glGetLightfv, glGetLightiv

The glGetLightfv and glGetLightiv functions return light source parameter values.

void glGetLightfv(
  GLenum light,      
  GLenum pname,      
  GLfloat * params   
);
 
void glGetLightiv(
  GLenum light,   
  GLenum pname,   
  GLint * params  
);
 

Parameters

light

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 GL_LIGHTi where 0 ≤ i < GL_MAX_LIGHTS.

pname

A light source parameter for light. The following symbolic names are accepted:

GL_AMBIENT

The params parameter 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.

GL_DIFFUSE

The params parameter 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 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.

GL_SPECULAR

The params parameter 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.

GL_POSITION

The params parameter 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 glLight, unless the modelview matrix was identified at the time glLight was called.

GL_SPOT_DIRECTION

The params parameter 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 glLight, unless the modelview matrix was identified at the time glLight 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.

GL_SPOT_EXPONENT

The params parameter 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.

GL_SPOT_CUTOFF

The params parameter 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.

GL_CONSTANT_ATTENUATION

The params parameter 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.

GL_LINEAR_ATTENUATION

The params parameter 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.

GL_QUADRATIC_ATTENUATION

The params parameter 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.

params

Returns the requested data.

Remarks

The glGetLight function returns in params the value or values of a light source parameter. The light parameter names the light and is a symbolic name of the form GL_LIGHTi for 0 ≤ i < GL_MAX_LIGHTS, where GL_MAX_LIGHTS is an implementation-dependent constant that is greater than or equal to eight. The pname parameter specifies one of ten light source parameters, again by symbolic name.

It is always the case that GL_LIGHTi = GL_LIGHT0 + i.

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

Error Codes

The following are the error codes generated and their conditions.

QuickInfo

  Windows NT: Use version 3.5 and later.
  Windows: Use Windows 95 and later.
  Windows CE: Unsupported.
  Header: Declared in gl.h.
  Import Library: Link with opengl32.lib.

See Also

glBegin, glEnd, glLight