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VDL Documentation

SimulationsVDL Documentation

Last updated: June 12, 2020

2 VDL timing adjustment terms (PFT, LFT, DLY, DUR, CDS)

The VDL language includes terms to affect the timing of the simulation.

 

Table 1 – VDL terms that affect timing

Term Meaning Explanation Example Scope
PFT Prefire PFT < 0.5 defines delay before simulation;
PFT >= 0.5 defines aerial shell lift time
50mm 1.5 PFT Red Peony Effect
LFT Lift delay Aerial shell lift time (overrides prefire) 50mm 1.5 PFT 1.75 LFT Red Peony Shot
DLY Delay before simulation A delay from ignition to when the simulation begins 50mm 10 Shot 10s Cake 2.0 DLY Red Comet Effect
DUR Duration For aerial shells in cakes, the duration of the stars;
For mines and comets in cakes, the duration of the rising effect;
50mm 10 Shot 10s Cake .75 DUR Red Peony Shot part
(applies only in cakes, multi-shot candles, and chains)
CDS Chain delay seconds The delay  between the previous shell and this shell in a chain 3″ 7s Chain of 3 Red Peony + 3.0 CDS White Peony + 4.0 CDS Blue Peony Shot
(applies only in chains)

 

Prefire/PFT

The term “prefire” means the time from firing system ignition to the effect time that is synchronized to the music.  For aerial shells, the prefire is usually associated with the lift time.  In fact, the association is so close that people often use the terms interchangeably.  VDL supports this common usage with the special rules,

PFT < 0.5 defines delay before simulation;
PFT >= 0.5 defines aerial shell lift time

In other words, if the PFT is a small fraction of a second, then it refers to the latency introduced by the firing system or the time it takes for the effect to get started.  If the PFT is in the range that could be a lift time, then that’s what it is.  These rules work almost all the time, so you usually don’t need to give much thought to it.

The rules even work for combination effects like RED PEONY w/ BLUE MINE, or BLUE MINE w/ RED BOMBETTES.  If you want to synchronize the launch of the mine to the music, specify a small prefire < 0.5.  If you want to specify the break of the shell to the music, specify a larger prefire, being the lift time of the shell.

 

LFT and DLY

In circumstances for which the prefire rules are insufficient, the LFT and DLY terms in VDL specify the lift time and delay before simulation, taking precedence over whatever the default lift time would be or whatever the prefire implies.  Consider the case of a bombette roman candle with a 1.0 second fuse prior to the first launch, and then 2.0 seconds between the shots, and finally 3.0 seconds lift time in each of the bombettes.  You can define this effect in VDL as,

50mm 21.0s 4.0 PFT 10 Shot RC 1.0 DLY Pink Peony w/ Green Mine 3.0 LFT

Breaking this phrase apart, you can see the 3.0 LFT time at the end, defining the lift time.  The 1.0 DLY is the delay before simulation, representing the delay before the first launch as the visco fuse works its way down into the roman candle tube to the first shell.  The 4.0 PFT aligns the prefire with the first break, which occurs at 1.0 seconds + 3.0 seconds = 4.0 seconds after the firing system ignition.  What would the choreographer write instead if he wanted to synchronize the music to the launch of the green mine instead of the shell break? (answer: write 1.0 PFT)

 

DUR

The roman candle example illustrates the need for another duration term.   For cakes and multi-shot candles, the duration term in the VDL (21.0s in the roman candle example, above) or in the Duration column in the effect window in Finale 3D defines the shot timing, not the duration of the stars in the shot.  For example, you can specify a RED PEONY with 1.25 second duration stars simply by typing,

1.25s Red Peony

But if you want to include that shell in a cake or candle, you would have no place to put the 1.25s duration specification because the duration in a cake or multi-shot candle VDL would be interpreted as the shot timing specification, namely the time from the first launch to the last break (more details here).  The DUR term in VDL fills the need, as you can see in,

50mm 21.0s 4.0 PFT 10 Shot RC 1.0 DLY Red Peony 1.25 DUR 3.0 LFT

 

CDS

The duration of chains is the first to last shot, so it is easy to write VDL for chains with the same delay between shells.   If a chain has 10 shells, then there are nine delay gaps between the shells (no delay in front of the first), so the overall duration of the chain is 9 times whatever the delay is between the shells.  If the delay is 3 seconds, the chain is 27 seconds long,

