This example shows how to use 3 different fog filters: how to change the color of the fog, how to set how far into the screen the fog starts and how far into the screen it ends.

This is the Java port of the one of the NeHe OpenGL tutorials.

You can get complete IntelliJ IDEA project structure (all source, resources, build script, …) by downloading the source distribution from here.

The original post of the programmer who ported the examples can be found here.

 package demos.nehe.lesson16;

import demos.common.GLDisplay;

/**
 * @author Jeff Kirby
 */
public class Lesson16 {
    public static void main(String[] args) {
        GLDisplay neheGLDisplay = GLDisplay.createGLDisplay("Lesson 16: Cool looking fog");
        Renderer renderer = new Renderer();
        InputHandler inputHandler = new InputHandler(renderer, neheGLDisplay);
        neheGLDisplay.addGLEventListener(renderer);
        neheGLDisplay.addKeyListener(inputHandler);
        neheGLDisplay.start();
    }
}


package demos.nehe.lesson16;

import demos.common.GLDisplay;

import javax.swing.*;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;

class InputHandler extends KeyAdapter {
    private Renderer renderer;

    public InputHandler(Renderer renderer, GLDisplay display) {
        this.renderer = renderer;
        display.registerKeyStrokeForHelp(
                KeyStroke.getKeyStroke(KeyEvent.VK_F, 0), "Switch texture filter");
        
        display.registerKeyStrokeForHelp(
                KeyStroke.getKeyStroke(KeyEvent.VK_G, 0), "Switch fog mode");
        
        display.registerKeyStrokeForHelp(
                KeyStroke.getKeyStroke(KeyEvent.VK_L, 0), "Toggle lighting");
        
        display.registerKeyStrokeForHelp(
                KeyStroke.getKeyStroke(KeyEvent.VK_UP, 0), "Increase X rotation speed");
        
        display.registerKeyStrokeForHelp(
                KeyStroke.getKeyStroke(KeyEvent.VK_DOWN, 0), "Decrease X rotation speed");
        
        display.registerKeyStrokeForHelp(
                KeyStroke.getKeyStroke(KeyEvent.VK_LEFT, 0), "Decrease Y rotation speed");
        
        display.registerKeyStrokeForHelp(
                KeyStroke.getKeyStroke(KeyEvent.VK_RIGHT, 0), "Increase Y rotation speed");
        
        display.registerKeyStrokeForHelp(
                KeyStroke.getKeyStroke(KeyEvent.VK_PAGE_UP, 0), "Zoom in");
        
        display.registerKeyStrokeForHelp(
                KeyStroke.getKeyStroke(KeyEvent.VK_PAGE_DOWN, 0), "Zoom out");
    }

    public void keyPressed(KeyEvent e) {
        processKeyEvent(e, true);
    }

    public void keyReleased(KeyEvent e) {
        switch (e.getKeyCode()) {
            case KeyEvent.VK_F:
                renderer.switchFilter();
                break;
            case KeyEvent.VK_G:
                renderer.switchFogMode();
                break;
            case KeyEvent.VK_L:
                renderer.toggleLighting();
                break;
            default:
                processKeyEvent(e, false);
        }
    }

    private void processKeyEvent(KeyEvent e, boolean pressed) {
        switch (e.getKeyCode()) {
            case KeyEvent.VK_UP:
                renderer.rotateFasterX(pressed);
                break;
            case KeyEvent.VK_DOWN:
                renderer.rotateSlowerX(pressed);
                break;
            case KeyEvent.VK_LEFT:
                renderer.rotateSlowerY(pressed);
                break;
            case KeyEvent.VK_RIGHT:
                renderer.rotateFasterY(pressed);
                break;
            case KeyEvent.VK_PAGE_UP:
                renderer.zoomIn(pressed);
                break;
            case KeyEvent.VK_PAGE_DOWN:
                renderer.zoomOut(pressed);
                break;
        }
    }
}


package demos.nehe.lesson16;

import demos.common.TextureReader;
import javax.media.opengl.GL;
import javax.media.opengl.GLAutoDrawable;
import javax.media.opengl.GLEventListener;
import javax.media.opengl.glu.GLU;

import java.io.IOException;

