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VDL Documentation

CakesVDL Documentation

Last updated: March 1, 2020

4 Creating an aerial shell cake with arbitrary prefire time

For aerial shells, the prefire time defines the lift time of the shell if the prefire >= 0.5.  The prefire of cakes applies to the first shot of the cake (details here).   If prefire is < 0.5, then it defines the “delay before simulation,” making the launches occur a fraction of a second later than the ignition time.   Cakes of comets or other ground effects will generally have a prefire < 0.5, but cakes of shells will generally have a prefire equal to the lift time of the first shell.  Since changing the prefire of a cake of aerial shells to any value >= 0.5 changes the lift time of its first effect, some people ask, “How can I create a cake of aerial shells with a prefire that I specify without affecting the lift times?”.

 

Would prefire < 0.5 work? (EASIEST ANSWER)

Prefire values < 0.5 do not affect the lift time of the shell, so if you want to change the prefire to a small value, you don’t need to worry.  A prefire < 0.5 results in “normal” lift times and a firing pattern for the cake that begins after a small delay (the prefire) from when the cake is ignited.

 

Add LFT to fix the lift time after setting prefire >= 0.5 (GOOD ANSWER)

Prefire values >= 0.5 define the lift time of the first shell, but if that’s not what you want you can explicitly specify the lift time of the first shell in the cake or any other shell in the cake (or any shell, actually) by adding LFT to the cake’s VDL, as in,

1" 2.0s 10 Shot 1.5 PFT FNR Cake Blue Peony 1.75 LFT

Since the prefire of this cake > 1.5, it would specify the lift time of the first effect in the cake (the Blue Peony), but that effect includes the LFT term to specify its lift time explicitly, which takes precedence.  So in this example, the prefire does not affect the simulation at all.  So why would you care about the prefire?   Notwithstanding the simulation, the prefire determines the delay between the firing system’s ignition time and the “effect time” that the choreographer synchronizes to the music, represented by the little blip on the timeline bar.  In this example, the choreographer might want to synchronize to a time point a little after the break of the first shell, giving the stars a chance to blossom.  By setting the prefire time to 0.25 seconds before the actual lift delay of the shell, the choreographer gives his shells more time to develop.

 

Would the “Delay Default” field work instead? (SOMETIMES THE RIGHT ANSWER)

If your reason for setting the prefire to a value that does not correspond to the shell’s lift time is that you have a long fuse in front of the device, like for example a Pyro-Clock fuse or a Visco fuse on a cake, then the “Delay Default” field in Finale 3D may be better suited to your purpose than “Prefire“.

The Delay Default field in Finale 3D is an external delay between the ignition of the e-match and the ignition of the effect.  The column is normally hidden in the effects window and the script, so click the blue gear menu in the upper right of those windows to unhide it.  In the effects window, the column is called “Delay Default” whereas in the script window it is called “Delay” (the internal column name in the script window is “externalDelay”).  The reason it is called “Delay Default” in the effects view is that when you insert an effect the “Delay Default” is copied by value into the script’s “Delay” field.  Once it is copied into the script, you can edit the Delay in the script on a row-by-row basis, as you might need to do if you were adjusting the length of the delay fuses on an item by item basis in the physical world.  Thus the “Delay” in the script can be different for different occurrences of the same effect.