I'm trying to figure out how to use mouse movement and 3d rendering to create a world in which the user can use the mouse to look around as you would in any 1st person game. Eventually I want to get the keyboard working on moving you around too, but I want to get this part right first. So I've set up a class that defines where you, the person, exists in the world. You have x,y,z (cartesian) coordinates that define where in the world you are. You also have two angles that define which way you are looking (azimuth/horizontal and elevation/incline/vertical). I'm definitely a bit rusty on my spherical coordinates, but I've got my program at least kind of working. On each frame I record the distance of the mouse from the center of the screen and then reset the mouse position to the center using the java Robot class. I then use these distances to change the azimuth and elevation angles. So this works, but the mouse movement is not very smooth. Sometimes it seems smooth but then it *randomly* gets very choppy. Help very much appreciated 

zip download from: www.joekur.com/downloads/mouseMove.zip

The important code happens in this class:

2. class FirstPerson {
3.   float dx, dy;
4.   PVector pos;
5.   float elevation, azimuth;
6.   
7.   FirstPerson() {
8.     reset();
9.   }
10.   
11.   void reset() {
12.     dx = 0;
13.     dy = 0;
14.     pos = new PVector(0,0,0);
15.     // we start looking straight down the Y-axis
16.     elevation = 0;
17.     azimuth = PI/2;
18.   }
19.   
20.   void start() {
21.     //noCursor();
22.     int frameX = frame.getX()+width/2; // center of screen
23.     int frameY = frame.getY()+height/2;
24.     robot.mouseMove(frameX, frameY);
25.   }
26.   
27.   void drawReticle() {
28.     stroke(255,150);
29.     strokeWeight(1);
30.     line(width/2, height/2-5, width/2, height/2+5);
31.     line(width/2-5, height/2, width/2+5, height/2);
32.   }
33.   
34.   void update() {
35.     
36.     
37.     // update differential mouse movement this frame
38.     int frameX = frame.getX()+width/2; // center of screen
39.     int frameY = frame.getY()+height/2;
40.     dx = mouseX - width/2;
41.     dy = mouseY - height/2;
42.     if(!frame.isUndecorated()){
43.       dx += 3;
44.       dy += 25;
45.     }
46.     
47.     // reset mouse to center
48.     robot.mouseMove(frameX, frameY);
49.     
50.     // update view angles based on mouse movement
51.     if (dy > 0)
52.       elevation += sqrt(abs(dy)/float(height))/2.0;
53.     else
54.       elevation -= sqrt(abs(dy)/float(height))/2.0;
55.     if (dx > 0)
56.       azimuth -= sqrt(abs(dx)/float(height))/2.0;
57.     else
58.       azimuth += sqrt(abs(dx)/float(height))/2.0;
59.     
60.     elevation = constrain(elevation, -PI/2+0.0001, PI/2-0.0001);
61.     
62.     // change camera position
63.     float lookDist = 1000;
64.     float lookX, lookY, lookZ;
65.     lookX = pos.x + lookDist * cos(elevation) * cos(azimuth);
66.     lookY = pos.y + lookDist * cos(elevation) * sin(azimuth);
67.     lookZ = pos.z + sin(elevation) * lookDist;
68.     println("elv: " + elevation + " az: " + azimuth);
69.     println("x: " + lookX + " y: " + lookY + " z: " + lookZ);
70.     camera(pos.x, pos.y, pos.z,
71.            lookX, lookY, lookZ,
72.            0,     0,     1    );
73.     
74.     println(dx + " " + dy);
75.     
76.     
77.   }
78.   
79.   void stop() {
80.     cursor();
81.   }
82.   
83. }