class Renderer implements GLEventListener {

    private boolean light;  // Lighting ON/OFF

    private float xrot;    // X Rotation
    private float yrot;    // Y Rotation
    private float xspeed;    // X Rotation Speed
    private boolean rotateFasterX;
    private boolean rotateSlowerX;

    private float yspeed;  // Y Rotation Speed
    private boolean rotateFasterY;
    private boolean rotateSlowerY;

    private float z = -5.0f;  // Depth Into The Screen
    private boolean zoomIn;
    private boolean zoomOut;

    private float[] LightAmbient = {0.5f, 0.5f, 0.5f, 1.0f};
    private float[] LightDiffuse = {1.0f, 1.0f, 1.0f, 1.0f};
    private float[] LightPosition = {0.0f, 0.0f, 2.0f, 1.0f};

    private int filter;    // Which Filter To Use  ( new )

    // Storage For Three Types Of Fog ( new )
    private int fogMode[] = {GL.GL_EXP, GL.GL_EXP2, GL.GL_LINEAR};  
    private int fogfilter = 0;    // Which Fog Mode To Use ( new )
    private float fogColor[] = {0.5f, 0.5f, 0.5f, 1.0f}; // Fog Color ( new )

    private int[] textures = new int[3]; // Storage For 3 Textures

    private GLU glu = new GLU();

    public void toggleLighting() {
        light = !light;
    }

    public void switchFilter() {
        filter = (filter + 1) % 3;
    }

    public void switchFogMode() {
        fogfilter = (fogfilter + 1) % 3;
    }

    public void zoomOut(boolean zoom) {
        zoomOut = zoom;
    }

    public void zoomIn(boolean zoom) {
        zoomIn = zoom;
    }

    public void rotateFasterX(boolean rotate) {
        rotateFasterX = rotate;
    }

    public void rotateSlowerX(boolean rotate) {
        rotateSlowerX = rotate;
    }

    public void rotateFasterY(boolean rotate) {
        rotateFasterY = rotate;
    }

    public void rotateSlowerY(boolean rotate) {
        rotateSlowerY = rotate;
    }

    private void loadGLTextures(GL gl, GLU glu) throws IOException {
        
        TextureReader.Texture texture = 
                TextureReader.readTexture("demos/data/images/crate.png");
        
        //Create Nearest Filtered Texture
        gl.glGenTextures(3, textures, 0);
        gl.glBindTexture(GL.GL_TEXTURE_2D, textures[0]);

        gl.glTexParameteri(GL.GL_TEXTURE_2D, GL.GL_TEXTURE_MAG_FILTER, GL.GL_NEAREST);
        gl.glTexParameteri(GL.GL_TEXTURE_2D, GL.GL_TEXTURE_MIN_FILTER, GL.GL_NEAREST);

        gl.glTexImage2D(GL.GL_TEXTURE_2D,
                0,
                3,
                texture.getWidth(),
                texture.getHeight(),
                0,
                GL.GL_RGB,
                GL.GL_UNSIGNED_BYTE,
                texture.getPixels());

        //Create Linear Filtered Texture
        gl.glBindTexture(GL.GL_TEXTURE_2D, textures[1]);
        gl.glTexParameteri(GL.GL_TEXTURE_2D, GL.GL_TEXTURE_MAG_FILTER, GL.GL_LINEAR);
        gl.glTexParameteri(GL.GL_TEXTURE_2D, GL.GL_TEXTURE_MIN_FILTER, GL.GL_LINEAR);

        gl.glTexImage2D(GL.GL_TEXTURE_2D,
                0,
                3,
                texture.getWidth(),
                texture.getHeight(),
                0,
                GL.GL_RGB,
                GL.GL_UNSIGNED_BYTE,
                texture.getPixels());

        gl.glBindTexture(GL.GL_TEXTURE_2D, textures[2]);
        gl.glTexParameteri(GL.GL_TEXTURE_2D, GL.GL_TEXTURE_MAG_FILTER, GL.GL_LINEAR);
        gl.glTexParameteri(GL.GL_TEXTURE_2D, 
                GL.GL_TEXTURE_MIN_FILTER, GL.GL_LINEAR_MIPMAP_NEAREST);

