In a 3d FPS game, how would I make the forward movement speed the same on a slow computer as on a fast computer?
So I pretty much have a set movement speed, which is 1000.0f for example, and I have dt, which is stated in both codes below. How would I go about doing this?
This is what I had, but the speed of the frames/movement was completely different on my two different computers:
time = Sys.getTime();
dt = (lastTime - time)/1000.0f;
lastTime = time;
This is what I have now (very simple):
dt = 0.003.0f
Here is my full source code before I made the adjustment from above, although I don't think it is better:
package net.game1.game;
import java.awt.event.KeyEvent;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.lwjgl.Sys;
import org.lwjgl.opengl.Display;
import org.lwjgl.opengl.GL11;
import org.lwjgl.util.vector.Vector3f;
import org.lwjgl.input.Keyboard;
import org.lwjgl.input.Mouse;
import org.lwjgl.LWJGLException;
import org.lwjgl.opengl.DisplayMode;
import org.lwjgl.util.glu.GLU;
import org.newdawn.slick.opengl.Texture;
import org.newdawn.slick.opengl.TextureLoader;
//First Person Camera Controller
public class FPCameraController
{
//the texture
private Texture texture;
//3d vector to store the camera's position in
private Vector3f position = null;
//the rotation around the Y axis of the camera
private float yaw = 0.0f;
//the rotation around the X axis of the camera
private float pitch = 0.0f;
//Constructor that takes the starting x, y, z location of the camera
public FPCameraController(float x, float y, float z)
{
//instantiate position Vector3f to the x y z params.
position = new Vector3f(x, y, z);
}
public FPCameraController() { // This is made so the line FPCameraController app = new FPCameraController(); will work
// TODO Auto-generated constructor stub
}
//increment the camera's current yaw rotation
public void yaw(float amount)
{
//increment the yaw by the amount param
yaw += amount;
}
//increment the camera's current yaw rotation
public void pitch(float amount)
{
//increment the pitch by the amount param
pitch += amount;
}
//moves the camera forward relitive to its current rotation (yaw)
public void walkForward(float distance)
{
position.x -= distance * (float)Math.sin(Math.toRadians(yaw));
position.z += distance * (float)Math.cos(Math.toRadians(yaw));
}
//moves the camera backward relitive to its current rotation (yaw)
public void walkBackwards(float distance)
{
position.x += distance * (float)Math.sin(Math.toRadians(yaw));
position.z -= distance * (float)Math.cos(Math.toRadians(yaw));
}
//strafes the camera left relitive to its current rotation (yaw)
public void strafeLeft(float distance)
{
position.x -= distance * (float)Math.sin(Math.toRadians(yaw-90));
position.z += distance * (float)Math.cos(Math.toRadians(yaw-90));
}
//strafes the camera right relitive to its current rotation (yaw)
public void strafeRight(float distance)
{
position.x -= distance * (float)Math.sin(Math.toRadians(yaw+90));
position.z += distance * (float)Math.cos(Math.toRadians(yaw+90));
}
//translates and rotate the matrix so that it looks through the camera
//this dose basic what gluLookAt() does
public void lookThrough()
{
//roatate the pitch around the X axis
GL11.glRotatef(pitch, 1.0f, 0.0f, 0.0f);
//roatate the yaw around the Y axis
GL11.glRotatef(yaw, 0.0f, 1.0f, 0.0f);
//translate to the position vector's location
GL11.glTranslatef(position.x, position.y, position.z);
}
private static boolean gameRunning=true;
private static int targetWidth = 800;
private static int targetHeight = 600;
private void init(){
try {
texture = TextureLoader.getTexture("PNG", new FileInputStream("/Users/jamesyanyuk/Torradin/Includes/Textures/Floor_001.png"));
} catch (IOException ex) {
Logger.getLogger(FPCameraController.class.getName()).log(Level.SEVERE, null, ex);
