JavaScript Basic Syntax
let x;
let x = 1;
let s = "Hello, World!";
x = 100;
s = "Hello";
ar = [];
ar = [1, 2, 3];
ar = ["A", "B"];
o = { Type: 'car',
x : 100,
y : 200
};
sum = a + b;
avg = (a + b) / 2;
sum = sum + 10;
i++;
i += 2;
Declare variable x
Declare x and initialize it with a numerical value
Declare s and initialize it with a string
Assign number 100 to variable x
Assign string "Hello" to variable s
Assign an empty array to variable ar
Assign an array of 3 numbers to variable ar
Assign and array of 2 strings to variable ar
Assign an inline object to variable o
Variable sum is equal to a + b
Assign an expression to variable avg
Variable sum is increased by 10 (the new sum
becomes the older sum + 10)
Variable i is increased (incremented) by 1
Variable i is incremented by 2
JavaScript Basic Syntax: Variables
if (mouseX < width)
{
}
if (hour < 12)
{
}
else
{
}
if (minute <= 15)
{
}
else if(minute <= 30)
{
}
else
{
}
Executes the block of instructions
between { } if condition is true
Executes the first block of instructi
ons if condition is true
If the first condition is true, then the first
block will be executed and the others not.
… otherwise the second block
If the first condition is not true, the else if
is used to test another condition, and if is
true, the block of that else if is executed.
The block after the last else is executed
only if no other condition was true until
that point.
JavaScript Basic Syntax: if statement
JavaScript Basic Syntax: for loop
Prints numbers from 0 to 4 using a for loop and println
for(let i = 0; i < 5; i++)
{
println(i);
}
Prints numbers from 10 down to 0 using a for loop
for(let i = 10; i >= 0; i--)
{
println(i);
}
Prints even numbers from 0 to 100
for(let i = 0; i <= 100; i+=2)
{
println(i);
}
Print all elements of an array
let ar = [10, 20, 30];
for(let element of ar)
{
println(element);
}
0
1
2
3
4
10
9
8
7
6
5
4
3
2
1
0
0
2
4
…
100
10
20
30
Print numbers from 0 to 9 using a while loop
let i = 0;
while(i < 10)
{
println(i);
i++;
}
Print numbers from 0 to 10 using a do while loop
let i = 0;
do
{
println(i);
i++;
}
while(i < 10)
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
do while loop places condition
after the code block, therefore
the block can execute at least
once, even if the condition is
false.
JavaScript Basic Syntax: while / do while
Defining and calling the function balloon
function balloon(x, y, shapeColor)
{
let r = 30;
let stringLen = 100;
fill(shapeColor);
stroke(shapeColor);
circle(x, y, r);
line(x, y + r, x, y + r + stringLen);
}
balloon(100, 100, "red");
balloon(300, 300, "blue");
balloon(500, 200, "yellow");
Functions that return values
function addNumbers(x, y)
{
return x + y;
}
let sum = addNumbers(100, 200);
println(sum);
Function balloon draws a balloon using
simple shapes such as circle and line
It expects as arguments the coordinates
for balloon center and the color of the
balloon
Call function balloon with
different parameters
Call the function and store the
value returned in a variable
JavaScript Basic Syntax: Functions
Print the numbers from 0 to 9
for(let i = 0; i < 10; i++)
{
println(i);
}
println is great for quickly printing
information while learning to code, testing or
debugging programs… or practicing algorithms!
You can use print if you want to print on the same line.
