I'm trying to enable lighting in lwjgl according to the method described by NeHe and this post. However, no matter what I try, all faces of my shapes always receive the same amount of light, or, in the case of a spinning shape, the amount of lighting seems to oscillate. All faces are lit up by the same amount, which changes as the pyramid rotates. Concrete example (apologies for the length):

Note how all panels are always the same brightness, but the brightness varies with the pyramid's rotation.

This is using lwjgl 2.8.3 on Mac OS X.

package com;

import com.zarkonnen.lwjgltest.Main;
import org.lwjgl.opengl.Display;
import org.lwjgl.opengl.DisplayMode;
import org.lwjgl.opengl.GL11;
import org.newdawn.slick.opengl.Texture;
import org.newdawn.slick.opengl.TextureLoader;
import org.lwjgl.util.glu.*;
import org.lwjgl.input.Keyboard;

import java.nio.FloatBuffer;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;

/**
 *
 * @author penguin
 */
public class main {

    public static void main(String[] args) {
        try {
            Display.setDisplayMode(new DisplayMode(800, 600));
            Display.setTitle("3D Pyramid");
            Display.create();
        } catch (Exception e) {
        }
        initGL();

        float rtri = 0.0f;
        Texture texture = null;
        try {
            texture = TextureLoader.getTexture("png", Main.class.getResourceAsStream("tex.png"));
        } catch (Exception ex) {
            ex.printStackTrace();
        }
        while (!Display.isCloseRequested()) {
            // Draw a Triangle :D

            GL11.glClear(GL11.GL_COLOR_BUFFER_BIT | GL11.GL_DEPTH_BUFFER_BIT);

            GL11.glLoadIdentity();

            GL11.glTranslatef(0.0f, 0.0f, -10.0f);

            GL11.glRotatef(rtri, 0.0f, 1.0f, 0.0f);

            texture.bind();

            GL11.glBegin(GL11.GL_TRIANGLES);

            GL11.glTexCoord2f(0.0f, 1.0f);
            GL11.glVertex3f(0.0f, 1.0f, 0.0f);
            GL11.glTexCoord2f(-1.0f, -1.0f);
            GL11.glVertex3f(-1.0f, -1.0f, 1.0f);
            GL11.glTexCoord2f(1.0f, -1.0f);
            GL11.glVertex3f(1.0f, -1.0f, 1.0f);

            GL11.glTexCoord2f(0.0f, 1.0f);
            GL11.glVertex3f(0.0f, 1.0f, 0.0f);
            GL11.glTexCoord2f(-1.0f, -1.0f);
            GL11.glVertex3f(1.0f, -1.0f, 1.0f);
            GL11.glTexCoord2f(1.0f, -1.0f);
            GL11.glVertex3f(1.0f, -1.0f, -1.0f);

            GL11.glTexCoord2f(0.0f, 1.0f);
            GL11.glVertex3f(0.0f, 1.0f, 0.0f);
            GL11.glTexCoord2f(-1.0f, -1.0f);
            GL11.glVertex3f(-1.0f, -1.0f, -1.0f);
            GL11.glTexCoord2f(1.0f, -1.0f);
            GL11.glVertex3f(1.0f, -1.0f, -1.0f);

            GL11.glTexCoord2f(0.0f, 1.0f);
            GL11.glVertex3f(0.0f, 1.0f, 0.0f);
            GL11.glTexCoord2f(-1.0f, -1.0f);
            GL11.glVertex3f(-1.0f, -1.0f, -1.0f);
            GL11.glTexCoord2f(1.0f, -1.0f);
            GL11.glVertex3f(-1.0f, -1.0f, 1.0f);


            GL11.glEnd();

            GL11.glBegin(GL11.GL_QUADS);
            GL11.glVertex3f(1.0f, -1.0f, 1.0f);
            GL11.glVertex3f(1.0f, -1.0f, -1.0f);
            GL11.glVertex3f(-1.0f, -1.0f, -1.0f);
            GL11.glVertex3f(-1.0f, -1.0f, 1.0f);
            GL11.glEnd();

            Display.update();
            rtri += 0.05f;
            // Exit-Key = ESC
            boolean exitPressed = Keyboard.isKeyDown(Keyboard.KEY_ESCAPE);
            if (exitPressed) {
                System.out.println("Escape was pressed!");
                Display.destroy();

            }
        }

        Display.destroy();
    }

    private static void initGL() {
        GL11.glEnable(GL11.GL_LIGHTING);
        GL11.glMatrixMode(GL11.GL_PROJECTION);
        GL11.glLoadIdentity();
        GLU.gluPerspective(45.0f, ((float) 800) / ((float) 600), 0.1f, 100.0f);
        GL11.glMatrixMode(GL11.GL_MODELVIEW);
        GL11.glLoadIdentity();

        GL11.glEnable(GL11.GL_TEXTURE_2D);
        GL11.glShadeModel(GL11.GL_SMOOTH);
        GL11.glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
        GL11.glClearDepth(1.0f);
        GL11.glEnable(GL11.GL_DEPTH_TEST);
        GL11.glDepthFunc(GL11.GL_LEQUAL);
        GL11.glHint(GL11.GL_PERSPECTIVE_CORRECTION_HINT, GL11.GL_NICEST);
        float lightAmbient[] = {0.5f, 0.5f, 0.5f, 1.0f};  // Ambient Light Values
        float lightDiffuse[] = {1.0f, 1.0f, 1.0f, 1.0f};      // Diffuse Light Values
        float lightPosition[] = {0.0f, 0.0f, 2.0f, 1.0f}; // Light Position

        ByteBuffer temp = ByteBuffer.allocateDirect(16);
        temp.order(ByteOrder.nativeOrder());
        GL11.glLight(GL11.GL_LIGHT1, GL11.GL_AMBIENT, (FloatBuffer) temp.asFloatBuffer().put(lightAmbient).flip());              // Setup The Ambient Light
        GL11.glLight(GL11.GL_LIGHT1, GL11.GL_DIFFUSE, (FloatBuffer) temp.asFloatBuffer().put(lightDiffuse).flip());              // Setup The Diffuse Light
        GL11.glLight(GL11.GL_LIGHT1, GL11.GL_POSITION, (FloatBuffer) temp.asFloatBuffer().put(lightPosition).flip());         // Position The Light
        GL11.glEnable(GL11.GL_LIGHT1);                          // Enable Light One
    }
}