Sprite Sheets in lwjgl, unable to move?

[kynian]

Hello I’m learning and playing around with LWJGL, and I was following the tutorial by the guy from thecodinguniverse on youtube (specifically episode 29 about how to load from a sprite sheet) and it worked, I got my sprite loaded, and even found out how to get it facing the right way and switching sprites when you press the A key. I’m trying to figure out how I would go about making the sprite move as well. I was looking at other tutorials that made sprites move around (such as the LWGJL rpg tutorial on youtube) and I could easily get the little “player” from that to move, but I cannot seem to get this one to move at all. Here is the code I have so far:

package com.dipndawtz.ld25;

import org.jdom.Document;
import org.jdom.Element;
import org.jdom.JDOMException;
import org.jdom.input.SAXBuilder;
import org.lwjgl.LWJGLException;
import org.lwjgl.input.Keyboard;
import org.lwjgl.opengl.Display;
import org.lwjgl.opengl.DisplayMode;

import com.dipndawtz.ld25.Util.ImageTools;

import java.io.File;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

import static org.lwjgl.opengl.ARBTextureRectangle.GL_TEXTURE_RECTANGLE_ARB;
import static org.lwjgl.opengl.GL11.*;

public class Main {
	private int x;
	private int y;
	private static int posX;
	private static int posY;

	private static final String WINDOW_TITLE = "NecroLock";
	private static final int[] WINDOW_DIMENSIONS = { 640, 480 };

	private static int spritesheet;
	private static Map<String, Sprite> spriteMap = new HashMap<String, Sprite>();
	private static Sprite currentSprite;
	private static final String SPRITESHEET_IMAGE_LOCATION = "res/spritesheet.png";
	private static final String SPRITESHEET_XML_LOCATION = "res/spritesheet.xml";

	public Main() {
		setUpDisplay();
		setUpSpriteSheets();
		setUpStates();
		setUpMatrices();
		enterGameLoop();
		cleanUp(false);
	}

	private static void render() {
		glClear(GL_COLOR_BUFFER_BIT);

		glBindTexture(GL_TEXTURE_RECTANGLE_ARB, spritesheet);

		int x = currentSprite.getX();
		int y = currentSprite.getY();
		int x2 = currentSprite.getX() + currentSprite.getWidth();
		int y2 = currentSprite.getY() + currentSprite.getHeight();
		posX = Display.getWidth() / 2;
		posY = Display.getHeight() / 2;
		int width = currentSprite.getWidth();
		int height = currentSprite.getHeight();
		System.out.println(posX + ", " + posY);
		// 28x42
		glBegin(GL_QUADS);
		glTexCoord2f(x2, y2);
		// glVertex2f(-0.1f, 0.1f);
		glVertex2f(posX, posY);
		glTexCoord2f(x, y2);
		// glVertex2f(-0.1f, -0.1f);
		glVertex2f(posX + width, posY);
		glTexCoord2f(x, y);
		// glVertex2f(0.1f, -0.1f);
		glVertex2f(posX + width, posY + height);
		glTexCoord2f(x2, y);
		// glVertex2f(0.1f, 0.1f);
		glVertex2f(posX, posY + height);
		glEnd();

		glBindTexture(GL_TEXTURE_RECTANGLE_ARB, 0);
	}

	private static void logic() {

	}

	private void input() {

		if (Keyboard.isKeyDown(Keyboard.KEY_A)) {
			currentSprite = spriteMap.get("fl.png");

		}

	}

	private static void cleanUp(boolean asCrash) {
		glDeleteTextures(spritesheet);
		Display.destroy();
		System.exit(asCrash ? 1 : 0);
	}

	private static void setUpMatrices() {
		glMatrixMode(GL_PROJECTION);
		glOrtho(0, 0, 640, 640, -1, 1);
		glMatrixMode(GL_MODELVIEW);
	}

	private static void setUpSpriteSheets() {
		spritesheet = ImageTools.glLoadLinearPNG(SPRITESHEET_IMAGE_LOCATION);
		SAXBuilder builder = new SAXBuilder();
		try {
			Document document = builder.build(new File(SPRITESHEET_XML_LOCATION));
			Element root = document.getRootElement();
			for (Object spriteObject : root.getChildren()) {
				Element spriteElement = (Element) spriteObject;
				String name = spriteElement.getAttributeValue("n");
				int x = spriteElement.getAttribute("x").getIntValue();
				int y = spriteElement.getAttribute("y").getIntValue();
				int w = spriteElement.getAttribute("w").getIntValue();
				int h = spriteElement.getAttribute("h").getIntValue();
				Sprite sprite = new Sprite(name, x, y, w, h);
				spriteMap.put(sprite.getName(), sprite);
			}
		} catch (JDOMException e) {
			e.printStackTrace();
			cleanUp(true);
		} catch (IOException e) {
			e.printStackTrace();
			cleanUp(true);
		}
		currentSprite = spriteMap.get("fc.png");
	}

	private static void setUpStates() {
		glEnable(GL_TEXTURE_RECTANGLE_ARB);
		glEnable(GL_CULL_FACE);
		glCullFace(GL_BACK);
		currentSprite = spriteMap.get("fc.png");
	}

	private static void update() {
		Display.update();
		Display.sync(60);
	}

	private void enterGameLoop() {
		while (!Display.isCloseRequested()) {
			render();
			logic();
			input();
			update();
		}
	}