// Returns true if specified number is prime
function isPrime(n)
{
if (n < 2)
return false;
let max = sqrt(n);
for(let i = 2; i <= max; i++)
{
if (n % i === 0)
return false;
}
return true;
}
Print the first 10 prime numbers
let found = 0;
let n = 0;
while(found < 10)
{
if (isPrime(n))
{
println(n);
found++;
}
n++;
}
Printing data
Array Methods
JavaScript Array Methods. Part 1
Declaring and initializing an empty array
let ar = [];
Declaring and initializing an array of 3 numbers
let ar = [10, 20, 30];
Length of an array
let ar = [10, 20, 30];
println(ar.length);
Append an element at the end of the array
let ar = [10, 20, 30];
ar.push(100);
println(ar);
Insert an element at the beginning of an array
let ar = [10, 20, 30];
ar.unshift(1);
println(ar);
Insert an element at an arbitrary position
let ar = [10, 20, 30];
ar.splice(1, 0, 15);
println(ar);
3
[10, 20, 30, 100]
[1, 10, 20, 30]
[10, 15, 20, 30]
After element with position 1, delete
0 elements, and insert number 15
JavaScript Array Methods. Part 2
Read the value of element 2 of an array
let ar = [10, 20, 30];
println(ar[2]);
Calculate the sum of elements of an array
let ar = [10, 20, 30];
let sum = 0;
for(let element of ar)
{
sum += element;
}
println(sum);
Assign a different value to al element of an array
let ar = [10, 20, 30];
ar[2] = 100;
println(ar);
Access the first element
let ar = [10, 20, 30];
println(ar[0]);
Access the last element
let ar = [10, 20, 30];
let len = ar.length;
println(ar[len - 1]);
[10, 20, 100]
30
30
Use a classic for loop to
iterate the elements of the
array and add them to a
sum variable
JavaScript Array Methods. Part 3
Remove the first element of the array
let ar = [10, 20, 30];
ar.shift();
println(ar);
Remove the last element of the array
let ar = [10, 20, 30];
ar.pop();
println(ar);
Remove an element at an arbitrary position
let ar = [10, 20, 30];
// 0 -> element index
// 1 -> number of elements to remove
ar.splice(0, 1);
println(ar);
Remove all elements of an array
let ar = [10, 20, 30];
ar.length = 0;
println(ar);
[20, 30]
[]
[20, 30]
[10, 20]
JavaScript Array Methods. Part 4
Concatenate two arrays
// Merge / concatenate 2 arrays
let ar1 = ["a", "b", "c"];
let ar2 = ["d", "e", "f"];
let ar = ar1.concat(ar2);
println(ar);
Extract a slice of an array
let ar = ["a", "b", "c", "d", "e", "f"];
// Extracting a 'slice' from an array
let arSlice = ar.slice(2, 4);
println(arSlice);
Joining elements of an array in a string
let ar = ["a", "b", "c", "d", "e", "f"];
// Join all elements in a string using separator ;
let s = ar.join(";");
println(s);
“a;b;c;d;e;f”
[“a”, “b”, “c”, “d”, “e”, “f”]
[ “c”, “d”]
Method expects as arguments
the index of the first element
(inclusive) and the index of the
last element (exclusive)
String Methods
JavaScript String Methods. Part 1
Length of a string
let txt = "JavaScript";
println(txt.length);
Iterating all characters of a string
let txt = "JavaScript";
for(let chr of txt)
{
println(chr);
}
Accessing string characters by position
let txt = "JavaScript";
for(let i = 0; i < txt.length; i++)
{
println(txt[i]);
}
10
“J”
‘a”
“v”
“a”
“S”
“c”
“r”
“i“
“p”
“t”
“J”
‘a”
“v”
“a”
“S”
“c”
“r”
“i“
“p”
“t”
Not recommended
for Unicode strings
JavaScript String Methods. Part 2
Converting text to uppercase
let txt = "JavaScript";
txt = txt.toUpperCase();
println(txt);
Converting text to lowercase
let txt = "JavaScript";
txt = txt.toLowerCase();
println(txt);
Determine if the string contains another substring
let txt = "Coding is cool!";
let search = "cool";
if (txt.includes(search))
{
println(search + " was found in " + txt);
}
“JAVASCRIPT”
“javascript”
true
JavaScript String Methods. Part 3
Determine if the string starts with a specified prefix
let txt = "JavaScript is cool!";
let search = "JavaScript";
if (txt.startsWith(search))
{
println(txt + " starts with " + search);
}
Determine if the string ends with a specified suffix
let txt = "JavaScript is cool!";
let search = "!";
if (txt.endsWith(search))
{
println("It is an exclamation!");
}
Find the position of a substring. Search starts at the beginning
let txt = "JavaScript is cool!";
let search = "cool";
let foundAt = txt.indexOf(search);
if (foundAt < 0)
println("Not found!");
else
println("Found at position " + foundAt);
true
true
14
JavaScript String Methods. Part 4
Find the position of a substring. Search starts at specified index.
