Question

I’m using opengl and trying to create a first person camera. All examples use GLUT and I need to get the mouse differential in cocoa. But I’m running into issues which appers to be tied with mouseMoved being called as soon as the mouse is moved (which is to be expected). Is there a way to make this mroe accurate? Or a simialer function like GLUTS glutMouseFunc?

Current attempt:

-(void)mouseMoved:(NSEvent *)event{
        static bool wrap = false;

        if(!wrap){
            NSPoint eventLocation = [event locationInWindow];

            float centerX = self.frame.size.width/2 + [self window].frame.origin.x;
            float centerY = self.frame.size.height/2 + [self window].frame.origin.y;
            CGPoint mousePointCenter = CGPointMake(centerX, centerY);
            CGWarpMouseCursorPosition(mousePointCenter);

            int dx = eventLocation.x - self.frame.size.width/2 ;
            int dy = eventLocation.y - self.frame.size.height/2 ;

            const float mousespeed = 0.001;

            angles.x += dx * mousespeed;
            angles.y += dy * mousespeed;

            if(angles.x < -M_PI)
              angles.x += M_PI * 2;
            else if(angles.x > M_PI)
              angles.x -= M_PI * 2;

            if(angles.y < -M_PI / 2)
              angles.y = -M_PI / 2;
            if(angles.y > M_PI / 2)
              angles.y = M_PI / 2;

            lookat.x = sinf(angles.x) * cosf(angles.y);
            lookat.y = sinf(angles.y);
            lookat.z = cosf(angles.x) * cosf(angles.y);

           CGWarpMouseCursorPosition(mousePointCenter);

          [self setNeedsDisplay:YES];
        }
        else{
            wrap = true;
        }

}

Answer 1

I’m not sure I followed what your code is supposed to be doing, but repeatedly warping the mouse cursor to a center point is rarely the right thing to do.

First, you can use the deltaX and deltaY values of the NSEvent.

Perhaps you want to do CGAssociateMouseAndMouseCursorPosition(false) to disassociate the mouse from the cursor position. When you do that, the on-screen cursor no longer moves with the mouse. You can hide it or reposition it (yes, you’d warp it once in this case). Also, events no longer have changes in their absolute position. But they do still carry delta movement values which reflect the mouse movements.