}
}
private float xrot=0.1f;
private float yrot=0.1f;
private float zrot=0.1f;
/** The texture thatÃs been loaded */
private static void initDisplay(boolean fullscreen){
DisplayMode chosenMode = null;
try {
DisplayMode[] modes = Display.getAvailableDisplayModes();
for (int i=0;i<modes.length;i++) {
if ((modes[i].getWidth() == targetWidth) && (modes[i].getHeight() == targetHeight)) {
chosenMode = modes[i];
break;
}
}
} catch (LWJGLException e) {
Sys.alert("Error", "Unable to determine display modes.");
System.exit(0);
}
// at this point if we have no mode there was no appropriate, let the user know
// and give up
if (chosenMode == null) {
Sys.alert("Error", "Unable to find appropriate display mode.");
System.exit(0);
}
try {
Display.setDisplayMode(chosenMode);
Display.setFullscreen(fullscreen);
Display.setTitle("Secret Title");
Display.create();
}
catch (LWJGLException e) {
Sys.alert("Error","Unable to create display.");
System.exit(0);
}
}
private static boolean initGL(){
GL11.glMatrixMode(GL11.GL_PROJECTION);
GL11.glLoadIdentity();
// Calculate the aspect ratio of the window
GLU.gluPerspective(45.0f,((float)targetWidth)/((float)targetHeight),0.1f,100.0f);
GL11.glMatrixMode(GL11.GL_MODELVIEW);
GL11.glLoadIdentity();
GL11.glEnable(GL11.GL_TEXTURE_2D); // Enable Texture Mapping ( NEW )
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);
return true;
}
public boolean isKeyPressed(int keyCode) {
// apparently, someone at decided not to use standard
// keycode, so we have to map them over:
switch(keyCode) {
case KeyEvent.VK_SPACE:
keyCode = Keyboard.KEY_SPACE;
break;
case KeyEvent.VK_ESCAPE:
keyCode = Keyboard.KEY_ESCAPE;
break;
case KeyEvent.VK_W:
keyCode = Keyboard.KEY_W;
break;
case KeyEvent.VK_A:
keyCode = Keyboard.KEY_A;
break;
case KeyEvent.VK_S:
keyCode = Keyboard.KEY_S;
break;
case KeyEvent.VK_D:
keyCode = Keyboard.KEY_D;
break;
}
return org.lwjgl.input.Keyboard.isKeyDown(keyCode);
}
private void run(){
FPCameraController camera = new FPCameraController(0, 0, 0);
float dx = 0.0f;
float dy = 0.0f;
float dt = 0.0f; //length of frame
float lastTime = 0.0f; // when the last frame was
float time = 0.0f;
float mouseSensitivity = 0.15f;
float movementSpeed = 10.0f; //move 10 units per second
//hide the mouse
Mouse.setGrabbed(true);
while(gameRunning){
update();
render();
Display.update();
//keep looping till the display window is closed the ESC key is down
/*
while (!Display.isCloseRequested() ||
!Keyboard.isKeyDown(Keyboard.KEY_ESCAPE))
{
*/
time = Sys.getTime();
dt = 1000.0f;
lastTime = time;
//distance in mouse movement from the last getDX() call.
dx = Mouse.getDX();
//distance in mouse movement from the last getDY() call.
dy = Mouse.getDY();
//control camera yaw from x movement from the mouse
camera.yaw(dx * mouseSensitivity);
//control camera pitch from y movement from the mouse
camera.pitch(-dy * mouseSensitivity);
//when passing in the distrance to move
//we times the movementSpeed with dt this is a time scale
//so if its a slow frame u move more then a fast frame
//so on a slow computer you move just as fast as on a fast computer
//OVER HERE! What do I do to make the boolean canWalk actually work the right way?
if (Keyboard.isKeyDown(Keyboard.KEY_W))//move forward
{
camera.walkForward(movementSpeed*dt);
System.out.println("Walking Forward!?");
}
if (Keyboard.isKeyDown(Keyboard.KEY_S))//move backwards
{
camera.walkBackwards(movementSpeed*dt);
}
if (Keyboard.isKeyDown(Keyboard.KEY_A))//strafe left
{
camera.strafeLeft(movementSpeed*dt);
}
if (Keyboard.isKeyDown(Keyboard.KEY_D))//strafe right
{
camera.strafeRight(movementSpeed*dt);
}
//set the modelview matrix back to the identity
GL11.glLoadIdentity();
//look through the camera before you draw anything
camera.lookThrough();
//you would draw your scene here.
