +Specifies the value that parameter _param2 of light source _param1 +will be set to. +_names(Light,[fi]v) +.SH PARAMETERS +_phead(_param1) +Specifies a light. +The number of lights depends on the implementation, but +at least eight lights are supported. +They are identified by symbolic names of the form _const(LIGHT)$i$ +where 0 \(<= $ i $ < _const(MAX_LIGHTS). +_phead(_param2) +Specifies a light source parameter for _param1. +_const(AMBIENT), +_const(DIFFUSE), +_const(SPECULAR), +_const(POSITION), +_const(SPOT_CUTOFF), +_const(SPOT_DIRECTION), +_const(SPOT_EXPONENT), +_const(CONSTANT_ATTENUATION), +_const(LINEAR_ATTENUATION), and +_const(QUADRATIC_ATTENUATION) are accepted. +_phead(_param3) +Specifies a pointer to the value or values that parameter _param2 +of light source _param1 will be set to. +.SH DESCRIPTION +_cmnd sets the values of individual light source parameters. +_param1 names the light and is a symbolic name of the form _const(LIGHT)$i$, +where 0 \(<= i < _const(MAX_LIGHTS). +_param2 specifies one of ten light source parameters, +again by symbolic name. +_param3 is either a single value or a pointer to an array that contains +the new values. +.P +To enable and disable lighting calculation, call _cmnd(Enable) +and _cmnd(Disable) with argument _const(LIGHTING). Lighting is +initially disabled. +When it is enabled, +light sources that are enabled contribute to the lighting calculation. +Light source $i$ is enabled and disabled using _cmnd(Enable) and +_cmnd(Disable) with argument _const(LIGHT)$i$. +.P +The ten light parameters are as follows: +.TP 20 +_const(AMBIENT) +_param3 contains four integer or floating-point values that specify +the ambient RGBA intensity of the light. +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. +Neither integer nor floating-point values are clamped. +The initial ambient light intensity is (0, 0, 0, 1). +.TP +_const(DIFFUSE) +_param3 contains four integer or floating-point values that specify +the diffuse RGBA intensity of the light. +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. +Neither integer nor floating-point values are clamped. +The initial value +for _const(LIGHT0) is (1, 1, 1, 1); for other lights, the +initial value is (0, 0, 0, 0). +.TP +_const(SPECULAR) +_param3 contains four integer or floating-point values that specify +the specular RGBA intensity of the light. +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. +Neither integer nor floating-point values are clamped. +The initial value +for _const(LIGHT0) is (1, 1, 1, 1); for other lights, the +initial value is (0, 0, 0, 0). +.TP +_const(POSITION) +_param3 contains four integer or floating-point values that specify +the position of the light in homogeneous object coordinates. +Both integer and floating-point values are mapped directly. +Neither integer nor floating-point values are clamped. +.IP +The position is transformed by the modelview matrix when +_cmnd is called (just as if it were a point), +and it is stored in eye coordinates. +If the $w$ component of the position is 0, +the light is treated as a directional source. +Diffuse and specular lighting calculations take the light's direction, +but not its actual position, +into account, +and attenuation is disabled. +Otherwise, +diffuse and specular lighting calculations are based on the actual location +of the light in eye coordinates, +and attenuation is enabled. +The initial position is (0, 0, 1, 0); +thus, the initial light source is directional, +parallel to, and in the direction of the $-z$ axis. +.TP +_const(SPOT_DIRECTION) +_param3 contains three integer or floating-point values that specify +the direction of the light in homogeneous object coordinates. +Both integer and floating-point values are mapped directly. +Neither integer nor floating-point values are clamped. +.IP +The spot direction is transformed by the inverse of the modelview matrix when +_cmnd is called (just as if it were a normal), +and it is stored in eye coordinates. +It is significant only when _const(SPOT_CUTOFF) is not 180, +which it is initially. +The initial direction is (0, 0, \-1). +.TP +_const(SPOT_EXPONENT) +_param3 is a single integer or floating-point value that specifies +the intensity distribution of the light. +Integer and floating-point values are mapped directly. +Only values in the range [0,128] are accepted. +.IP +Effective light intensity is attenuated by the cosine of the angle between +the direction of the light and the direction from the light to the vertex +being lighted, +raised to the power of the spot exponent. +Thus, higher spot exponents result in a more focused light source, +regardless of the spot cutoff angle (see _const(SPOT_CUTOFF), next paragraph). +The initial spot exponent is 0, +resulting in uniform light distribution. +.TP +_const(SPOT_CUTOFF) +_param3 is a single integer or floating-point value that specifies +the maximum spread angle of a light source. +Integer and floating-point values are mapped directly. +Only values in the range [0,90] and the special value 180 +are accepted. +If the angle between the direction of the light and the direction from the +light to the vertex being lighted is greater than the spot cutoff angle, +the light is completely masked. +.BP +Otherwise, its intensity is controlled by the spot exponent and the +attenuation factors. +The initial spot cutoff is 180, +resulting in uniform light distribution. +.TP +_const(CONSTANT_ATTENUATION) +.TP +_const(LINEAR_ATTENUATION ) +.TP +_const(QUADRATIC_ATTENUATION) +_param3 is a single integer or floating-point value that specifies +one of the three light attenuation factors. +Integer and floating-point values are mapped directly. +Only nonnegative values are accepted. +If the light is positional, +rather than directional, +its intensity is attenuated by the reciprocal of the sum of the constant +factor, the linear factor times the distance between the light +and the vertex being lighted, +and the quadratic factor times the square of the same distance. +The initial attenuation factors are (1, 0, 0), +resulting in no attenuation. +.SH NOTES +It is always the case that _const(LIGHT)$i$ = _const(LIGHT0) + $i$. +.SH ERRORS +_const(INVALID_ENUM) is generated if either _param1 or _param2 +is not an accepted value. +.P +_const(INVALID_VALUE) is generated if a spot exponent value is specified +outside the range [0,128], +or if spot cutoff is specified outside the range [0,90] (except for the +special value 180), +or if a negative attenuation factor is specified. +.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(GetLight) +.br +_cmnd(IsEnabled) with argument _const(LIGHTING) +.SH SEE ALSO +_cmnd(ColorMaterial), +_cmnd(LightModel), +_cmnd(Material) |