        glu.gluBuild2DMipmaps(GL.GL_TEXTURE_2D,
                3,
                texture.getWidth(),
                texture.getHeight(),
                GL.GL_RGB,
                GL.GL_UNSIGNED_BYTE,
                texture.getPixels());
    }

    public void init(GLAutoDrawable drawable) {
        GL gl = drawable.getGL();

        try {
            loadGLTextures(gl, glu);
        } catch (IOException e) {
            throw new RuntimeException(e);
        }

        gl.glEnable(GL.GL_TEXTURE_2D);              // Enable Texture Mapping
        gl.glShadeModel(GL.GL_SMOOTH);              // Enables Smooth Color Shading

  // This Will Clear The Background Color To Black
        gl.glClearColor(0.5f, 0.5f, 0.5f, 1.0f);    

        gl.glClearDepth(1.0);                       // Enables Clearing Of The Depth Buffer
        gl.glEnable(GL.GL_DEPTH_TEST);              // Enables Depth Testing
        gl.glDepthFunc(GL.GL_LEQUAL);               // The Type Of Depth Test To Do
        
        // Really Nice Perspective Calculations
        gl.glHint(GL.GL_PERSPECTIVE_CORRECTION_HINT, GL.GL_NICEST);   

  // Setup The Ambient Light
        gl.glLightfv(GL.GL_LIGHT1, GL.GL_AMBIENT, LightAmbient, 0);   

  // Setup The Diffuse Light
        gl.glLightfv(GL.GL_LIGHT1, GL.GL_DIFFUSE, LightDiffuse, 0);   

  // Position The Light
        gl.glLightfv(GL.GL_LIGHT1, GL.GL_POSITION, LightPosition, 0); 
        gl.glEnable(GL.GL_LIGHT1);  // Enable Light One
        gl.glFogi(GL.GL_FOG_MODE, fogMode[fogfilter]);  // Fog Mode
        gl.glFogfv(GL.GL_FOG_COLOR, fogColor, 0);  // Set Fog Color
        gl.glFogf(GL.GL_FOG_DENSITY, 0.35f);    // How Dense Will The Fog Be
        gl.glHint(GL.GL_FOG_HINT, GL.GL_DONT_CARE);  // Fog Hint Value
        gl.glFogf(GL.GL_FOG_START, 1.0f);    // Fog Start Depth
        gl.glFogf(GL.GL_FOG_END, 5.0f);      // Fog End Depth
        gl.glEnable(GL.GL_FOG);        // Enables GL.GL_FOG
    }

    private void update() {
        if (zoomOut)
            z -= 0.02f;

        if (zoomIn)
            z += 0.02f;

        if (rotateFasterX)
            xspeed += 0.01f;

        if (rotateSlowerX)
            xspeed -= 0.01f;

        if (rotateFasterY)
            yspeed += 0.01f;

        if (rotateSlowerY)
            yspeed -= 0.01f;
    }

    public void display(GLAutoDrawable drawable) {
        update();
        GL gl = drawable.getGL();

        if (!light)
            gl.glDisable(GL.GL_LIGHTING);
        else
            gl.glEnable(GL.GL_LIGHTING);

        gl.glFogi(GL.GL_FOG_MODE, fogMode[fogfilter]);

        //Clear The Screen And The Depth Buffer
        gl.glClear(GL.GL_COLOR_BUFFER_BIT | GL.GL_DEPTH_BUFFER_BIT);       
        gl.glLoadIdentity();   //Reset The View
        gl.glTranslatef(0.0f, 0.0f, z);

        gl.glRotatef(xrot, 1.0f, 0.0f, 0.0f);
        gl.glRotatef(yrot, 0.0f, 1.0f, 0.0f);

        gl.glBindTexture(GL.GL_TEXTURE_2D, textures[filter]);

