Exercise 8: A beam that flares and fades

Purpose. To fire a beam between two points that swells, changes colour and fades out.

Every emitter so far began as a Part. Other things can be transformed too, and the procedure does not change: build one, transform it, say when, say how it looks, fire. This exercise transforms a Beam. A Beam does not travel, so it has no Motion section. In its place it has two things a Part does not: a width at each end, and a look that is set along its length.

Before starting

Build an ordinary Beam, as for any Roblox Beam:

• Two Parts a few studs apart, each holding one Attachment.
• One Beam inside either Part, with its Attachment0 and Attachment1 set to the two Attachments, and Width0 and Width1 set to 1.

The Beam shows as a plain band between the two Parts.

Procedure

Steps 1 and 2 repeat earlier exercises.

Step	Control	Action	Result
1	The Beam	Select, then press Transform	The band disappears. The Properties panel shows the Beam’s sections: Emission, Appearance, Blender, Shape, Texture.
2	HUD ▸ Emit button	Press	The band appears for one second and vanishes. The Emit box already reads 1.
3	Properties ▸ Shape ▸ Width0 ▸ ⋯	Press	The graph editor opens with a level line at 1.
4	Graph editor ▸ Presets ▸ the fourth thumbnail, Bell	Click, then press Apply	A message reads Applied: Bell. The line now rises and falls back.
5	Properties ▸ Shape ▸ Width0 ▸ ⋯	Hold Shift and click. In the small menu, click Copy graph.	Nothing visible.
6	Properties ▸ Shape ▸ Width1 ▸ ⋯	Hold Shift and click. In the small menu, click Paste graph.	Width1 now holds the same graph.
7	HUD ▸ Emit button	Press	The beam opens from nothing to full width and closes again, over one second.
8	Properties ▸ Blender	Expand	One block shows, titled State 1.
9	Properties ▸ Blender ▸ + Add State	Press	A second block appears, titled State 2, with Time 1. It has the same colour as State 1.
10	Blender ▸ State 2 ▸ Color box	Enter 255, 60, 30	No change yet.
11	Blender ▸ State 2 ▸ Transparency box	Enter 1	No change yet.
12	HUD ▸ Emit button	Press	The beam opens in its first colour, turns red as it closes, and fades to nothing.

NOTE

A Beam emitter has no Color or Transparency row in its Appearance section. Both are set in the Blender.

CAUTION

With Enabled on, a Beam emitter makes a new beam at its Rate, and each lasts its whole Lifetime. At Rate 10 and Lifetime 1, ten beams lie on top of one another at any moment, each at a different point of its graphs. For one beam that never stops, use Animate mode with Loop, as in Exercise 6.

What the steps did

Transform read the Beam as it stood. Its widths became the Width0 and Width1 graphs. Its colour and transparency became State 1 of the Blender. Its two Attachments were kept, and every beam the emitter fires is drawn between them. A Beam emitter starts with an Emit count of 1, which is why the button worked at step 2.

A preset replaces a graph with a ready shape. Bell rises and falls. The shape is fitted between the lowest and highest values the editor is showing, here 0 and 1.

Shift and ⋯ opens a small menu: Copy graph, Paste graph and Reset default. It carries a graph from one row to another on the same emitter. The copy is forgotten when the selection changes.

The Blender changes the look of the beam over its life. A beam’s colour and transparency are not single values. Each is a gradient that runs along the beam, from one Attachment to the other. A state is one such look, placed at a Time between 0, the start of the beam’s life, and 1, its end. At a state’s Time the beam shows exactly that state. Between two states it shows a smooth blend from the one to the other.

In a state	What it sets
Time	When in the beam’s life this look is reached, from 0 to 1.
Color	The colour along the beam. Type three numbers for one colour, or press ⋯ to draw a gradient from end to end.
Transparency	The transparency along the beam. Type one number, or press ⋯ to draw a graph from end to end.

If the result differs

Symptom	Cause	Action
Nothing shows at step 2	The Beam’s Attachment0 or Attachment1 was not set before Transform.	Set them with Shape ▸ Attachment 0 and Attachment 1, using the * button on each row.
The beam narrows at one end only	Width1 does not hold the graph.	Repeat steps 5 and 6 without changing the selection in between.
Paste graph is dim	The selection changed after the copy.	Repeat step 5.
The beam looks brighter or flatter than before Transform	Transform sets Light Influence to 0, so scene lighting no longer shades the beam.	Enter 1 in Appearance ▸ Light Influence.
A typed Time flashes red	The Time is outside 0 to 1, or another state already has it.	Enter a different Time.

Variations

Change	Result
State 1 ▸ Transparency ▸ ⋯, a graph from 0 to 1	The beam is solid at one Attachment and fades toward the other.
A third state, with State 2 moved to Time 0.3	The beam reaches the second look early and spends the rest of its life changing to the third.
Emission ▸ Lifetime 0.15, HUD ▸ Emit 3	A short, hard flash made of three beams at once.
Texture ▸ Tex. Speed 4 on a Beam with a texture	The texture runs along the beam four times a second.
Mode Animate, Loop on	One beam that plays its graphs and states again and again, with no stacking.

Log

New in this exercise	Transforming a Beam. A preset. Shift and ⋯ to copy a graph. The Blender.
Done before	Transform (Exercises 1, 4, 5 and 6). The Emit button (Exercises 3 and 6). The graph editor and Apply (Exercises 4, 5 and 6).
Carried forward	Nothing. Exercise 9 uses the sparks of Exercise 3 again.