Often in 3D applications, like graphing programs and modelling programs, you’ll be able to click somewhere on the screen and drag your mouse around, and the whole scene will rotate around the origin accordingly. I was wondering, what’s the agreed upon math behind this? Has anyone done anything like this before? How should you translate the dragging on the mouse on the screen into rotation around the origin?
Thanks
Left-right = rotation aroud the y-axis.
Up-down = rotation round the x-axis.
Never rotate around the z-axis if possible. It disorientates people.
You keep the camera a fixed distance away, and dragging left or right rotates (“orbits”) the camera around the circle, keeping it pointed at the center. Dragging up or down either tilts the circle (turntable camera) or raises the circle up or down latitudes in a sphere (orbiting camera) depending on the effect you’re going for – a game almost always uses an orbiting camera, otherwise it would clip through the ground, while a modeler will use a turntable camera.
It’s all pretty easy to achieve with gluLookAt, which has several implementations including ones built in to JOGL and LWJGL, and you can probably find a GLSL implementation out there too.
Arcball (and similar) is pretty common.