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how to implement a frist-person camera in OpenGL


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#1 lumia_icy   Members   -  Reputation: 108

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Posted 10 August 2012 - 11:10 PM

I am new here and in OpenGL,I wanna implement a first-person camera in OpenGL, but I dont know how to use mouse movement to change the Camera goal,I found that lots of case move the cursor in the center of the screen every time ,I wanna ask is there any other implementation ?Please show me some examples .Thanks!Posted Image

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#2 peternicholson   Members   -  Reputation: 98

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Posted 11 August 2012 - 06:30 AM

Hi!
This is a version, which is written in Java using the Lightweight Java Game Library! (LWJGL) :
[source lang="java"]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;//First Person Camera Controllerpublic class BasicFPS{ //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 BasicFPS(float x, float y, float z) { //instantiate position Vector3f to the x y z params. position = new Vector3f(x, y, z); } public BasicFPS() { // 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(){ //load textures here and other things } private float xrot=0.1f; private float yrot=0.1f; private float zrot=0.1f; /** The texture that’s 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(){ BasicFPS camera = new BasicFPS(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(); //here is your movement speed, which can be changed to anything dt = 0.0005f; 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); } 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); //HERE IS WHERE YOU BIND A TEXTURE // 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){ BasicFPS main = new BasicFPS(); initDisplay(false); initGL(); main.init(); main.run(); }}[/source]
I hope this will help you!

#3 Lazy Foo   Members   -  Reputation: 1105

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Posted 11 August 2012 - 04:12 PM

I've personally used the solution of treating mouse movements like torque and using the cross product to find out how much it should spin.

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#4 Freya   Members   -  Reputation: 808

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Posted 13 August 2012 - 09:41 AM

Here's a very simple OpenGL example:

FIrst initialize the camera:
CCamera cam;
cam.position = Vector3D<float>(camX, camY, camZ);
cam.lookAt = Vector3D<float>(0.0,0.0,100.0);


Then update scene:
void paintGL() {
  glClearColor(0.6, 0.8, 0.9, 0.0);
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
  glLoadIdentity();

   //Find current orientation
   retning = root->EulerAngle(sensitivity,0,0,root->globalAngle*M_PI/180.0); // Where root is SceneNode
   //Set camera a little bit back
   cam.position = root->pos - retning*10.0;
   //Camera sees at the region before us
   cam.lookAt = root->pos + retning*10.0;
   //Update camera height
   cam.position[2] = cam.position[2] + 100.0;
   cam.lookAt[2] = cam.lookAt[2] + 50.0;
 
   drawScene();
   swapBuffers();
  }

Now, each time you move your mouse, update global angle:
root->globalAngle += sensitivity;
or
root->globalAngle -= sensitivity;

Edited by Freya, 13 August 2012 - 09:42 AM.

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#5 kuramayoko10   Members   -  Reputation: 386

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Posted 13 August 2012 - 10:28 AM

Also remember that the classic OpenGL tutorials are found on the NeHe website.

The one you are looking for is this one.
Programming is an art. Game programming is a masterpiece!

#6 lumia_icy   Members   -  Reputation: 108

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Posted 14 August 2012 - 10:02 AM

Here's a very simple OpenGL example:

FIrst initialize the camera:

CCamera cam;
cam.position = Vector3D<float>(camX, camY, camZ);
cam.lookAt = Vector3D<float>(0.0,0.0,100.0);


Then update scene:
void paintGL() {
  glClearColor(0.6, 0.8, 0.9, 0.0);
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
  glLoadIdentity();

   //Find current orientation
   retning = root->EulerAngle(sensitivity,0,0,root->globalAngle*M_PI/180.0); // Where root is SceneNode
   //Set camera a little bit back
   cam.position = root->pos - retning*10.0;
   //Camera sees at the region before us
   cam.lookAt = root->pos + retning*10.0;
   //Update camera height
   cam.position[2] = cam.position[2] + 100.0;
   cam.lookAt[2] = cam.lookAt[2] + 50.0;

   drawScene();
   swapBuffers();
  }

Now, each time you move your mouse, update global angle:
root->globalAngle += sensitivity;
or
root->globalAngle -= sensitivity;

my question is ..how to use my mouse or how to calculate the move?Posted Image

#7 dpadam450   Members   -  Reputation: 947

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Posted 14 August 2012 - 12:39 PM

my question is ..how to use my mouse or how to calculate the move?

Well the other guys post described that before that post.

#8 Freya   Members   -  Reputation: 808

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Posted 14 August 2012 - 02:47 PM

Event receivers are usually used to track mouse movements. Those are f.ex. QMouseEvent if you are using QT for graphics, SEvent in Irrlicht and so on.

Code samples for Qt (how to use your mouse): http://www.codeprogress.com/cpp/libraries/qt/qtCaptureMouseMove.php

How to calculate the move: use some variable (sensitivity in my example) for rotation angle. F.eks set sensitivity to 5.0 - it means each time you move your mouse, global angle changes with 5 degrees or smth.
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