glGetFragmentLight(3G)
glGetFragmentLightfvSGIX, glGetFragmentLightivSGIX - return fragment light source parameter values
As shipped in IRIX 6.5.30. Added in IRIX 6.5.15.
NAME glGetFragmentLightfvSGIX, glGetFragmentLightivSGIX - return fragment light source parameter values C SPECIFICATION void glGetFragmentLightfvSGIX( GLenum light, GLenum pname, GLfloat *params ) void glGetFragmentLightivSGIX( GLenum light, GLenum pname, GLint *params ) PARAMETERS light Specifies a fragment light source. The number of possible fragment lights depends on the implementation. They are identified by symbolic names of the form GL_FRAGMENT_LIGHTi_SGIX where 0 < i < GL_MAX_FRAGMENT_LIGHTS_SGIX. pname Specifies a fragment light source parameter for light. Accepted symbolic names are GL_AMBIENT, GL_DIFFUSE, GL_SPECULAR, GL_POSITION, GL_SPOT_DIRECTION, GL_SPOT_EXPONENT, GL_SPOT_CUTOFF, GL_CONSTANT_ATTENUATION, GL_LINEAR_ATTENUATION, and GL_QUADRATIC_ATTENUATION. params Returns the requested data. DESCRIPTION glGetFragmentLight returns in params the value or values of a fragment light source parameter. light names the fragment light and is a symbolic name of the form GL_FRAGMENT_LIGHTi_SGIX for 0 < i < GL_MAX_FRAGMENT_LIGHTS_SGIX, where GL_MAX_FRAGMENT_LIGHTS_SGIX is an implementation dependent constant. pname specifies one of ten fragment light source parameters, again by symbolic name. The following parameters are defined: GL_AMBIENT params returns four integer or floating-point values representing the ambient intensity of the fragment 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). GL_DIFFUSE params returns four integer or floating-point values representing the diffuse intensity of the fragment 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 GL_FRAGMENT_LIGHT0_SGIX is (1, 1, 1, 1); for other fragment lights, the initial value is (0, 0, 0, 0). GL_SPECULAR params returns four integer or floating-point values representing the specular intensity of the fragment 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 GL_FRAGMENT_LIGHT0_SGIX is (1, 1, 1, 1); for other fragment lights, the initial value is (0, 0, 0, 0). GL_POSITION params returns four integer or floating-point values representing the position of the fragment 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 glFragmentLight, unless the modelview matrix was identity at the time glFragmentLight was called. The initial value is (0, 0, 1, 0). GL_SPOT_DIRECTION params returns three integer or floating-point values representing the direction of the fragment 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 glFragmentLight, unless the modelview matrix was identity at the time glFragmentLight was called. Although spot direction is normalized before being used in the fragment lighting equation, the returned values are the transformed versions of the specified values prior to normalization. The initial value is (0, 0, -1). GL_SPOT_EXPONENT params returns a single integer or floating-point value representing the spot exponent of the fragment light. An integer value, when requested, is computed by rounding the internal floating-point representation to the nearest integer. The initial value is 0. GL_SPOT_CUTOFF params returns a single integer or floating-point value representing the spot cutoff angle of the fragment light. An integer value, when requested, is computed by rounding the internal floating-point representation to the nearest integer. The initial value is 180. GL_CONSTANT_ATTENUATION params returns a single integer or floating-point value representing the constant (not distance- related) attenuation of the fragment light. An integer value, when requested, is computed by rounding the internal floating-point representation to the nearest integer. The initial value is 1. GL_LINEAR_ATTENUATION params returns a single integer or floating-point value representing the linear attenuation of the fragment light. An integer value, when requested, is computed by rounding the internal floating-point representation to the nearest integer. The initial value is 0. GL_QUADRATIC_ATTENUATION params returns a single integer or floating-point value representing the quadratic attenuation of the fragment light. An integer value, when requested, is computed by rounding the internal floating-point representation to the nearest integer. The initial value is 0. NOTES It is always the case that GL_FRAGMENT_LIGHTi_SGIX = GL_FRAGMENT_LIGHT0_SGIX + i. If an error is generated, no change is made to the contents of params. ERRORS GL_INVALID_ENUM is generated if light or pname is not an accepted value. GL_INVALID_OPERATION is generated if glGetFragmentLight is executed between the execution of glBegin and the corresponding execution of glEnd. MACHINE DEPENDENCIES The SGIX_fragment_lighting extension is supported only on Octane2 VPro systems. SEE ALSO glFragmentLight