Exercise 10: An explosion built from layers

Purpose. To fire three emitters together as one effect, and to change the size and the speed of all three at once.

A finished effect is seldom one emitter. An explosion is a flash, a ball of fire and a cloud of smoke, each made separately and timed against the others. The plugin treats a Folder of emitters as one effect: select the Folder, and everything inside it is fired, sized and timed together.

Before starting

Three emitters kept from earlier exercises are in the workspace:

• The pulsing glow from Exercise 6. It will be the flash.
• The flipbook flame from Exercise 5. It will be the fire.
• The growing ball from Exercise 4. It will be the smoke.

Enabled and Loop are off on all three. Move the three Parts to the same spot.

Procedure

Steps 2 to 4 repeat Exercises 2 and 3 on each emitter in turn.

Step	Control	Action	Result
1	Explorer	Make a Folder in the workspace named Explosion and drag the three emitters into it	The three emitters are inside Explosion.
2	The glow	Select. Enter 0.25 for Emission ▸ Lifetime and 0 for Emission ▸ Linger.	No change yet. The flash will last a quarter of a second.
3	The flipbook flame	Select. On the HUD enter 6 for Emit. Enter 60 for Motion ▸ SpreadAngle.	No change yet. The six flames will fan out.
4	The growing ball	Select. On the HUD enter 10 for Emit and 0.15 for Delay. Enter 180 for Motion ▸ SpreadAngle.	No change yet. The ten balls will leave in every direction.
5	Explosion, in the Explorer	Select	The HUD shows the first emitter’s name followed by (+2). The Properties panel shows one section, titled Meshes (3). A value typed there is written to all three.
6	HUD ▸ Emit button	Press	The flash pulses once. Six flames fan out from it at the same instant. The balls follow 0.15 seconds later, in every direction.
7	≡ ▸ Tools ▸ Re: Size/Time	Press	A small panel opens with two tabs, Size and Time.
8	Size tab ▸ slider	Drag to 2.00x	Nothing is kept yet. The next play shows the effect at twice the size.
9	HUD ▸ Emit button	Press	The whole explosion is twice as large and travels twice as far.
10	Size tab ▸ Apply	Press	The new sizes are kept. The slider returns to 1.00x.
11	Time tab ▸ slider	Drag to 0.50x, then press Apply	The new timing is kept.
12	HUD ▸ Emit button	Press	The explosion plays at half speed. Every part of it takes twice as long, and the layers keep their order.

CAUTION

With a Folder selected, a value typed into a HUD box is written to every emitter inside it. To give one layer its own Emit, Delay or Duration, select that emitter alone.

CAUTION

Press Apply before closing the panel or switching to the other tab. A change that has not been applied is thrown away when the tab leaves the screen.

What the steps did

A Folder is a container, and the plugin looks inside it. Selecting the Folder selects every emitter in it, however deep. The Emit button then fires each one with its own Emit, Delay and Duration. A Model or an ordinary Part that holds emitters works the same way.

This is different from the nesting of Exercise 9. A nested emitter is fired by each particle of its parent. Emitters in a Folder are fired side by side, once each, by one press.

	In a Folder	Nested in a RenderTemplate
Fired by	One press of Emit on the Folder	Each particle of the parent
Appears at	Each emitter’s own place	The parent particle
Delay counted from	The press	The moment the parent particle is made

Size multiplies everything measured in studs: particle sizes, speeds, accelerations, spawn positions, beam widths. It leaves angles, times, rates and counts alone. An effect made larger this way keeps its shape, because the distances its particles travel grow with their size.

Time changes how fast the whole effect runs. At 2.00x it runs twice as fast. Lifetimes, delays and durations are halved. Rates and speeds are doubled. Accelerations are adjusted so that every path keeps its shape. At 0.50x it runs at half speed.

Both sliders run from 0.50x to 2.00x. The number above the slider can be typed over for a factor outside that range. Each Apply is one step in Studio’s undo history.

If the result differs

Symptom	Cause	Action
One layer does not fire	Its Emit and Duration are both 0.	Select that emitter alone and enter a number.
Every layer now has the same Delay	A value was typed into the HUD while the Folder was selected.	Select each emitter alone and enter its own value.
A HUD box reads -	The emitters in the Folder hold different values for it.	Leave it as it is.
The glow does not show	Its Mode is no longer Animate.	Set Mode to Animate.
The Size and Time panel folds away	Nothing the plugin can edit is selected.	Select Explosion. The panel returns.

Variations

Change	Result
Add the sparks rocket of Exercise 9 to the Folder	It fires with the rest, and its nested burst goes off at the top.
HUD ▸ auto-emit, with Explosion selected	The whole explosion replays. Select one layer and edit it while the rest keeps playing.
Size 0.50x, Apply	A hand-sized version of the same explosion.
Time 2.00x, Apply	A sharp, fast version.
Size tab ▸ Scale Spawn Area on	The emitter Parts themselves are resized too.

Log

New in this exercise	A Folder of emitters fired as one. The Tools menu. Size. Time.
Done before	The Emit and Delay boxes (Exercises 3 and 9). SpreadAngle (Exercises 2 and 4). Lifetime (Exercises 2, 6 and 9). Linger (Exercise 6). The Emit button (Exercises 3, 6, 8 and 9).
Carried forward	Keep Explosion. Later exercises add a screen flash, a sound and a script to it.