Lighting -- Ambient Intensity

Ambient Intensity

Light sources do not contribute to the ambient lighting in a scene unless you so specify.

GLvoid glLightfv( GLenum light, GL_AMBIENT, 
                  const GLfloat *params )

A light's contribution to the scene's ambient light
Light coming from a source after it has been scattered by the environment
Goes away when the light is turned off
params is an array containing an RGBA color value

Notes:

The GL_AMBIENT parameter refers to the RGBA intensity of the ambient light that a particular light source adds to the scene.

By default, light sources do not contribute to the ambient lighting in a scene. That is, the default ambient intensity is (0.0, 0.0, 0.0, 1.0) for all lights.