Camera ClearFlags DepthOnly

Questions & Answers
1

When I set camera clearflags to depth only I am expecting to overdraw on top of the previous frame; preserve color buffer from the previous scene.

Instead I am getting just normal scene with grey background.

I want to render the scene over the previous frame because I want to have effect like this :

Is my understanding wrong?

2

Ok this is my new answer to what I think you want to achieve, let me know if I have misunderstood yet again.

Make three duplicates of your “Front Image”.

Number your duplicates from “Duplicate1” to “Duplicate3”.

Alter the z position(probably z, it may be x depending on how your scene is set up) of each one in order so that each one is a fraction below(from the perspective of your camera) the other(this will stop z fighting, where the images are all at an equal height and Unity does not know which one it should render first, causing flicker)

Now put this code in a script and place it on your first Duplicate1 object :

public var oObject_To_Follow : GameObject;
private var fFollow_Speed : float;

function Start() {
    fFollow_Speed = 10.0;
}

function Update () {
    transform.position = Vector3.Lerp(transform.position, oObject_To_Follow.transform.position, Time.deltaTime * fFollow_Speed);
}

Now in the inspector drag your “Front Image” object onto the empty “oObject To Follow” variable of this script.

Now place a copy of the same script on “Duplicate2”. This time drag the “Duplicate1” object onto the empty “oObject To Follow” variable of this script.

Repeat with “Duplicate3”, with “Duplicate2” as the “oObject To Follow” variable of this script.

Now play and hopefully you have an effect like the one you really wanted. You can add as many duplicates as you want.
Please let me know if I have got it right this time, thanks.