let txt = "JavaScript is cool! Super cool!";
let search = "cool";
let startAt = 18;
let foundAt = txt.indexOf(search, startAt);
if (foundAt < 0)
println("Not found!");
else
println("Found at position " + foundAt);
Extract a substring from the string
let txt = "JavaScript is cool!";
let index1 = 14;
let index2 = 18;
let txt2 = txt.substring(index1, index2);
println(txt2);
26
“cool”
JavaScript String Methods. Part 5
Remove whitespaces from beginning and end of the string
let txt = " I love coding ! ";
txt = txt.trim();
println("'" + txt + "'");
Remove whitespaces from beginning of the string
let txt = " I love coding ! ";
txt = txt.trimStart();
println("'" + txt + “’”);
Remove whitespaces from the end of the string
let txt = " I love coding ! ";
txt = txt.trimEnd();
println("'" + txt + "'");
“I love coding !”
“I love coding ! ”
“ I love coding !”
JavaScript String Methods. Part 6
Pads the start of the string with another string
let no = 3;
let txt = no.toString(2).padStart(8, '0');
println(txt);
Pads the end of the string with another string
let n1 = "1";
let n2 = "3";
txt = n1 + "." + n2.padEnd(4, '0');
println(txt);
“00000011”
“1.3000”
JavaScript String Methods. Part 7
Codes of characters
let txt = "JavaScript";
for(let chr of txt)
{
// Obtain the Unicode code point value
// ... identical to ASCII code for the range of ASCII values
let code = chr.codePointAt(0);
let line = chr + "\t" + code.toString() + "\t" +
code.toString(16).toUpperCase() + "\t" +
code.toString(2).padStart(7, "0");
println(line);
}
J 74 4A 1001010
a 97 61 1100001
v 118 76 1110110
a 97 61 1100001
S 83 53 1010011
c 99 63 1100011
r 114 72 1110010
i 105 69 1101001
p 112 70 1110000
t 116 74 1110100
JavaScript String Methods. Part 8
Characters from codes
let msg = "73 32 76 79 86 69 32 67 79 68 73 78 71"
let base = 10;
let arMsg = msg.split(" ");
for(let i = 0; i < arMsg.length; i++)
{
if (!arMsg[i])
continue;
let code = parseInt(arMsg[i], base);
// Obtain the character from the Unicode code point
// (the Unicode code point is the same with ASCII code for range of ASCII values)
let chr = String.fromCodePoint(code);
println(chr);
}
I
L
O
V
E
C
O
D
I
N
G
Random Numbers
Random Numbers. Part 1
Random floating-point number between 0 and 1 (1 not included)
// Same as Math.random()
let n = random();
println(n);
Random floating-point number between 0 and n (n not included)
let n = random(100);
println(n);
Random floating-point number between n1 and n2 (n2 not included)
let n = random(-100, 100);
println(n);
Random integer between min and max (both included)
// You can use either randomInt or randomNumber
let n = randomInt(0, 10);
println(n);
Random Numbers. Part 2
Random char between chr1 and chr2 (both included)
function randomChar(chr1, chr2)
let char = randomChar("A", "Z");
println(char);
Random element of an array
let ar = ["J", "a", "v", "a", "S", "c", "r", "i", "p", "t"];
let char = random(ar);
println(char);
Shuffle an array
let ar = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
let ar2 = ar.shuffle();
println(ar2);
Modules
Modules
Main Program
MathUtils
const math = require("MathUtils");
let sum = math.add(2, 3);
let prod = math.prod(3, 4);
println(sum);
println(prod);
function add(a, b)
{
return a + b;
}
function prod(a, b)
{
return a * b;
}
