Open GL Lighting Problem

Question

I've been working on a game engine for a month now, and I've finished the basic OpenGL stuff. However, the one thing that I can't get to work like I expect it to is the lighting. (Note: This is the first time I seriously worked with OpenGL)

What I want is a close to realistic lighting simulation - where the surfaces facing the light are lit up more than those farther, etc.. The basic light should have a position and a color. This is how I thought it could be implemented:

float lightv[4]; // populated with (0.6, 0.6, 0.6, 1)
float positionv[4]; // populated with (0, 10, 0, 1)
int lightID = GL_LIGHT0;
int attenuationType = GL_LINEAR_ATTENUATION;
float attenuationValue = 1;
glLightf(lightID, attenuationType, attenuationValue);
glLightfv(lightID, GL_DIFFUSE, lightv);
glLightfv(lightID, GL_POSITION, positionv);
glEnable(lightID);

Instead of doing what I expect it to do, it gives me lighting as if there was a light where the camera is! Every surface has the same lighting!

What am I doing wrong?

Thank you, I appreciate it.

Answer 1

Set your light position after you set up your GL_MODELVIEW transform, since it's affected by the current transform matrix. Otherwise you get the "headlamp" effect you have discovered.

Answer 2

The first thing to do is make sure you have glEnable(GL_LIGHTING); called at some point. Past that, the first thing to check is that your normals are correct. For lighting to work properly you will need to have a normal set for every vertex you draw. If you have already set your normals, you should make sure that they are all of unit length. If they do not have a length of one, lighting can act oddly. If that is all as it should be, you should keep in mind that when you set the position of a light, it is modified by the current Modelview matrix as if it were a vertex. If none of those things are relevant, I'll see if I can think of something further.