IRIX Base Documentation 2002 November/SGI IRIX Base Documentation 2002 November.iso/usr/share/catman/g_man/cat3/OpenGL/glgetlight.z/glgetlight

Text File | 2002-10-03 | 13.0 KB | 199 lines

ggggllllGGGGeeeettttLLLLiiiigggghhhhtttt((((3333GGGG))))                 OOOOppppeeeennnnGGGGLLLL RRRReeeeffffeeeerrrreeeennnncccceeee                 ggggllllGGGGeeeettttLLLLiiiigggghhhhtttt((((3333GGGG))))



NNNNAAAAMMMMEEEE
     ggggllllGGGGeeeettttLLLLiiiigggghhhhttttffffvvvv,,,, ggggllllGGGGeeeettttLLLLiiiigggghhhhttttiiiivvvv - return light source parameter values


CCCC SSSSPPPPEEEECCCCIIIIFFFFIIIICCCCAAAATTTTIIIIOOOONNNN
     void ggggllllGGGGeeeettttLLLLiiiigggghhhhttttffffvvvv( GLenum _l_i_g_h_t,
                        GLenum _p_n_a_m_e,
                        GLfloat *_p_a_r_a_m_s )
     void ggggllllGGGGeeeettttLLLLiiiigggghhhhttttiiiivvvv( GLenum _l_i_g_h_t,
                        GLenum _p_n_a_m_e,
                        GLint *_p_a_r_a_m_s )


PPPPAAAARRRRAAAAMMMMEEEETTTTEEEERRRRSSSS
     _l_i_g_h_t   Specifies a light source.  The number of possible lights depends
             on the implementation, but at least eight lights are supported.
             They are identified by symbolic names of the form GGGGLLLL____LLLLIIIIGGGGHHHHTTTTi where
             0 _< i < GGGGLLLL____MMMMAAAAXXXX____LLLLIIIIGGGGHHHHTTTTSSSS.

     _p_n_a_m_e   Specifies a light source parameter for _l_i_g_h_t.  Accepted symbolic
             names are GGGGLLLL____AAAAMMMMBBBBIIIIEEEENNNNTTTT, GGGGLLLL____DDDDIIIIFFFFFFFFUUUUSSSSEEEE, GGGGLLLL____SSSSPPPPEEEECCCCUUUULLLLAAAARRRR, GGGGLLLL____PPPPOOOOSSSSIIIITTTTIIIIOOOONNNN,
             GGGGLLLL____SSSSPPPPOOOOTTTT____DDDDIIIIRRRREEEECCCCTTTTIIIIOOOONNNN, GGGGLLLL____SSSSPPPPOOOOTTTT____EEEEXXXXPPPPOOOONNNNEEEENNNNTTTT, GGGGLLLL____SSSSPPPPOOOOTTTT____CCCCUUUUTTTTOOOOFFFFFFFF,
             GGGGLLLL____CCCCOOOONNNNSSSSTTTTAAAANNNNTTTT____AAAATTTTTTTTEEEENNNNUUUUAAAATTTTIIIIOOOONNNN, GGGGLLLL____LLLLIIIINNNNEEEEAAAARRRR____AAAATTTTTTTTEEEENNNNUUUUAAAATTTTIIIIOOOONNNN, and
             GGGGLLLL____QQQQUUUUAAAADDDDRRRRAAAATTTTIIIICCCC____AAAATTTTTTTTEEEENNNNUUUUAAAATTTTIIIIOOOONNNN.

     _p_a_r_a_m_s  Returns the requested data.

DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN
     ggggllllGGGGeeeettttLLLLiiiigggghhhhtttt returns in _p_a_r_a_m_s the value or values of a light source
     parameter.  _l_i_g_h_t names the light and is a symbolic name of the form
     GGGGLLLL____LLLLIIIIGGGGHHHHTTTTi for 0 _< i < GGGGLLLL____MMMMAAAAXXXX____LLLLIIIIGGGGHHHHTTTTSSSS, where GGGGLLLL____MMMMAAAAXXXX____LLLLIIIIGGGGHHHHTTTTSSSS is an
     implementation dependent constant that is greater than or equal to eight.
     _p_n_a_m_e specifies one of ten light source parameters, again by symbolic
     name.

