p5.js Setup

The code inside the p5.js (or q5.js) setup function runs when the program starts. The new Canvas() constructor creates a section of the screen that the program can draw on.

The p5.js draw function is run 60 times per second by default. The background function can be used to fill the canvas with a color each time it is drawn.

Try changing the width and height of the canvas (the numbers inside the Canvas constructor), then restart the example program!

What is a sprite?

A sprite is a ghost!

Video game developers use the word "sprite" to refer to characters, items, or anything else that moves above a background.

The new Sprite() constructor creates a sprite object, which contains variables that define a sprite’s position, size, and appearance.

Try editing the properties of the box and circle sprites in the mini examples below!

Sprite physics

A sprite's collider is used to detect collisions with other sprites. By default, sprites have a 'dynamic' physics collider that allows the sprite to move freely and be affected by gravity.

'static' colliders can't be moved. 'kinematic' colliders can be moved programmatically but not by other sprites. They also won't collide with other kinematic colliders. Setting a sprite's collider type to 'none' removes it from the physics simulation.

The collider type can also be set using the first letter of the collider type name: 'd', 's', 'k', or 'n'.

Click the reload icon on the top right corner of a mini example to replay it!

Sprite movement

Changing a sprite's position teleports it!

Try clicking around this mini-example.

The next example shows what happens if a sprite is teleported every time the p5.js draw function renders a frame.

If you want a sprite to physically interact with other sprites while it's moving, don't teleport it!

All of the other movement methods on this page work by changing the sprite's x and y axis velocities. velocity aka vel is a p5.js Vector, you can use any Vector functions on it.

You may have to restart this example to see the sprite move.

Move the sprite indefinitely by setting its direction and speed.

You can also set a sprite's direction using a direction name such as: 'up', 'down', 'left', 'right', 'upLeft', 'upRight', 'downLeft', 'downRight'.

Note that p5play converts these direction names to their corresponding angle values.

The move function moves a sprite across a fixed distance. The direction and speed of the movement can be specified as parameters to the function or set separately.

The moveTowards function moves a sprite towards a position, at a percentage of the distance to that position.

In this example, the player moves 10% of the distance to the mouse on every p5.js draw call. Its speed, and the force it exerts on the block, is proportional to the distance it moves.

The moveTo function generates an impulse that moves a sprite to a position at a constant speed.

But note that if the sprite is acted on by a force like gravity or bumps into another sprite, its speed and direction will be affected and it may not reach the target position.

Any movement function that accepts an object with x and y properties could instead be called with (x, y) position numbers.

If you want a sprite to follow another sprite, you may be tempted to use moveTo repeatedly, without waiting for the sprite to reach its destination. But for better performance, try using the angleTo function, which gets the angle between a sprite and a position. This angle can be used to change the direction that the sprite moves in.

In this example, the p5.js dist function is used to calculate the distance between the player and its ally.

Hopefully the examples on this page helped you understand some of the movement options available in p5play. But, they're just building blocks for more complex movement patterns.

You'll often need to experiment with them in creative ways to find the best solutions for your game!

Sprite image

sprite.image or sprite.img can be set to a p5.Image or a url path to an image file.

If you need an image to be loaded before your program starts, it's best to use loadImage inside the p5.js preload function.

sprite.scale changes the size of both the sprite's collider and visual appearance. A scale value of 2 doubles the size of the sprite.

Try pressing the left mouse button. When the sprite.debug property is set to true you can see the sprite's physics body collider. You can make the size of the collider different from the size of the image!

Make Pixel Art!

You can use the spriteArt function to create pixel art images for your sprites. It takes a string as input and returns an image. Each character in the string represents the color value of a pixel in the image.

The second input parameter to the spriteArt function is the scale of the image.

The default palette uses default p5.js colors but you can customize the color palette too!

Try it out!

Try creating two sprites using the sprite constructor.

Collisions

On the first frame that a sprite collides with another sprite, the collides function returns true.

While a sprite is colliding with another sprite, the colliding function returns the number of frames the collision has occurred for.

On the first frame after two sprites collided, the collided function returns true.

Overlaps

Sprites collide by default but they can also overlap!

Layer

By default sprites are drawn in the order they were created in. You can change the draw order by editing sprite's .layer property. Sprites with the highest layer value get drawn first.

On the first frame that a sprite overlaps with another sprite, the overlaps function returns true.

While a sprite is overlapping with another sprite, the overlapping function returns the number of frames the overlap has occurred for.

On the first frame after two sprites overlapped, the overlapped function returns true.

Note that physical interactions between sprites, including collisions and overlaps, can't be properly detected when a sprite is teleported, its position is directly changed!

Try it out!

Try making the blue sprite change to red only if it's overlapping with the red sprite.

Note that this example uses custom shades of blue and red by utilizing the p5.js color function.

Switch between overlaps and collides

By default if you check for an overlap between two sprites, they will no longer collide. You can override this by checking for a collision between the sprites.

In this example, pressing the space key temporarily allows the player to ghost through the wall.

Sprite rotation

Directly changing the rotation property of a sprite will teleport it to the specified rotation angle.

Don't teleport a sprite if you want it to physically interact with other sprites while it's rotating!

All of the other rotation methods on this page work by changing the sprite's rotationSpeed.

Use the rotate function to rotate a sprite by an amount.

The optional second parameter is the speed at which the sprite rotates per frame.

Use the rotateTo function to rotate a sprite to an angle. Rotation speed can be given as an optional second parameter.

Alternatively, if the function is given an object with x, y coordinates, the sprite will rotate to face that position. The "facing" angle is the angle that the sprite should be at when facing the target position. Try changing it from 0 to 90. When you click, the long side of the sprite will rotate to face the mouse.

Use the rotateTowards function to rotate a sprite towards an angle or towards facing a position.

