GL occlusion from point light - opengl

Question

My scene is quite simple that I have two spheres placed close to each other. I have one point light in the scene and set the position of it to be inside of one of the two spheres. However the other sphere can still get the light from that point light. What I want is the light is occluded by the sphere.
My context is the followings:
glShadeModel(GL_SMOOTH);
glEnable(GL_DEPTH_TEST);
glDepthFunc( GL_LEQUAL );
glEnable(GL_CULL_FACE);
glCullFace(GL_BACK);
glEnable(GL_MULTISAMPLE);
glHint(GL_LINE_SMOOTH_HINT, GL_NICEST);
glHint(GL_POINT_SMOOTH_HINT, GL_NICEST);
glHint(GL_POLYGON_SMOOTH_HINT, GL_NICEST);
glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
glEnable(GL_COLOR_MATERIAL);
glColorMaterial(GL_FRONT, GL_AMBIENT_AND_DIFFUSE);
glEnable(GL_LIGHTING);
// Light's color
GLfloat ambientColor[] = { 0.3f, 0.3f, 0.3f, 1.0f };
GLfloat diffuseColor[] = { 1.0f, 0.0f, 1.0, 1.0f };
GLfloat lightPosition[] = {0, 0, 0, 1.0f };
glLightfv(GL_LIGHT0, GL_AMBIENT, ambientColor);
glLightfv(GL_LIGHT0, GL_DIFFUSE, diffuseColor);
glLightfv(GL_LIGHT0, GL_POSITION, lightPosition);
glEnable(GL_LIGHT0);
Do I miss something?

Answer 1

When light is blocked by an interposed object between the surface and the light, that's called a shadow. The fixed-function OpenGL lighting system doesn't do shadows. OpenGL is just a triangle renderer; it doesn't know about objects, a scene, or anything. The basic assumption with any light is that there is no occluding surface between the light and the triangle.
If you want shadows, then you're going to have to manually implement one of the various shadowing techniques.