What is a Group?
In p5play a Group is a collection of and blueprint for sprites with similar traits and behaviors. For example the dots in Pac-Man!
The group.length
property can be used to
check how many sprites are in a group. In this example the while loop condition is true as long as the dots
group has less than 24 sprites.
In the mini example, new dots.Sprite
creates a sprite
that inherits the dots group's color, y position, and diameter. Each dot is assigned a unique x position.
I call this "soft inheritance" because a group acts as a blueprint for new group sprites.
You can access a sprite in a group by index because groups are arrays. You can use any of the standard JavaScript array methods on a group.
Setting a group's property to a different value will affect all the sprites in the group! I call this "dynamic inheritance".
Using movement functions like group.moveTowards
,
will cause all the sprites in a group to move.
Arrow function property setters
In p5play, when you set a sprite property in a group to an arrow function, each new sprite created using that group will use the function to evaluate the property.
When group.amount
gets adjusted, the group will
automatically create or remove sprites to match the set amount.
In this mini example, each gem sprite is assigned a random x and y position.
Group overlap
The overlap function isn't just for handling if two sprites overlap. You can also check if a sprite overlaps with a sprite in a group.
In this mini example the collect function receives as inputs the player and the gem in the gems group that the player sprite is overlapping. That gem gets removed.
You can use the overlap and collide functions on groups as well.
allSprites Group
p5play creates an allSprites
group that contains all the sprites in a sketch.
Indexed arrow function setters
When evaluating a group sprite's property you can even use its index!
i
is the index of the sprite in the group, which is given as an input parameter to group
property
functions when
they are evaluated.
Sub Groups
In this mini example there are two sub groups of the boxes
group: smallBoxes
and bigBoxes
.
New sprites created using the bigBoxes
group will
inherit traits from the boxes
group but
not from the smallBoxes
groups.
The boxes
group contains all the sprites in the
smallBoxes
and bigBoxes
groups.
The group.removeAll
function can be used to remove all the sprites from a group.