Modules provide encapsulation for code and
data / variables
All functions from a module are
automatically “exported”
Drawing Shapes
Drawing. Shapes
circle(400, 300, 200);
ellipse(400, 300, 300, 200);
rect(400, 300, 300, 200);
line(400, 300, 500, 500);
triangle(400, 100, 200, 400, 600, 500);
arc(400, 300, 300, 200, 0, 180);
point(400, 300);
text('JavaScript', 400, 300);
JavaScript
(400, 300)
200
(400, 300)
300
200
(400, 300)
300
200
(400, 300)
(500, 500)
(200, 400)
(600, 500)
(400, 100)
(400, 300)
(400, 300)
(400, 300)
Drawing. Shape Settings
Set the size of text to 20
textSize(20);
text("JavaScript", 400, 300);
Set "Magenta" as the color to fill shapes
fill('Magenta');
circle(400, 300, 100);
Set "Teal" as the color to draw shapes
stroke('Teal');
circle(400, 300, 100);
Set the line thickness to 2 px
strokeWeight(2);
circle(400, 300, 100);
Draw empty shapes, without fill color
noFill();
circle(400, 300, 100);
Draw shapes without an outline
noStroke();
fill("lightblue");
circle(400, 300, 100);
JavaScript
Drawing. Colors
IndianRed, LightCoral, Salmon, DarkSalmon, LightSalmon, Crimson, Red, FireBrick, DarkRed
Pink, LightPink, HotPink, DeepPink, MediumVioletRed, PaleVioletRed
LightSalmon, Coral, Tomato, OrangeRed, DarkOrange, Orange
Gold, Yellow, LightYellow, LemonChiffon, LightGoldenrodYellow, PapayaWhip, Moccasin, PeachPuff, PaleGoldenrod, Khaki, DarkKhaki
Lavender, Thistle, Plum, Violet, Orchid, Fuchsia, Magenta, MediumOrchid, MediumPurple, RebeccaPurple, BlueViolet, DarkViolet, Dark
Orchid, DarkMagenta, Purple, Indigo, SlateBlue, DarkSlateBlue, MediumSlateBlue
GreenYellow, Chartreuse, LawnGreen, Lime, LimeGreen, PaleGreen, LightGreen, MediumSpringGreen, SpringGreen, MediumSeaGreen,
SeaGreen, ForestGreen, Green, DarkGreen, YellowGreen, OliveDrab, Olive, DarkOliveGreen, MediumAquamarine, DarkSeaGreen, Light
SeaGreen, DarkCyan, Teal
Aqua, Cyan, LightCyan, PaleTurquoise, Aquamarine, Turquoise, MediumTurquoise, DarkTurquoise, CadetBlue, SteelBlue, LightSteelBlue
, PowderBlue, LightBlue, SkyBlue, LightSkyBlue, DeepSkyBlue, DodgerBlue, CornflowerBlue, MediumSlateBlue, RoyalBlue, Blue, Mediu
mBlue, DarkBlue, Navy MidnightBlue
Cornsilk, BlanchedAlmond, Bisque, NavajoWhite, Wheat, BurlyWood, Tan, RosyBrown, SandyBrown, Goldenrod, DarkGoldenrod, Peru,
Chocolate, SaddleBrown, Sienna, Brown, Maroon
White, Snow, HoneyDew, MintCream, Azure, AliceBlue, GhostWhite, WhiteSmoke, SeaShell, Beige, OldLace, FloralWhite, Ivory, Antiqu
eWhite, Lin n, LavenderBlush, MistyRose
Gainsboro, LightGray, Silver, DarkGray, Gray, DimGray, LightSlateGray, SlateGray, DarkSlateGray, Black
Popular colors
Set the color for drawing
noStroke()
stroke(color)
strokeWeight(weight)
Set the color for filling
background(color)
fill(color)
noFill()
Specifying color
- #RRGGBB (red, green,
blue components)
- Predefined color
Animations. Bouncing ball
let x = 400;
let y = 300;
let dx = 1;
let dy = 1;
let speed = 3;
function loop()
{
clear();
circle(x, y, 10);
x += speed * dx;
y += speed * dy;
if (x < 0 || x > width)
dx *= -1;
if (y < 0 || y > height)
dy *= -1;
}
loop is a special function. If defined, will be
automatically invoked up to 60 times / second
Clear the frame
Draw the objects in the frame
(in this case just the ball)
Update state. The next frame that will be
displayed will use these new values.
