glLight man page on RedHat

Man page or keyword search:  
man Server   29550 pages
apropos Keyword Search (all sections)
Output format
RedHat logo
[printable version]

GLLIGHT(3G)			 OpenGL Manual			   GLLIGHT(3G)

NAME
       glLight - set light source parameters

C SPECIFICATION
       void glLightf(GLenum light, GLenum pname, GLfloat param);

       void glLighti(GLenum light, GLenum pname, GLint param);

PARAMETERS
       light
	   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 GL_LIGHT i, where i ranges
	   from 0 to the value of GL_MAX_LIGHTS - 1.

       pname
	   Specifies a single-valued light source parameter for light.
	   GL_SPOT_EXPONENT, GL_SPOT_CUTOFF, GL_CONSTANT_ATTENUATION,
	   GL_LINEAR_ATTENUATION, and GL_QUADRATIC_ATTENUATION are accepted.

       param
	   Specifies the value that parameter pname of light source light will
	   be set to.

C SPECIFICATION
       void glLightfv(GLenum light, GLenum pname, const GLfloat * params);

       void glLightiv(GLenum light, GLenum pname, const GLint * params);

PARAMETERS
       light
	   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 GL_LIGHT i, where i ranges
	   from 0 to the value of GL_MAX_LIGHTS - 1.

       pname
	   Specifies a light source parameter for light.  GL_AMBIENT,
	   GL_DIFFUSE, GL_SPECULAR, GL_POSITION, GL_SPOT_CUTOFF,
	   GL_SPOT_DIRECTION, GL_SPOT_EXPONENT, GL_CONSTANT_ATTENUATION,
	   GL_LINEAR_ATTENUATION, and GL_QUADRATIC_ATTENUATION are accepted.

       params
	   Specifies a pointer to the value or values that parameter pname of
	   light source light will be set to.

DESCRIPTION
       glLight sets the values of individual light source parameters.  light
       names the light and is a symbolic name of the form GL_LIGHT i, where i
       ranges from 0 to the value of GL_MAX_LIGHTS - 1.	 pname specifies one
       of ten light source parameters, again by symbolic name.	params is
       either a single value or a pointer to an array that contains the new
       values.

       To enable and disable lighting calculation, call glEnable() and
       glDisable() with argument GL_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
       glEnable() and glDisable() with argument GL_LIGHT i.

       The ten light parameters are as follows:

       GL_AMBIENT

	   params 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).

       GL_DIFFUSE

	   params 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 GL_LIGHT0
	   is (1, 1, 1, 1); for other lights, the initial value is (0, 0, 0,
	   1).

       GL_SPECULAR

	   params 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 GL_LIGHT0
	   is (1, 1, 1, 1); for other lights, the initial value is (0, 0, 0,
	   1).

       GL_POSITION

	   params 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.

	   The position is transformed by the modelview matrix when glLight 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.

       GL_SPOT_DIRECTION

	   params 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.

	   The spot direction is transformed by the upper 3x3 of the modelview
	   matrix when glLight is called, and it is stored in eye coordinates.
	   It is significant only when GL_SPOT_CUTOFF is not 180, which it is
	   initially. The initial direction is 0 0 -1.

       GL_SPOT_EXPONENT

	   params 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.

	   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
	   GL_SPOT_CUTOFF, next paragraph). The initial spot exponent is 0,
	   resulting in uniform light distribution.

       GL_SPOT_CUTOFF

	   params 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. Otherwise, its intensity is controlled
	   by the spot exponent and the attenuation factors. The initial spot
	   cutoff is 180, resulting in uniform light distribution.

       GL_CONSTANT_ATTENUATION

       GL_LINEAR_ATTENUATION

       GL_QUADRATIC_ATTENUATION

	   params 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.

NOTES
       It is always the case that GL_LIGHT i = GL_LIGHT0 + i.

ERRORS
       GL_INVALID_ENUM is generated if either light or pname is not an
       accepted value.

       GL_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.

       GL_INVALID_OPERATION is generated if glLight is executed between the
       execution of glBegin() and the corresponding execution of glEnd().

ASSOCIATED GETS
       glGetLight()

       glIsEnabled() with argument GL_LIGHTING

SEE ALSO
       glColorMaterial(), glLightModel(), glMaterial()

COPYRIGHT
       Copyright © 1991-2006 Silicon Graphics, Inc. This document is licensed
       under the SGI Free Software B License. For details, see
       http://oss.sgi.com/projects/FreeB/.

AUTHORS
       opengl.org

opengl.org			  03/16/2013			   GLLIGHT(3G)
[top]

List of man pages available for RedHat

Copyright (c) for man pages and the logo by the respective OS vendor.

For those who want to learn more, the polarhome community provides shell access and support.

[legal] [privacy] [GNU] [policy] [cookies] [netiquette] [sponsors] [FAQ]
Tweet
Polarhome, production since 1999.
Member of Polarhome portal.
Based on Fawad Halim's script.
....................................................................
Vote for polarhome
Free Shell Accounts :: the biggest list on the net