100m 27s Chain of 10 Gold Willow

If you want to specify delays individually between the shells so they don’t all have to be the same, you can use the CDS term, as in,

100m 27s Chain of 10 Gold Willow + 4 CDS Green To Blue Ghost Shell + 4 CDS Red Chrysanthemum w/ Green Pistil + 2 CDS Purple Dhalia w/ Crackle Core + 2 CDS Silver Kamuro + 3 CDS Green To Blue Chrysanthemum + 3 CDS Red &amp; Green Atomic Rings + 2 CDS Pink Crossette + 3 CDS Variegated Shell-Of-Shells + 4 CDS Pink Yellow Half-And-Half Shell

 

Figure 1 – Irregularly spaced shells in a chain, as shown on the timeline in Finale 3D.

 

Scope

The scope of the VDL term means how much of the VDL phrase it applies to.  The PFT and DLY apply to the entire effect, even if the effect is a cake or chain, because the entire effect can have only one prefire time and it has only one “delay before simulation”.  Thus you can put the PFT and DLY terms anywhere in a VDL phrase and it doesn’t make any difference.

CDS obviously applies to a single one of the chain shells.  Chains in VDL that are not all the same effect use the plus sign to separate the shots of the chain.  The CDS term applies to the shot that it is in, between the plus signs.

DUR applies only to shots within cakes and candles.  It is not needed for individual effects because the standard duration terminology applies (a number followed by the letter ‘s’).  Within cakes and candles, the DUR applies to the shot part.   The shot part is usually just the shot itself, except for the case of shots that combine mines with comets or shells, in which case the shot part is either the mine or the comet or the shell, not all three together.  Thus you can specify RED PEONY w/ BLUE MINE 1.5 DUR, and the indicated duration applies just to the blue stars of the mine.

You might guess that LFT also applies to the shot part, but it actually applies to the entire shot, because LFT only applies to aerial shells and even shots with multiple parts have only one aerial shell part, so it suffices to put LFT anywhere in the shot.

 

Using LFT to override the prefire on the first shell of shell cake

The prefire of a cake, if at least a half second long, defines the default lift time of the first effect in the cake if that effect is a shell, and does not affect the default lift time of the subsequent effects if they are different (details here).  These mechanics produce the desired result most of the time, but not all the time.  The 11 shot Dahlia cake shown in Figure 2 has a prefire that is not intended to be the lift time of any of the shells, but according to the mechanics of VDL the prefire affects the default lift time of the first shell, making the first shell break on the way up, differently from the other shells.

 

Figure 2 – The prefire of a shell cake affects the lift time of the first shell.

 

The VDL of the cake with the first shell breaking on the way up, shown in Figure 2, is,

30mm 0.6 PFT 11 Shot Cake (a) Red Dahlia w/ Red Tail + (b) Green Dahlia w/ Green Tail + (c) Blue Dahlia w/ Blue Tail + (d) Yellow Dahlia w/ Yellow Tail + (e) Orange Dahlia w/ Orange Tail + (f) Purple Dahlia w/ Purple Tail + (g) Peach Dahlia w/ Peach Tail + (h) Lemon Dahlia w/ Lemon Tail + (i) Aqua Dahlia w/ Aqua Tail + (j) Violet Dahlia w/ Violet Tail + (k) Fuchsia Dahlia w/ Fuchsia Tail, 1 Row (abcdefghijk/FNT)

To fix the lift time of the first shell, simply insert an LFT term for the first shell, as in,

30mm 0.6 PFT 11 Shot Cake (a) 1.6 LFT Red Dahlia w/ Red Tail + (b) Green Dahlia w/ Green Tail + (c) Blue Dahlia w/ Blue Tail + (d) Yellow Dahlia w/ Yellow Tail + (e) Orange Dahlia w/ Orange Tail + (f) Purple Dahlia w/ Purple Tail + (g) Peach Dahlia w/ Peach Tail + (h) Lemon Dahlia w/ Lemon Tail + (i) Aqua Dahlia w/ Aqua Tail + (j) Violet Dahlia w/ Violet Tail + (k) Fuchsia Dahlia w/ Fuchsia Tail, 1 Row (abcdefghijk/FNT)

The adjusted VDL fixes the lift time, as shown in Figure 3.

 

Figure 3 – Use LFT to fix the lift time if the prefire sets an undesired default lift time.