Holds animation state.
Turtle Graphics
Turtle Graphics. Part 1
home();
pencolor("Red");
pensize(2);
pendown();
penup();
setposition(100, 100);
left(30);
right(30);
Reset the default turtle to home position
Sets to Red the pen color of the default turtle
Sets to 2 the pen size of the default turtle
Put the pen on the paper. The turtle will draw
Raise the pen from the paper. The turtle will
advance but not draw
Move the turtle to an arbitrary position on the
canvas
Turns the default turtle to the left by the
number of specified degrees
Turns the default turtle to the right by 30
degrees
Turtle Graphics. Part 2
setheading(180);
forward(100);
back(100);
let p = position();
println(p[0]);
println(p[1]);
let angle = heading();
println(angle);
let t1 = createTurtle();
let t2 = createTurtle();
t1.pencolor("Red");
t2.pencolor("Blue");
let t = getDefaultTurtle();
t.forward(100);
Sets the turtle heading (direction) to an
arbitrary angle
Moves the turtle forward by number of specified pixels.
The turtle moves in the direction that was previously set with left, right or
setheading. If the pen is on the paper, the turtle will draw.
The turtle moves in the opposite direction than
would move with forward
Retrieve the x and y position of the default
turtle as an array of 2 numbers
Retrieve the default turtle direction in degrees
Working with multiple turtles
Get the default turtle
Handle User Input
Handle User Input. Keyboard Events
function keyPressed()
{
clear();
text(key, 400, 300);
text(keyCode, 400, 320);
}
function keyReleased()
{
clear();
text(key, 400, 300);
text(keyCode, 400, 320);
}
function keyTyped()
{
clear();
text(key, 400, 300);
text(keyCode, 400, 320);
}
keyPressed event. Executes once when a key is
pressed
keyReleased event. Executes when a key is
released
keyTyped event. Executes when a key is typed
execept for special keys
Handle User Input. Mouse Events 1
function mouseClicked()
{
circle(mouseX, mouseY, 10);
}
function mousePressed()
{
stroke("red");
circle(mouseX, mouseY, 10);
}
function mouseReleased()
{
stroke("blue");
circle(mouseX, mouseY, 10);
}
function doubleClicked()
{
circle(mouseX, mouseY, 10);
}
mouseClicked event. Executes once when the
mouse is pressed and released
mousePressed event. Executes once when the
mouse button is pressed
mouseReleased event. Executes when the mouse
button is released
doubleClicked event. Executes when the mouse is
double clicked
Handle User Input. Mouse Events 2
function mouseMoved()
{
line(mouseX, mouseY,
pmouseX, pmouseY);
}
function mouseDragged()
{
line(mouseX, mouseY,
pmouseX, pmouseY);
}
function mouseWheel()
{
}
mouseMoved event. Executes when the mouse is
moved and button is not pressed
mouseDragged event. Executes when the mouse is
moved and a button is pressed
mouseWheel event. Executes when the user uses
the mouse wheel or touchpad
Handle User Input. Keyboard System Variables
noStroke();
text("Press any key to change color", 10, 10);
function loop()
{
let color = keyIsPressed ? "Red" : "Green";
clear();
fill(color);
circle(400, 300, 100);
}
function keyPressed()
{
if (key.toLowerCase() === "s")
{
showScene("Game");
}
}
function keyPressed()
{
let ENTER_KEYCODE = 13;
if (keyCode === ENTER_KEYCODE)
{
showScene("Game");
}
}
Boolean system variable that indicates
if a key is pressed.
System variable containing the last typed key.
System variable containing the code of the last
key pressed.
The following constants can be used instead of a
numeric key code: LEFT_ARROW,
RIGHT_ARROW, UP_ARROW, DOWN_ARROW.