     The following parameters are defined:

     GGGGLLLL____AAAAMMMMBBBBIIIIEEEENNNNTTTT          _p_a_r_a_m_s returns four integer or floating-point values
                         representing the ambient intensity of the light
                         source.  Integer values, when requested, are linearly
                         mapped from the internal floating-point
                         representation such that 1.0 maps to the most
                         positive representable integer value, and -1.0 maps
                         to the most negative representable integer value.  If
                         the internal value is outside the range [-1, 1], the
                         corresponding integer return value is undefined. The
                         initial value is (0, 0, 0, 1).

     GGGGLLLL____DDDDIIIIFFFFFFFFUUUUSSSSEEEE          _p_a_r_a_m_s returns four integer or floating-point values
                         representing the diffuse intensity of the light
                         source.  Integer values, when requested, are linearly
                         mapped from the internal floating-point



                                                                        PPPPaaaaggggeeee 1111






ggggllllGGGGeeeettttLLLLiiiigggghhhhtttt((((3333GGGG))))                 OOOOppppeeeennnnGGGGLLLL RRRReeeeffffeeeerrrreeeennnncccceeee                 ggggllllGGGGeeeettttLLLLiiiigggghhhhtttt((((3333GGGG))))



                         representation such that 1.0 maps to the most
                         positive representable integer value, and -1.0 maps
                         to the most negative representable integer value.  If
                         the internal value is outside the range [-1, 1], the
                         corresponding integer return value is undefined. The
                         initial value for GGGGLLLL____LLLLIIIIGGGGHHHHTTTT0000 is (1, 1, 1, 1); for
                         other lights, the initial value is (0, 0, 0, 0).

     GGGGLLLL____SSSSPPPPEEEECCCCUUUULLLLAAAARRRR         _p_a_r_a_m_s returns four integer or floating-point values
                         representing the specular intensity of the light
                         source.  Integer values, when requested, are linearly
                         mapped from the internal floating-point
                         representation such that 1.0 maps to the most
                         positive representable integer value, and -1.0 maps
                         to the most negative representable integer value.  If
                         the internal value is outside the range [-1, 1], the
                         corresponding integer return value is undefined. The
                         initial value for GGGGLLLL____LLLLIIIIGGGGHHHHTTTT0000 is (1, 1, 1, 1); for
                         other lights, the initial value is (0, 0, 0, 0).

     GGGGLLLL____PPPPOOOOSSSSIIIITTTTIIIIOOOONNNN         _p_a_r_a_m_s returns four integer or floating-point values
                         representing the position of the light source.
                         Integer values, when requested, are computed by
                         rounding the internal floating-point values to the
                         nearest integer value.  The returned values are those
                         maintained in eye coordinates.  They will not be
                         equal to the values specified using ggggllllLLLLiiiigggghhhhtttt, unless
                         the modelview matrix was identity at the time ggggllllLLLLiiiigggghhhhtttt
                         was called. The initial value is (0, 0, 1, 0).

     GGGGLLLL____SSSSPPPPOOOOTTTT____DDDDIIIIRRRREEEECCCCTTTTIIIIOOOONNNN   _p_a_r_a_m_s returns three integer or floating-point values
                         representing the direction of the light source.
                         Integer values, when requested, are computed by
                         rounding the internal floating-point values to the
                         nearest integer value.  The returned values are those
                         maintained in eye coordinates.  They will not be
                         equal to the values specified using ggggllllLLLLiiiigggghhhhtttt, unless
                         the modelview matrix was identity at the time ggggllllLLLLiiiigggghhhhtttt
                         was called.  Although spot direction is normalized
                         before being used in the lighting equation, the
                         returned values are the transformed versions of the
                         specified values prior to normalization. The initial
                         value is (0, 0, -1).