//draw the buffer to the screen
//Display.update();
//}
// finally check if the user has requested that the display be
// shutdown
if (Display.isCloseRequested()) {
gameRunning = false;
Display.destroy();
System.exit(0);
}
if (Keyboard.isKeyDown(Keyboard.KEY_ESCAPE))
{
Sys.alert("Close","To continue, press ESCAPE on your keyboard or OK on the screen.");
System.exit(0);
}
}
}
private void update(){
xrot+=0.1f;
yrot+=0.1f;
zrot+=0.1f;
}
private void render(){
GL11.glClear(GL11.GL_COLOR_BUFFER_BIT|GL11.GL_DEPTH_BUFFER_BIT);
//GL11.glLoadIdentity();
GL11.glTranslatef(0.0f,0.0f,-5.0f); // Move Into The Screen 5 Units
GL11.glBegin(GL11.GL_QUADS);
texture.bind(); // or GL11.glBind(texture.getTextureID());
// Front Face
GL11.glTexCoord2f(0.0f, 0.0f);
GL11.glVertex3f(-1.0f, -1.0f, 1.0f); // Bottom Left Of The Texture and Quad
GL11.glTexCoord2f(1.0f, 0.0f);
GL11.glVertex3f( 1.0f, -1.0f, 1.0f); // Bottom Right Of The Texture and Quad
GL11.glTexCoord2f(1.0f, 1.0f);
GL11.glVertex3f( 1.0f, 1.0f, 1.0f); // Top Right Of The Texture and Quad
GL11.glTexCoord2f(0.0f, 1.0f);
GL11.glVertex3f(-1.0f, 1.0f, 1.0f); // Top Left Of The Texture and Quad
// Back Face
GL11.glTexCoord2f(1.0f, 0.0f);
GL11.glVertex3f(-1.0f, -1.0f, -1.0f); // Bottom Right Of The Texture and Quad
GL11.glTexCoord2f(1.0f, 1.0f);
GL11.glVertex3f(-1.0f, 1.0f, -1.0f); // Top Right Of The Texture and Quad
GL11.glTexCoord2f(0.0f, 1.0f);
GL11.glVertex3f( 1.0f, 1.0f, -1.0f); // Top Left Of The Texture and Quad
GL11.glTexCoord2f(0.0f, 0.0f);
GL11.glVertex3f( 1.0f, -1.0f, -1.0f); // Bottom Left Of The Texture and Quad
// Top Face
GL11.glTexCoord2f(0.0f, 1.0f);
GL11.glVertex3f(-1.0f, 1.0f, -1.0f); // Top Left Of The Texture and Quad
GL11.glTexCoord2f(0.0f, 0.0f);
GL11.glVertex3f(-1.0f, 1.0f, 1.0f); // Bottom Left Of The Texture and Quad
GL11.glTexCoord2f(1.0f, 0.0f);
GL11.glVertex3f( 1.0f, 1.0f, 1.0f); // Bottom Right Of The Texture and Quad
GL11.glTexCoord2f(1.0f, 1.0f);
GL11.glVertex3f( 1.0f, 1.0f, -1.0f); // Top Right Of The Texture and Quad
// Bottom Face
GL11.glTexCoord2f(1.0f, 1.0f);
GL11.glVertex3f(-1.0f, -1.0f, -1.0f); // Top Right Of The Texture and Quad
GL11.glTexCoord2f(0.0f, 1.0f);
GL11.glVertex3f( 1.0f, -1.0f, -1.0f); // Top Left Of The Texture and Quad
GL11.glTexCoord2f(0.0f, 0.0f);
GL11.glVertex3f( 1.0f, -1.0f, 1.0f); // Bottom Left Of The Texture and Quad
GL11.glTexCoord2f(1.0f, 0.0f);
GL11.glVertex3f(-1.0f, -1.0f, 1.0f); // Bottom Right Of The Texture and Quad
// Right face
GL11.glTexCoord2f(1.0f, 0.0f);
GL11.glVertex3f( 1.0f, -1.0f, -1.0f); // Bottom Right Of The Texture and Quad
GL11.glTexCoord2f(1.0f, 1.0f);
GL11.glVertex3f( 1.0f, 1.0f, -1.0f); // Top Right Of The Texture and Quad
GL11.glTexCoord2f(0.0f, 1.0f);
GL11.glVertex3f( 1.0f, 1.0f, 1.0f); // Top Left Of The Texture and Quad
GL11.glTexCoord2f(0.0f, 0.0f);
GL11.glVertex3f( 1.0f, -1.0f, 1.0f); // Bottom Left Of The Texture and Quad
// Left Face
GL11.glTexCoord2f(0.0f, 0.0f);
GL11.glVertex3f(-1.0f, -1.0f, -1.0f); // Bottom Left Of The Texture and Quad
GL11.glTexCoord2f(1.0f, 0.0f);
GL11.glVertex3f(-1.0f, -1.0f, 1.0f); // Bottom Right Of The Texture and Quad
GL11.glTexCoord2f(1.0f, 1.0f);
GL11.glVertex3f(-1.0f, 1.0f, 1.0f); // Top Right Of The Texture and Quad
GL11.glTexCoord2f(0.0f, 1.0f);
GL11.glVertex3f(-1.0f, 1.0f, -1.0f); // Top Left Of The Texture and Quad
GL11.glEnd();
}
public static void main(String[] args)
{
FPCameraController app = new FPCameraController();
initDisplay(false);
initGL();
app.init();
app.run();
}
}
You may want to check this article on how to write the main game loop: http://www.koonsolo.com/news/dewitters-gameloop/