Handle User Input. Mouse System Variables
function loop()
{
let drawColor = mouseButton === LEFT
? "Red" : "Blue";
stroke(drawColor);
if (mouseIsPressed)
line(mouseX, mouseY, pmouseX, pmouseY);
}
System variable containing the pressed
mouse button. It has one of these
values LEFT, RIGHT, CENTER.
Boolean system variable indicating if any
mouse button is pressed
Horizontal
coordinate of the
mouse cursor.
Vertical coordinate of
the mouse cursor.
Previous horizontal
coordinate of the
mouse cursor
Previous vertical
coordinate of the
mouse cursor.
User Input. keyIsDown() / keyWentDown() functions
let shipX = width / 2;
let fireLaser = false;
function loop()
{
if (keyIsDown(LEFT_ARROW))
shipX -= 10;
else if (keyIsDown(RIGHT_ARROW))
shipX += 10;
fireLaser = false;
if (keyWentDown(32)) // SPACE key
fireLaser = true;
draw();
}
function draw()
{
clear();
fill("Magenta");
rect(shipX, height - 40, 100, 20);
if (fireLaser)
{
stroke("Red");
line(shipX + 50, height - 40, shipX + 50, 0);
}
}
Use keyIsDown() function inside the loop() event
to detect if the specified key is pressed. You need
to specify the key code.
The following constants can be used instead of a
numeric key code: LEFT_ARROW,
RIGHT_ARROW, UP_ARROW, DOWN_ARROW.
keyWentDown() is similar to keyIsDown() but
returns true just once per key pressed.
To retrigger the function, the user need to
release the key and press it again.
Game Development
Game Development. Layers
codeguppy.com has a layered drawing architecture. There are up to 5
drawing layers on top of the canvas at any time as shown in the
following diagram.
The engine combines automatically all the layers and displays the
final image on the screen.
Game Development. Background
background('LightBlue’);
background('#008080’);
background('Summer');
Use a popular named color
Use an RGB color
Use an image from library
Game Development. Loading Built-in Sprites
sprite('plane’);
sprite('plane', 400, 200);
sprite('plane', 0.5);
sprite('plane', 400, 150, 0.5);
sprite('plane.shoot', 400, 150, 0.5);
Load and show sprite “plane”
Load and show sprite “plane”
at coordinates (400, 200)
Load and show sprite “plane”
using a 0.5 size scaling factor
Load and show sprite “plane” at
coordinates and scale specified
Load and show the animation
“shoot” of sprite “plane”.
Display is done at coordinates
and scale specified.
Game Development. Loading Custom Sprites
sprite(img`
. . . . . . . . . . . . . . . .
. . . . . . 4 4 5 . . . . . . .
. 8 8 8 8 8 4 4 4 8 8 8 8 8 . .
. . . . . . . f . . . . . . . .
. . . . . 8 8 8 8 8 . . . . . .
. . . . 8 1 1 8 1 1 8 . . . . .
. . . . 8 1 f 8 f 1 8 . . . . .
. . 8 . 8 8 8 2 8 8 8 . 8 . . .
. . 8 8 8 2 8 8 8 2 8 8 8 . . .
. . . . 8 8 2 2 2 8 8 . . . . .
. . . . 8 8 8 8 8 8 8 . . . . .
. . . . 8 8 8 8 8 8 8 . . . . .
. . . . 8 . . . . . 8 . . . . .
. . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . .
`, 10);
Scaling factor
sprite receives an image object as
parameter.
img converts text to an Image object.
16 color
image in
Microsoft
MakeCode
Arcade
format
Game Development. Animated Custom Sprites
// Note: Shark images are from Microsoft MakeCode Arcade
// https://arcade.makecode.com/
let shark1 = img`
. . . . . . . . . . . . . c c f f f . . . . . . . . . . . . . .
. . . . . . . . . . . c c d d b c f . . . . . . . . . . . . . .
. . . . . . . . . . c c d d b b f . . . . . . . . . . . . . . .