     GGGGLLLL____SSSSPPPPOOOOTTTT____EEEEXXXXPPPPOOOONNNNEEEENNNNTTTT    _p_a_r_a_m_s returns a single integer or floating-point
                         value representing the spot exponent of the light.
                         An integer value, when requested, is computed by
                         rounding the internal floating-point representation
                         to the nearest integer. The initial value is 0.






                                                                        PPPPaaaaggggeeee 2222






ggggllllGGGGeeeettttLLLLiiiigggghhhhtttt((((3333GGGG))))                 OOOOppppeeeennnnGGGGLLLL RRRReeeeffffeeeerrrreeeennnncccceeee                 ggggllllGGGGeeeettttLLLLiiiigggghhhhtttt((((3333GGGG))))



     GGGGLLLL____SSSSPPPPOOOOTTTT____CCCCUUUUTTTTOOOOFFFFFFFF      _p_a_r_a_m_s returns a single integer or floating-point
                         value representing the spot cutoff angle of the
                         light.  An integer value, when requested, is computed
                         by rounding the internal floating-point
                         representation to the nearest integer. The initial
                         value is 180.

     GGGGLLLL____CCCCOOOONNNNSSSSTTTTAAAANNNNTTTT____AAAATTTTTTTTEEEENNNNUUUUAAAATTTTIIIIOOOONNNN
                         _p_a_r_a_m_s returns a single integer or floating-point
                         value representing the constant (not distance-
                         related) attenuation of the light.  An integer value,
                         when requested, is computed by rounding the internal
                         floating-point representation to the nearest integer.
                         The initial value is 1.

     GGGGLLLL____LLLLIIIINNNNEEEEAAAARRRR____AAAATTTTTTTTEEEENNNNUUUUAAAATTTTIIIIOOOONNNN
                         _p_a_r_a_m_s returns a single integer or floating-point
                         value representing the linear attenuation of the
                         light.  An integer value, when requested, is computed
                         by rounding the internal floating-point
                         representation to the nearest integer. The initial
                         value is 0.

     GGGGLLLL____QQQQUUUUAAAADDDDRRRRAAAATTTTIIIICCCC____AAAATTTTTTTTEEEENNNNUUUUAAAATTTTIIIIOOOONNNN
                         _p_a_r_a_m_s returns a single integer or floating-point
                         value representing the quadratic attenuation of the
                         light.  An integer value, when requested, is computed
                         by rounding the internal floating-point
                         representation to the nearest integer. The initial
                         value is 0.

NNNNOOOOTTTTEEEESSSS
     It is always the case that GGGGLLLL____LLLLIIIIGGGGHHHHTTTTi = GGGGLLLL____LLLLIIIIGGGGHHHHTTTT0000 + i.

     If an error is generated, no change is made to the contents of _p_a_r_a_m_s.

EEEERRRRRRRROOOORRRRSSSS
     GGGGLLLL____IIIINNNNVVVVAAAALLLLIIIIDDDD____EEEENNNNUUUUMMMM is generated if _l_i_g_h_t or _p_n_a_m_e is not an accepted value.

     GGGGLLLL____IIIINNNNVVVVAAAALLLLIIIIDDDD____OOOOPPPPEEEERRRRAAAATTTTIIIIOOOONNNN is generated if ggggllllGGGGeeeettttLLLLiiiigggghhhhtttt is executed between the
     execution of ggggllllBBBBeeeeggggiiiinnnn and the corresponding execution of ggggllllEEEEnnnndddd.


SSSSEEEEEEEE AAAALLLLSSSSOOOO
     ggggllllLLLLiiiigggghhhhtttt










                                                                        PPPPaaaaggggeeee 3333