        gl.glBegin(GL.GL_QUADS);
        // Front Face
        gl.glNormal3f(0.0f, 0.0f, 1.0f);
        gl.glTexCoord2f(0.0f, 0.0f);
        gl.glVertex3f(-1.0f, -1.0f, 1.0f);
        gl.glTexCoord2f(1.0f, 0.0f);
        gl.glVertex3f(1.0f, -1.0f, 1.0f);
        gl.glTexCoord2f(1.0f, 1.0f);
        gl.glVertex3f(1.0f, 1.0f, 1.0f);
        gl.glTexCoord2f(0.0f, 1.0f);
        gl.glVertex3f(-1.0f, 1.0f, 1.0f);
        // Back Face
        gl.glNormal3f(0.0f, 0.0f, -1.0f);
        gl.glTexCoord2f(1.0f, 0.0f);
        gl.glVertex3f(-1.0f, -1.0f, -1.0f);
        gl.glTexCoord2f(1.0f, 1.0f);
        gl.glVertex3f(-1.0f, 1.0f, -1.0f);
        gl.glTexCoord2f(0.0f, 1.0f);
        gl.glVertex3f(1.0f, 1.0f, -1.0f);
        gl.glTexCoord2f(0.0f, 0.0f);
        gl.glVertex3f(1.0f, -1.0f, -1.0f);
        // Top Face
        gl.glNormal3f(0.0f, 1.0f, 0.0f);
        gl.glTexCoord2f(0.0f, 1.0f);
        gl.glVertex3f(-1.0f, 1.0f, -1.0f);
        gl.glTexCoord2f(0.0f, 0.0f);
        gl.glVertex3f(-1.0f, 1.0f, 1.0f);
        gl.glTexCoord2f(1.0f, 0.0f);
        gl.glVertex3f(1.0f, 1.0f, 1.0f);
        gl.glTexCoord2f(1.0f, 1.0f);
        gl.glVertex3f(1.0f, 1.0f, -1.0f);
        // Bottom Face
        gl.glNormal3f(0.0f, -1.0f, 0.0f);
        gl.glTexCoord2f(1.0f, 1.0f);
        gl.glVertex3f(-1.0f, -1.0f, -1.0f);
        gl.glTexCoord2f(0.0f, 1.0f);
        gl.glVertex3f(1.0f, -1.0f, -1.0f);
        gl.glTexCoord2f(0.0f, 0.0f);
        gl.glVertex3f(1.0f, -1.0f, 1.0f);
        gl.glTexCoord2f(1.0f, 0.0f);
        gl.glVertex3f(-1.0f, -1.0f, 1.0f);
        // Right face
        gl.glNormal3f(1.0f, 0.0f, 0.0f);
        gl.glTexCoord2f(1.0f, 0.0f);
        gl.glVertex3f(1.0f, -1.0f, -1.0f);
        gl.glTexCoord2f(1.0f, 1.0f);
        gl.glVertex3f(1.0f, 1.0f, -1.0f);
        gl.glTexCoord2f(0.0f, 1.0f);
        gl.glVertex3f(1.0f, 1.0f, 1.0f);
        gl.glTexCoord2f(0.0f, 0.0f);
        gl.glVertex3f(1.0f, -1.0f, 1.0f);
        // Left Face
        gl.glNormal3f(-1.0f, 0.0f, 0.0f);
        gl.glTexCoord2f(0.0f, 0.0f);
        gl.glVertex3f(-1.0f, -1.0f, -1.0f);
        gl.glTexCoord2f(1.0f, 0.0f);
        gl.glVertex3f(-1.0f, -1.0f, 1.0f);
        gl.glTexCoord2f(1.0f, 1.0f);
        gl.glVertex3f(-1.0f, 1.0f, 1.0f);
        gl.glTexCoord2f(0.0f, 1.0f);
        gl.glVertex3f(-1.0f, 1.0f, -1.0f);
        gl.glEnd();

        xrot += xspeed;
        yrot += yspeed;

    }

    public void reshape(GLAutoDrawable drawable,
                        int xstart,
                        int ystart,
                        int width,
                        int height) {
        GL gl = drawable.getGL();

        height = (height == 0) ? 1 : height;

        gl.glViewport(0, 0, width, height);
        gl.glMatrixMode(GL.GL_PROJECTION);
        gl.glLoadIdentity();

        glu.gluPerspective(45, (float) width / height, .1f, 100);
        gl.glMatrixMode(GL.GL_MODELVIEW);
        gl.glLoadIdentity();
    }

    public void displayChanged(GLAutoDrawable drawable,
                               boolean modeChanged,
                               boolean deviceChanged) {
    }


}