Wavelets are emitted from every point on a wave towards all directions is what I read on a book but on another book I read Wavelets are emitted towards the same direction of the wave. And They create a secondary wave front in front of the wave. First of all a wave front is a line and if the wave fronts are emitted to all directions a line cant connect all dots on a sphere so why do we just choose a line that is tangent to the wavelets emitted forwards, that is to the direction of the wave, There would be an infinite amount of such lines. Secondly if the wavelets go towards all directions they must move back too, so a wavelet moving back should be able to cancel a wavelet moving forwards from the previous wave front.
On the same book it also said that the wavelets are a geometric construction that Huygen used to explain the behavior of waves. Does this mean they don't really happen? Plus Its very easy to draw a circle on a paper and explain these behaviors but in 3D if every object emits waves with specific wavelengths (colors) towards all directions Then how come we see distinct objects?