/*
* Copyright (c) 2013, Oskar Veerhoek
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
* ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* The views and conclusions contained in the software and documentation are those
* of the authors and should not be interpreted as representing official policies,
* either expressed or implied, of the FreeBSD Project.
*/
package episode_35;
import de.matthiasmann.twl.utils.PNGDecoder;
import org.lwjgl.BufferUtils;
import org.lwjgl.LWJGLException;
import org.lwjgl.input.Keyboard;
import org.lwjgl.input.Mouse;
import org.lwjgl.opengl.Display;
import org.lwjgl.opengl.DisplayMode;
import org.lwjgl.util.glu.GLU;
import utility.EulerCamera;
import utility.ShaderLoader;
import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import static org.lwjgl.opengl.GL11.*;
import static org.lwjgl.opengl.GL20.*;
/**
* A 3D terrain loaded from a height-map and a lookup texture. Press 'L' to reload the shader and texture files. Press
* 'P' to switch between normal, point, and wire-frame mode. Press 'F' to flatten the terrain. Click here for an image:
* https://twitter.com/i/#!/CodingUniverse/media/slideshow?url=pic.twitter.com%2FDgMdZ5jm.
*
* @author Oskar Veerhoek
*/
public class TerrainDemo {
private static final String WINDOW_TITLE = "Terrain!";
private static final int[] WINDOW_DIMENSIONS = {1200, 650};
private static final float ASPECT_RATIO = (float) WINDOW_DIMENSIONS[0] / (float) WINDOW_DIMENSIONS[1];
private static final EulerCamera camera = new EulerCamera.Builder().setPosition(-5.4f, 19.2f,
33.2f).setRotation(30, 61, 0).setAspectRatio(ASPECT_RATIO).setFieldOfView(60).build();
/** The shader program that will use the lookup texture and the height-map's vertex data to draw the terrain. */
private static int shaderProgram;
/** The texture that will be used to find out which colours correspond to which heights. */
private static int lookupTexture;
/** The display list that will contain the height-map's vertex data. */
private static int heightmapDisplayList;
/**
* The points of the height. The first dimension represents the z-coordinate. The second dimension represents the
* x-coordinate. The float value represents the height.
*/
private static float[][] data;
/** Whether the terrain should vary in height or be displayed on a grid. */
private static boolean flatten = false;
private static void render() {
// Clear the pixels on the screen and clear the contents of the depth buffer (3D contents of the scene)
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
// Reset any translations the camera made last frame update
glLoadIdentity();
// Apply the camera position and orientation to the scene
camera.applyTranslations();
if (flatten) {
glScalef(1, 0, 1);
}
// Render the heightmap using the shaders that are being used
glCallList(heightmapDisplayList);
}
private static void input() {
while (Keyboard.next()) {
if (Keyboard.getEventKeyState()) {
if (Keyboard.isKeyDown(Keyboard.KEY_F)) {
flatten = !flatten;
}
if (Keyboard.getEventKey() == Keyboard.KEY_L) {
// Reload the shaders and the heightmap data.
glUseProgram(0);
glDeleteProgram(shaderProgram);
glBindTexture(GL_TEXTURE_2D, 0);
glDeleteTextures(lookupTexture);
setUpShaders();
setUpHeightmap();
}
if (Keyboard.getEventKey() == Keyboard.KEY_P) {
// Switch between normal mode, point mode, and wire-frame mode.
int polygonMode = glGetInteger(GL_POLYGON_MODE);
if (polygonMode == GL_LINE) {
glPolygonMode(GL_FRONT, GL_FILL);
} else if (polygonMode == GL_FILL) {
glPolygonMode(GL_FRONT, GL_POINT);
} else if (polygonMode == GL_POINT) {
glPolygonMode(GL_FRONT, GL_LINE);
}
}
}
}
if (Mouse.isButtonDown(0)) {
Mouse.setGrabbed(true);
} else if (Mouse.isButtonDown(1)) {
Mouse.setGrabbed(false);
}
if (Mouse.isGrabbed()) {
camera.processMouse(1, 80, -80);
}
camera.processKeyboard(16, 1);
}
private static void setUpHeightmap() {
try {
// Load the heightmap-image from its resource file
BufferedImage heightmapImage = ImageIO.read(new File("res/images/heightmap.bmp"));
// Initialise the data array, which holds the heights of the heightmap-vertices, with the correct dimensions
data = new float[heightmapImage.getWidth()][heightmapImage.getHeight()];
// Lazily initialise the convenience class for extracting the separate red, green, blue, or alpha channels
// an int in the default RGB color model and default sRGB colourspace.