. . . . . . . . . . f c c b b c f . . . . . . . . . . . . . . .
. . . . . f f f f f c c c c c c f f . . . . . . . . . c c c . .
. . . f f b b b b b b b c b b b b c f f f . . . . c c b b c . .
. . f b b b b b b b b c b c b b b b c c c f f . c d b b c . . .
f f b b b b b b f f b b c b c b b b c c c c c f c d b b f . . .
f b c b b b 1 1 f f 1 b c b b b b b c c c c c f f b b f . . . .
f b b b 1 1 1 1 1 1 1 1 b b b b b c c c c c c c b b c f . . . .
. f b 1 1 1 3 3 c c 1 1 b b b b c c c c c c c c c c c f . . . .
. . f c c c 3 1 c 1 1 1 b b b c c c c c b d b f f b b c f . . .
. . . f c 1 3 c 1 1 1 c b b b f c d d d d c c . . f b b f . . .
. . . . f c c c 1 1 1 f b d b b c c d c c . . . . . f b b f . .
. . . . . . . . c c c c f c d b b c c . . . . . . . . f f f . .
. . . . . . . . . . . . . f f f f f . . . . . . . . . . . . . .
`;
let shark2 = img`...`;
let shark3 = img`...`;
let shark4 = img`...`;
sprite([shark1, shark2, shark3, shark4], 400, 300, 2);
Array of images for
animation
Define animation frames
Game Development. Custom Sprite with multiple animations
let ship1 = img`
. . . . . . . . . . . . . . . .
8 8 1 . . . . . . . . . . . . .
2 2 2 2 . . . . . . . . . . . .
2 2 2 2 . . 9 9 9 9 . . . . . .
8 8 8 8 8 9 9 9 9 9 9 . . . . .
8 8 8 8 8 9 9 9 9 9 9 9 . . . .
2 2 2 2 2 9 9 9 9 9 9 9 2 . . .
2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 .
. 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2
4 4 4 2 2 2 2 2 2 2 2 2 2 2 2 2
4 4 4 4 2 2 8 8 8 8 8 8 8 2 2 .
4 4 . . . 8 8 8 8 8 8 8 . . . .
. . . . 8 8 8 8 8 8 8 . . . . .
. . . 8 8 8 8 8 8 8 . . . . . .
. . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . .
`;
let ship2 = img`...`;
let shipLand1 = img`...`;
let shipLand2 = img`...`;
let oShip = {
Flying : [ship1, ship2],
LandingDown : [shipLand1],
LandingUp : [shipLand2]
};
sprite(oShip, 40, 100, 3);
Object describing the
custom sprite
Define frames for all the animations
that make up the custom sprite
Game Development. Basic sprite manipulation
let player = sprite('adventure_girl.idle', 400, 300, 0.5);
player.x = 100;
player.y = 100;
let plane = sprite('plane.fly', 0, 100, 0.5);
plane.velocity.x = 1;
plane.mirrorX(-1);
plane.rotation = 30
for(let i = 0; i < 10; i++)
{
let flower = sprite(img`
. . . . . . . . . . . . . . . .
. . . . . . . 5 5 . . . . . . .
. . . . 5 5 . 5 5 . 5 5 . . . .
. . . . 5 5 5 5 5 5 5 5 . . . .
. . 5 5 . 5 f e f e 5 . 5 5 . .
. . 5 5 5 f e f e f e 5 5 5 . .
. . . 5 f e f e f e f e 5 . . .
. 5 5 5 e f e f e f e f 5 5 5 .
`, random(width), random(-height, 0), 3);
flower.velocity.y = random(1, 3);
flower.rotationSpeed = 2;
}
Reference to the sprite object
Change sprite position on the canvas
Move sprite automatically: Instruct the engine to automatically
increase the .x coordinate 1 pixel at a time (per frame)
Flip the sprite on the X axis… and also rotate it 30 degrees
Move and rotates sprites automatically. Instruct the engine to
increase the .y coordinate with a number between 1 and 3,
and also rotate the sprite 2 degrees at a time (per frame).
