How do I move my camera in LWJGL?

Question

I am making a game in LWJGL (2) and slick-util (I think).

I am trying to move my map (It is a double int array that uses numbers to get the textures), but my code only moves the first texture to be drawn on the screen (top-left). how can I move ALL of my map at the same time? Here is my code:

package Window;

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

import java.io.FileWriter;
import java.io.IOException;
import java.io.Writer;

import org.lwjgl.input.Keyboard;
import org.lwjgl.opengl.Display;

import controls.TileChanger;
import Functions.renderer;
import Window.GridHandler;

public class Main {

 public static void main(String[] args) {

  renderer.begin();

  int[][] map = {
   {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
   {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
   {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
   {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
   {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
   {0, 0, 0, 0, 1, 0, 1, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
   {0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
   {0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
   {0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
   {0, 0, 0, 0, 1, 0, 1, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
   {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
   {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
   {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
  };

  GridHandler grid = new GridHandler(map);
  TileChanger changer = new TileChanger(grid);

  String mapSave = map.toString();
  float translate_x = 0;
  float translate_y = 0;
  int speed = 5;

  while (!Keyboard.isKeyDown(Keyboard.KEY_Q)) {

   //   while(Keyboard.next()){
   if (Keyboard.getEventKey() == Keyboard.KEY_P && Keyboard.getEventKeyState()) {
    System.out.println(mapSave);

    /*      Writer wr;
            try {
                wr = new FileWriter("map.txt");
                wr.write(mapSave);
                wr.close();
            } catch (IOException e) {
                e.printStackTrace();
            } */
   }
   //   }

   if (Keyboard.isKeyDown(Keyboard.KEY_D)) {
    translate_x += speed;
   }

   if (Keyboard.isKeyDown(Keyboard.KEY_A)) {
    translate_x -= speed;
   }

   if (Keyboard.isKeyDown(Keyboard.KEY_S)) {
    translate_y += speed;
   }

   if (Keyboard.isKeyDown(Keyboard.KEY_W)) {
    translate_y -= speed;
   }

   glClear(GL_COLOR_BUFFER_BIT);

   glPushMatrix();

   glTranslatef(translate_x, translate_y, 0);

   glEnable(GL_TEXTURE_2D);


   changer.Update();

   grid.draw();

   glPopMatrix();

   Display.update();
   Display.sync(60);
  }
  Display.destroy();
  System.exit(0);
 }
}

Can anyone help me out? (I need the map to move correctly when I push any of the WASD keys (W = up, A = left, S = down, D = right).

Answer 1

Translating a camera is the equivalent to translating the world in the opposite direction. In other words, at the very bottom of your matrix stack, your camera's matrix exists. You need to translate this wherever your camera must be in the opposite direction.

If you wish to move up 5 paces. You translate the world down five paces.

This is typically the reason why games abstract away logical positioning, and graphical positioning.

Please see this for more information. https://www.opengl.org/archives/resources/faq/technical/viewing.htm

Answer 2

You need to translate and rotate the entire scene. For example, use the glTranslatef() and glRotatef functions. Obviously the process becomes more complicated when using shader files.

Note this question is answered here: https://stackoverflow.com/questions/23727493/creating-a-camera-class-with-lwjgl

Some more resources (Google search):

https://m.youtube.com/watch?v=OO_yNzAuDe4

https://lwjglgamedev.gitbooks.io/3d-game-development-with-lwjgl/content/chapter8/chapter8.html

https://tutorialedge.net/lwjgl-3-orthographic-camera-tutorial