Color colour;
// Iterate over the pixels in the image on the x-axis
for (int z = 0; z < data.length; z++) {
// Iterate over the pixels in the image on the y-axis
for (int x = 0; x < data[z].length; x++) {
// Retrieve the colour at the current x-location and y-location in the image
colour = new Color(heightmapImage.getRGB(z, x));
// Store the value of the red channel as the height of a heightmap-vertex in 'data'. The choice for
// the red channel is arbitrary, since the heightmap-image itself only has white, gray, and black.
data[z][x] = colour.getRed();
}
}
// Create an input stream for the 'lookup texture', a texture that will used by the fragment shader to
// determine which colour matches which height on the heightmap
FileInputStream heightmapLookupInputStream = new FileInputStream("res/images/heightmap_lookup.png");
// Create a class that will give us information about the image file (width and height) and give us the
// texture data in an OpenGL-friendly manner
PNGDecoder decoder = new PNGDecoder(heightmapLookupInputStream);
// Create a ByteBuffer in which to store the contents of the texture. Its size is the width multiplied by
// the height and 4, which stands for the amount of bytes a float is in Java.
ByteBuffer buffer = BufferUtils.createByteBuffer(4 * decoder.getWidth() * decoder.getHeight());
// 'Decode' the texture and store its data in the buffer we just created
decoder.decode(buffer, decoder.getWidth() * 4, PNGDecoder.Format.RGBA);
// Make the contents of the ByteBuffer readable to OpenGL (and unreadable to us)
buffer.flip();
// Close the input stream for the heightmap 'lookup texture'
heightmapLookupInputStream.close();
// Generate a texture handle for the 'lookup texture'
lookupTexture = glGenTextures();
glBindTexture(GL_TEXTURE_2D, lookupTexture);
// Hand the texture data to OpenGL
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, decoder.getWidth(), decoder.getHeight(), 0, GL_RGBA,
GL_UNSIGNED_BYTE, buffer);
} catch (IOException e) {
e.printStackTrace();
}
// Use the GL_NEAREST texture filter so that the sampled texel (texture pixel) is not smoothed out. Usually
// using GL_NEAREST will make the textured shape appear pixelated, but in this case using the alternative,
// GL_LINEAR, will make the sharp transitions between height-colours ugly.
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
// Generate a display list handle for the display list that will store the heightmap vertex data
heightmapDisplayList = glGenLists(1);
// TODO: Add alternative VBO rendering for pseudo-compatibility with version 3 and higher.
glNewList(heightmapDisplayList, GL_COMPILE);
// Scale back the display list so that its proportions are acceptable.
glScalef(0.2f, 0.06f, 0.2f);
// Iterate over the 'strips' of heightmap data.
for (int z = 0; z < data.length - 1; z++) {
// Render a triangle strip for each 'strip'.
glBegin(GL_TRIANGLE_STRIP);
for (int x = 0; x < data[z].length; x++) {
// Take a vertex from the current strip
glVertex3f(x, data[z][x], z);
// Take a vertex from the next strip
glVertex3f(x, data[z + 1][x], z + 1);
}
glEnd();
}
glEndList();
}
private static void setUpShaders() {
shaderProgram = ShaderLoader.loadShaderPair("res/shaders/landscape.vs", "res/shaders/landscape.fs");
glUseProgram(shaderProgram);
// The following call is redundant because the default value is already 0, but illustrates how you would use
// multiple textures
glUniform1i(glGetUniformLocation(shaderProgram, "lookup"), 0);
}
private static void cleanUp(boolean asCrash) {
glUseProgram(0);
glDeleteProgram(shaderProgram);
glDeleteLists(heightmapDisplayList, 1);
glBindTexture(GL_TEXTURE_2D, 0);
glDeleteTextures(lookupTexture);
System.err.println(GLU.gluErrorString(glGetError()));
Display.destroy();
System.exit(asCrash ? 1 : 0);
}
private static void setUpMatrices() {
camera.applyPerspectiveMatrix();
}
private static void setUpStates() {
camera.applyOptimalStates();
glPointSize(2);
// Enable the sorting of shapes from far to near
glEnable(GL_DEPTH_TEST);
// Set the background to a blue sky colour
glClearColor(0, 0.75f, 1, 1);
// Remove the back (bottom) faces of shapes for performance
glEnable(GL_CULL_FACE);
}
private static void update() {
Display.update();
Display.sync(60);
}
private static void enterGameLoop() {
while (!Display.isCloseRequested()) {
render();
input();
update();
}
}
private static void setUpDisplay() {
try {
Display.setDisplayMode(new DisplayMode(WINDOW_DIMENSIONS[0], WINDOW_DIMENSIONS[1]));
Display.setVSyncEnabled(true);
Display.setTitle(WINDOW_TITLE);
Display.create();
} catch (LWJGLException e) {
e.printStackTrace();
cleanUp(true);
}
}
public static void main(String[] args) {
setUpDisplay();
setUpStates();
setUpHeightmap();
setUpShaders();
setUpMatrices();
enterGameLoop();
cleanUp(false);
}
}