Pighaus Games Docs

Transitions

Covering a change of shot so the cut is never seen, or freezing the old shot and blending it into the new one. From Blueprint, on a view target change, across a level loading, or on every camera cut in the game.

A transition is an effect played over a change of shot: a camera swap, a teleport, a level loading. It comes in two kinds, and every look is one or the other.

  • A cover

    closes over the old shot completely, the change happens underneath where nobody sees it, and it opens on the new shot. Fades, irises, bars, wipes, shutters, film burns.

  • A blend

    keeps the old shot exactly as it was at the change and carries it into the new one: a crossfade, a blur, a whip pan, a zoom through, a smear.

A cover: Optical Shutter's blades close through the lens, the camera cuts behind them, and they open on the new shot.
A blend: the old shot, frozen at the change, dissolves into the live new one.

From Blueprint#

  • Play Transition.

    Covers, then fires Covered. Do the change there and it reveals the new shot; Finished fires once it has.

  • Set View Target With Transition.

    The same, with the change being the player's view moving to the actor you give it.

  • Open Level With Transition.

    Covers, opens the level, and reveals it once it's loaded. The cover holds through the load, however long it takes.

Each takes the player controller whose view it covers. With split screen, each player has their own.

On every camera cut#

Project Settings > Plugins > Blendable FX > Transition Every Camera Cut plays a transition on any cut nothing else has covered, whatever made it: a camera actor taking over, a Sequencer cut, a teleport. A blend there needs the frame from before the cut, which Keep The Last Frame keeps, at the cost of a copy of every frame. Set Transition For Every Camera Cut gives one player their own, or none, for a cutscene that makes its own cuts.

The handshake underneath#

Every transition is a cover, a cut and a reveal, and the nodes above are this done for you. To drive one yourself, from C++ or Blueprint, use the player's Get Blendable FX:

  • 1

    Begin Transition

    with the effect. It starts covering, and gives back a handle.

  • 2

    Is Ready To Cut

    turns true once the old shot is covered, or frozen for a blend. On Covered fires then too.

  • 3

    Make the change

    , whatever it is, and call Cut with the handle. It reveals the new shot.

  • 4

    On Finished

    fires once it's revealed.

Cancel Transition backs out before the cut: it uncovers the same shot with nothing changed, for when whatever wanted the change no longer does. A transition begun while another is playing takes over from wherever the first had got to, so two never fight.

Go deeperHow a blend gets the old shot

A blend can't show the old shot after the cut unless something kept it, so at Begin Transition the render pass is asked to keep the next finished frame, and Is Ready To Cut waits for that frame to arrive. From then on the frozen frame is the old shot, and the live picture is the new one. That's why a blend is ready to cut a frame after it begins rather than at once, and why a blend on every camera cut needs Keep The Last Frame: by the time a cut is noticed, the frame before it has gone.

Where next#