OpenGL Camera rotation weirdness

Question

I've been working on a small project with FreeGlut and Glew. Now I'm coding a camera system, but there are some things that are simply weird:

In fullscreen mode if the mouse moves in lower area of the screen, camera movements are faster than if camera moves in upper areas.
The camera makes weird movement, always in same direction, a small 8 figure move move.

code:

void MouseOps(int x, int y)
{
    // Changes in mousepositions.  Always same direction and 
    // in lower right corner of monitor faster, for some reason.
    deltaX = x - MousePreviousX;
    deltaY = y - MousePreviousY;

    // Also I didn't bother to put * 360 in next equations, 
    // because it would make the camera  jump for crazy. 
    // resx and resy are screen resolutions. 
    // Endresult should be that camera can 
    // rotate once when mouse moves over screen
    yaw = yaw + (((deltaX / resx)) * deginrad);
    pitch = pitch + (((deltaY / resy)) * deginrad);

    //Check clippings (eg. camera wont end upside down etc.)
    if(yaw >= (2 * pi) || yaw <= (-2 * pi)  )
        yaw = 0;
    if(pitch >= (pi / 2))
        pitch = pi / 2;
    if(pitch <= (pi / -2))
        pitch = pi / -2;

    //Calculate x, y, and z coordinates of unit sphere to look at (r = 1)
    cam_normX = cos(yaw) * sin(pitch); 
    cam_normY = sin(yaw) * sin(pitch);
    cam_normZ = cos(yaw);

    // Current x and y to previous
    int MousePreviousX = x;
    int MousePreviousY = y; 
}

I tried to use this http://en.wikipedia.org/wiki/Spherical_coordinate_system#Cartesian_coordinates system to calculate the point to look at. Then I passed all "cam_norm" variables to

gluLookAt(cam_posX, cam_posY, cam_posZ,
        cam_posX+cam_normX, cam_posY+cam_normY, cam_posZ + cam_normZ,
        cam_upX, cam_upY, cam_upZ);

Why do you declare `MousePreviousX/Y` at the end of the function? They need to be static or global variables to retain their value between function calls. — Nobody moving away from SE, Mar 23 '13 at 20:14
My bad, i actually have them declared twice apparently. I removed those, but weird things didn't go away. Actually, it appears that the camera doesn't move at all. — Nyxeria, Mar 23 '13 at 20:26
You need to be more specific. What do you mean by `it moves, but weirdly`? What is weird about it? Does it move to fast/slow, only in rough steps, in random directions, to infinity and beyond? — Nobody moving away from SE, Mar 24 '13 at 18:34

Nyxeria · Answer 1 · 2013-03-24T10:27:19.847

I don't know why this works but it fixed all problems:

bool isCursorWarping = false;

void MouseOps(int x, int y)
{

    if(isCursorWarping == false){
        // Changes in mousepositions. Always same direction and in lower right corner of monitor faster, for some reason.
        deltaX = x - MousePreviousX;
        deltaY = y - MousePreviousY;

        yaw = yaw + ((((deltaX / resx)) * deginrad) * 360);
        pitch = pitch + ((((deltaY / resy)) * deginrad) * 360);


        //Check clippings (eg. camera wont end upside down etc.)

        if(x >= resx - 1 || y >= resy - 1 || x == 0 || y == 0)
        {
            warpCursor();
            MousePreviousX = resx / 2;
            MousePreviousY = resy / 2; 
        }else{
            MousePreviousX = x;
            MousePreviousY = y; 
        }

        if(yaw >= (2 * pi) || yaw <= (-2 * pi)  )
            yaw = 0;
        if(pitch >= (pi / 2))
            pitch = pi / 2;
        if(pitch <= (pi / -2))
            pitch = pi / -2;


        //Calculate x, y, and z coordinates of unit sphere to look at (r = 1)

        cam_normX = cos(pitch) * cos(yaw); 
        cam_normY = sin(pitch) * sin(yaw);
        cam_normZ = cos(pitch) * sin(yaw);



    }
        // Current x and y to previous and cleanup



        isCursorWarping = false;


}

void warpCursor()
{
    isCursorWarping = true;
    glutWarpPointer(resx / 2, resy / 2);


}

Then I pass the "cam_norm" values to:

gluLookAt(0.0f, 1.0f, 2.0f, 0.0f + cam_normX, 1.0f + cam_normY, 2.0f+ cam_normZ, 0.0f, 0.1f, 0.0f);

OpenGL Camera rotation weirdness

1 Answers1