// CamAxes returns the 3 axes that make up the orthonormal basis of the
// camera's right-handed coordinate system.
func (c *Camera) CamAxes() (*geom.Vec3, *geom.Vec3, *geom.Vec3) {
z := c.Eye
z.Sub(&c.At)
z.Norm()
x := geom.Cross(&c.Up, &z)
x.Norm()
// Recompute up, c.Up might not be perpendicular or normalized
y := geom.Cross(&z, x)
return x, y, &z
}
// main creates a new scene with a camera and a triangle, renders the scene,
// draws the result to a window and displays it. The middle point of the
// triangle continuously changes position relative to the current time.
func main() {
win, err := window.NewWindow(1024, 768, "Three Move", true)
if err != nil {
panic(err)
}
defer window.Terminate()
cam := render.NewDefCam()
p := geom.NewTri4(-1, 0, -3, 0, 1, -3, 1, 0, -3)
then := time.Now()
now := time.Now()
for close := false; !close; close = win.ShouldClose() || win.KeyDown(window.KeyQ) {
then = now
now = time.Now()
dt := now.Sub(then)
d := mgeom.Vec3{0, 0, 0}
if win.KeyDown(window.KeyW) {
d.Add(&cam.At)
}
if win.KeyDown(window.KeyS) {
d.Sub(&cam.At)
}
if win.KeyDown(window.KeyA) {
d.Add(mgeom.Cross(&cam.At, &cam.Up))
}
if win.KeyDown(window.KeyD) {
d.Add(mgeom.Cross(&cam.Up, &cam.At))
}
d.Norm()
d.Scale(dt.Seconds())
cam.Eye.Add(&d)
cam.Ar = float64(win.Width()) / float64(win.Height())
t := cam.PerspTransf(win.Width(), win.Height())
q := p.Transf(t)
win.Clear()
q.Draw(win)
win.Update()
}
}