Music Video II

Review — where we got to 5 min

Last lesson you built a track out of loops.

• A backing track is play sound [Dance Snare Beat v] until done inside a forever.
• A beat is play sound [Drum Bass1 v] and a wait (0.5) seconds.
• Layers stay together when their waits are doubles of each other.

Quick-fire

Your drum waits 0.5 seconds. If a dancer changes costume every 0.7 seconds, what does the video look like after a minute?

Today’s Topic 3 min

• Dance sprites, whose costumes are the dance
• next costume and wait (0.5) seconds — the same wait as the beat
• change size by (10) as a pulse, and why it must come back
• change [color v] effect by (25) and clear graphic effects

Learning outcome

By the end of this lesson you will be able to:

1. Make a sprite dance in time with a beat you wrote.
2. Make something pulse on the beat and return to the size it started at.
3. Move the stage lights on the beat, and reset them on every green flag.

Learnt — costume, size, colour 27 min

Nobody in a music video walks about. They stay where they are and change. Every one of today’s blocks is a change, and every one of them happens on the beat.

1 · The costumes are the dance

Add Anina Dance and open its Costumes tab. There are thirteen, and they are drawings of one person dancing. You do not have to draw anything.

when flag clicked
forever
  next costume
  wait (0.5) seconds
end
            

2 · A pulse has to come back

Something that grows on the beat feels like it is playing the music. The trap is easy to fall into.

forever
  change size by (10)
  wait (0.5) seconds
end
              

forever
  change size by (20)
  wait (0.25) seconds
  change size by (-20)
  wait (0.25) seconds
end
              

The two waits add up to 0.5, so the pulse takes exactly one beat. Anything that goes up must come back, and the numbers must add up to the beat.

1. Put set size to (100) % at the top of the stack, above the forever.
2. Run it, then press the stop sign mid-pulse.
3. Run it again. The size starts from 100, not from whatever it was left at.

3 · The lights

Looks has a set of graphic effects. The one that looks like stage lighting is color.

when flag clicked
clear graphic effects
forever
  change [color v] effect by (25)
  wait (0.5) seconds
end
            

Basic — put the dancers on the track 25 min

Open your track from last lesson. Add people to it, one at a time.

Step 1 — the first dancer

1. Add Anina Dance. Put her on the left of the stage.
2. Set her size to about 90% so she fits beside the band.
3. Give her the four-block dancing stack, with the same wait as your drum.
4. Play it. She should change on every hit.

Step 2 — the second dancer

1. Add D-Money Dance on the right.
2. Give him the same stack.
3. Add wait (0.25) seconds above his forever, so he is half a beat behind her.
4. Play it. Two dancers, taking turns rather than moving as one.

Step 3 — the pulse

1. On the drum kit, add the up-and-down size stack.
2. Put set size to (100) % above its forever.
3. Play. The kit should breathe with the beat and never grow.

Step 4 — the lights

1. Give each dancer the colour-effect stack.
2. Put clear graphic effects above every forever.
3. Play twice in a row. Both runs should start the same colour.

Step 5 — watch it as a video

1. Press the full-screen button above the Stage.
2. Watch the whole thing for thirty seconds without touching anything.
3. Anything that drifts, grows or changes colour for ever needs a reset at the top.

One dancer, on your beat

Put a dancer of your choosing on the track you wrote last lesson.

• The dancer changes costume in time with your drum.
• It never travels anywhere.
• Two runs in a row look the same.

Two dancers who are not twins

Add a second dancer. The two must be clearly different to watch, without either one falling off the beat.

• Both are in time with the same track.
• One moves on every beat, the other on every second beat.
• Or one starts half a beat later, so they take turns.

The whole stage on one beat

Everything visible should be moving to the same beat: the dancers, the instruments and the lights.

• At least four things changing on the beat.
• Sizes come back, colours reset, nothing runs away.
• Pressing the flag twice gives the same show both times.

when flag clicked
clear graphic effects
set size to (100) %
switch costume to [anina stance v]
forever
  next costume
  change [color v] effect by (25)
  wait (0.5) seconds
end
            

The drop

Seven ordinary beats, and then one that is not. On the eighth, everything happens at once: the dancers go big, the lights jump, a cymbal crashes.

• The drop lands on every eighth beat, not at random.
• At least two things change on the drop that do not change otherwise.
• Everything is back to normal by the next beat.
• It keeps happening for as long as the video runs.

when flag clicked
set size to (100) %
forever
  repeat (7)
    next costume
    wait (0.5) seconds
  end
  play sound [Cymbal Crash v]
  set size to (140) %
  wait (0.5) seconds
  set size to (100) %
end
            

Summary 4 min

Dancing in Scratch is not travelling. It is changing, on a timer.

1. next costume with the beat’s own wait is a dance.
2. A pulse goes up and comes back, and its two waits add up to one beat.
3. change [color v] effect by (25) is the lighting rig.
4. Whatever a loop changes, the set-up above it has to put back.

Dance sprite

A library sprite whose costumes are drawings of one dance.

On the beat

Using the same wait as the music, so changes land on the hits.

Pulse

Grow and shrink back within one beat. It must return, or it runs away.

Graphic effect

Colour, ghost and the rest. Reset them with clear graphic effects.

Next lesson: the video gets a shape — a verse, a chorus, and one sprite telling everybody when to change.