	private static void setUpDisplay() {
		try {
			Display.setDisplayMode(new DisplayMode(WINDOW_DIMENSIONS[0], WINDOW_DIMENSIONS[1]));
			Display.setTitle(WINDOW_TITLE);
			Display.create();
		} catch (LWJGLException e) {
			e.printStackTrace();
			cleanUp(true);
		}
	}

	public static void main(String[] args) {
		new Main();
	}

}

The imageTools class,

package com.dipndawtz.ld25.Util;

import de.matthiasmann.twl.utils.PNGDecoder;
import org.lwjgl.BufferUtils;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.nio.ByteBuffer;

import static org.lwjgl.opengl.ARBTextureRectangle.GL_TEXTURE_RECTANGLE_ARB;
import static org.lwjgl.opengl.GL11.*;

public class ImageTools {
	public static int glLoadLinearPNG(String location) {
		int texture = glGenTextures();
		glBindTexture(GL_TEXTURE_RECTANGLE_ARB, texture);
		InputStream in = null;
		try {
			in = new FileInputStream(location);
			PNGDecoder decoder = new PNGDecoder(in);
			ByteBuffer buffer = BufferUtils.createByteBuffer(4 * decoder.getWidth() * decoder.getHeight());
			decoder.decode(buffer, decoder.getWidth() * 4, PNGDecoder.Format.RGBA);
			buffer.flip();
			glTexParameteri(GL_TEXTURE_RECTANGLE_ARB, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
			glTexParameteri(GL_TEXTURE_RECTANGLE_ARB, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
			glTexImage2D(GL_TEXTURE_RECTANGLE_ARB, 0, GL_RGBA, decoder.getWidth(), decoder.getHeight(), 0, GL_RGBA, GL_UNSIGNED_BYTE, buffer);
		} catch (FileNotFoundException e) {
			System.err.println("Texture file could not be found.");
			return -1;
		} catch (IOException e) {
			System.err.print("Failed to load the texture file.");
			return -1;
		} finally {
			if (in != null) {
				try {
					in.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
		}
		glBindTexture(GL_TEXTURE_RECTANGLE_ARB, 0);
		return texture;
	}

	public static int glLoadPNG(String location) {
		int texture = glGenTextures();
		glBindTexture(GL_TEXTURE_2D, texture);
		InputStream in = null;
		try {
			in = new FileInputStream(location);
			PNGDecoder decoder = new PNGDecoder(in);
			ByteBuffer buffer = BufferUtils.createByteBuffer(4 * decoder.getWidth() * decoder.getHeight());
			decoder.decode(buffer, decoder.getWidth() * 4, PNGDecoder.Format.RGBA);
			buffer.flip();
			glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
			glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
			glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, decoder.getWidth(), decoder.getHeight(), 0, GL_RGBA, GL_UNSIGNED_BYTE, buffer);
		} catch (FileNotFoundException e) {
			e.printStackTrace();
			return -1;
		} catch (IOException e) {
			e.printStackTrace();
			return -1;
		} finally {
			if (in != null) {
				try {
					in.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
		}
		glBindTexture(GL_TEXTURE_2D, 0);
		return texture;
	}
}

and the sprite class

package com.dipndawtz.ld25;

public final class Sprite {

	private final String name;
	private final int x;
	private final int y;
	private final int w;
	private final int h;

	public Sprite(String name, int x, int y, int w, int h) {
		this.name = name;
		this.x = x;
		this.y = y;
		this.w = w;
		this.h = h;
	}

	@Override
	public boolean equals(Object o) {
		if (this == o)
			return true;
		if (o == null || getClass() != o.getClass())
			return false;

		Sprite sprite = (Sprite) o;

		if (h != sprite.h)
			return false;
		if (w != sprite.w)
			return false;
		if (x != sprite.x)
			return false;
		if (y != sprite.y)
			return false;
		if (name != null ? !name.equals(sprite.name) : sprite.name != null)
			return false;

		return true;
	}

	@Override
	public int hashCode() {
		int result = name != null ? name.hashCode() : 0;
		result = 31 * result + x;
		result = 31 * result + y;
		result = 31 * result + w;
		result = 31 * result + h;
		return result;
	}

	@Override
	public String toString() {
		return "Sprite{" + "name='" + name + '\'' + ", x=" + x + ", y=" + y + ", w=" + w + ", h=" + h + '}';
	}

	public String getName() {
		return new String(name);
	}

	public int getX() {
		return x;
	}

	public int getY() {
		return y;
	}

	public int getWidth() {
		return w;
	}

	public int getHeight() {
		return h;
	}
}

in the commented out lines of Main you can see what code originally got it showing the sprite in the first place, but when I tried to give it a new variable instead of those constants it wouldn’t draw at all. Any help would be appreciated.

[SkyAphid]

That code looks pretty long and I don’t have the time to read it all, but if you need it to move, you can just push the matrix, use loadIdentity and center the sprite at 0,0; then translate to where you want it. Something like this:

glPushMatrix();
glLoadIdentity();
glTranslatef(x,y,1f);
drawSprite(x,y)
glPopMatrix();

Have the actual camera in the render/update method move to where you want it and you’ll see the player where he’s been placed. I suggest always doing it like this, because if you translate the matrix to the player so that he’s the center, you’ll have more control over him later with rotations and such.

If it’s in the case of controls:

if (Keyboard.keyDown(Keyboard.KEY_RIGHT) x++;

If that’s not the problem, and you don’t know how to go about animating the sprite itself, try to do something like this:

if (animationNext < 100) animationNext++; else animation++; animationNext = 0;
drawSprite(x,y,animation);

If you elaborate on your problem more I’ll try to be more help, I know this is all basic stuff but I don’t really understand what your problem is.