The optional second parameter is the tracking speed, a percent of the distance the sprite moves on each frame to the target rotation angle, 0.1 (10%) by default.

Use the offset property to move the sprite's physics body relative to its center.

When sprite.debug is true, the center of the sprite is marked with a small green crosshair. The center point is where the sprite's x and y coordinates are located. It is also the center of rotation.

Movement sequencing

These examples use a Turtle sprite which is just a regular sprite that's green and shaped like a triangle for that classic turtle programming look.

You can use the await keyword inside an async function to wait for a movement to finish before continuing with the next movement. This is useful for making a sprite move in a sequence.

The move, moveTo, rotate, and rotateTo functions all return a Promise that resolves to true when the movement is finished.

But, if the sprite's movement is interrupted by a new movement or a collision that significantly changes the sprite's trajectory, the promise will resolve to false.

Physical attributes

Sprites have physical attributes that affect how they interact with the world. Take a look at the mini-examples to see these attributes in action.

By default, mass is assigned based on the sprite's size. The larger the sprite, the more mass it has. Mass can also be set manually.

Try changing the mass of one of the sprites in this mini-example.

planck Bugs

p5play uses the planck physics engine, which usually outputs realistic looking physical interactions, but it's not perfect.

In this mini-example the ball has a bounciness of 1, so each time the ball bounces it should return to its starting position. However, due to a bug in planck, the ball bounces incrementally higher each time it hits the ground.

Hopefully the bug will be fixed in a future version of planck or p5play, but until then here's a workaround.

The bounciness bug is most noticeable when a collider bounces off a flat surface. Here's a workaround that overrides the ball's y velocity after it collides with the ground.

Also, you may expect friction to affect circle physics colliders, but sadly it doesn't! Use the rotationDrag property instead.

In this example the block's color is red when it is colliding with the moving platform. Although you might expect the block to stay red while being lifted by the platform, it blinks between red and blue.

In real life when a person gets on an elevator and it rises, we would say that person would be colliding with the elevator floor the whole ride.

In planck however, when colliders are displaced by other colliders, they constantly collide and uncollide with each other.

Chain Colliders

There are three different chain modes: vertex, distance, and line.

To use vertex mode, provide the Sprite constructor with an array of vertex arrays. Each vertex array should contain [x, y] coordinates. In these mini-examples the sprite's (x, y) position is highlighted by a small black square.

Try changing the vertexes of the chain sprite in the mini-example to make the ball stay on the floor!

To use distance mode, provide the Sprite constructor an (x, y) position and an array of distance arrays. These arrays should contain [x, y] distances relative to the previous vertex. The (x, y) position will be the first vertex in the chain.

Distance mode is best for creating super long chains.

Try adding 5 distances to make the ground roll up and down on a rocky ground chain.

To use line mode, provide the Sprite constructor an (x,y) position and a list of line lengths and angles. Each angle is relative to the previous line's angle.

It's best to use line mode for small and/or symmetrical chains.

Note that the line mode chain's (x, y) position is located at the average of all its vertices, which may not be a point on the chain.

Try changing the lengths of these lines and their angles!

Polygon Colliders

Regular polyons can be created by providing the Sprite constructor with a side length and the name of the polygon.

Here are the names you can use: triangle, square, pentagon, hexagon, septagon, octagon, enneagon, decagon, hendecagon, and dodecagon.

If the start and end of a chain is at the same point and the resulting shape is convex, it automatically becomes a polygon!

Regardless of whether a sprite is a polygon or a chain, all physics bodies that start and end at the same point have their (x, y) position located at the center of the shape, not at the first vertex. This position is calculated by averaging all of the shape's vertexes.

You can force a convex polygon to be a chain by setting sprite.shape = 'chain'

Regular polygons can be created from a list with the line length, angle, and repeat.

The formula for the angle of a regular polygon is 360 / n, where n is the number of sides. Make that angle negative to orient the polygon with one of its edges on top.

Try making a square shaped chain!

Here's the code for making a regular star with five points.

Note that because the star is a concave shape it can't have a polygon collider.

Try changing the number of points!

Now you can see how the p5play logo was made!

Even closed chains like this one are made of lines and they're empty on the inside. In the example on the p5play homepage, you can see how chain colliders can contain many other sprites inside them!

Note that closed chain colliders aren't so good at being dynamic colliders. This is a limitation of the Box2D physics engine that p5play uses.

Custom draw

Sometimes you won't be able to use pre-drawn animations to get the kind of visual effect you want for a sprite in motion.

Fortunately, you can customize the sprite's draw function and make it display anything you want!

Note that inside the sprite's draw function the center of the sprite is translated to position (0, 0).

This mini example rotates the sprite's ellipse to the direction it's moving and makes the ellipse stretch in that direction proportional to it's speed. Kind of complicated!

Custom Update

You can also define a custom update function for a sprite that runs at the end of the draw loop or when updateSprites is called. You can put any sprite specific behavior you want in there.

scale

Changing sprite.scale will scale the sprite's collider and visual appearance by the specified amount.

Press a number key to see the sprite scale uniformly by that amount.

Press "d" to double the sprite's scale.

Press "x" or "y" to scale the sprite in that direction by a random amount. But note that if the sprite gets scaled unevenly, the image will get distorted and stay that way even when scaled uniformly again.

Combo Colliders

By using the addCollider function you can add multiple colliders to a sprite.

But only use this feature when it's really necessary for gameplay!

Usually if something requires a lot of colliders, like the walls of a maze, you should just create multiple sprites, each with their own collider.

Also, even if a sprite's image is complex, typically a box or circle will be just fine for physics interactions, especially for small sprites.

Yet sometimes, you will truly need to create a sprite with multiple colliders. For example, if you want to model a pinball flipper!