Game Development. Sprite Groups
let player = sprite('game.happy', 400, 300, 0.5);
let coins = new Group();
for(let i = 0; i < 10; i++)
{
let coin = sprite('coin’,
random(100, 700), random(50, 550), 0.5);
// add coin to the group
coins.add(coin);
}
function loop()
{
player.x = mouseX;
player.y = mouseY;
// check collision against the group
player.collide(coins, onCollision)
}
function onCollision(player, coin)
{
// remove coin from the group
coins.remove(coin);
coin.velocity.y = -10;
coin.life = 100;
}
Create a player sprite
Create a new sprite group
Create 10 sprite coins
… and add all of them to the “coins” group.
Move the player sprite at the mouse coordinates.
Check if the player sprite is colliding with any coin
in the “coins” group, and if yes, invoke the
“onCollision” function
Upon collision, remove the coin from the group and make it
“fly” outside of the screen, 10 pixels at a time … for 100 frames.
Game Development. Music and Sound Effects
music('Fun Background', 0.1);
sound('zap1');
Music file from the built-in library
Plays a music file in a loop at the specified
volume. A new invocation of music
instruction will start the new music file.
Plays a sound effect from the built-in library.
Multiple invocations of sound instruction, will mix and play the
sounds in parallel.
Volume of music
Game Development. The Game Loop
If the game is using only sprites
background('Road');
let p = sprite('adventure_girl.idle', 400, 400, 0.5);
function loop()
{
p.show("idle");
if (keyIsDown(LEFT_ARROW))
{
p.mirrorX(-1);
p.x -= 10;
p.show("run");
}
else if (keyIsDown(RIGHT_ARROW))
{
p.mirrorX(1);
p.x += 10;
p.show("run");
}
}
Inside the game loop, read the user input
(keyboard / mouse) and then update the
game state and sprites properties.
Sprites will automatically redraw
according to thew newly set properties.
If the game is using shapes
background('Field');
textSize(40);
let plane = sprite('plane.fly', 50, 100, 0.3);
let textX = -280;
function loop()
{
textX++;
displayBanner();
plane.x++;
}
function displayBanner()
{
clear();
fill("White");
rect(textX - 10, 80, 250, 50);
fill("Black");
text("Hello, World!", textX, 120);
}
If your game is also using shapes, the
easiest solution is to clear the screen
between each frame, then redraw the
shapes using the new game state.
Game Development. Multi-Scene Games
Code of first scene (e.g. Game Scene)
let data = {
score : 1000,
time : 10,
bonusPoints : 100
}
...
if (won)
showScene("Congrats", data);
Use showScene to transition to a new
scene.
You can also pass optional arguments to
the new scene.
Code of second scene (e.g. Congrats Scene)
background("Teal");
function enter()
{
let data = sceneArgs;
text("Score: " + data.score, 400, 300);
text("Time: " + data.time, 400, 320);
text("Bonus Points: " + data.bonusPoints, 400, 340);
}
Function enter is automatically executed
each time the scene is shown.
Use sceneArgs to retrieve the arguments passed
to the scene by the showScene function.
Game Development. Collisions between arbitrary shapes. Part 1
Detect collision between point and circle
let circleX = 400;
let circleY = 300;
let circleR = 200;
function loop()
{
clear();
let collide = collisionPointCircle(mouseX, mouseY, circleX, circleY, circleR);
stroke(collide ? "red" : "black");
circle(circleX, circleY, circleR);
}
Detect collision between point and line
let lineX1 = 300;
let lineY1 = 400;
let lineX2 = 500;
let lineY2 = 200;
function loop()
{
clear();
let collide = collisionPointLine(mouseX, mouseY, lineX1, lineY1, lineX2, lineY2);
stroke(collide ? "red" : "black");
line(lineX1, lineY1, lineX2, lineY2);
}
collisionPointCircle receives as
arguments the attributes of the point and
the circle
collisionPointLine receives as
arguments the attributes of the point and
the line
Game Development. Collisions between arbitrary shapes. Part 2
Detect collision between a point and a rectangle
let rectX = 250;
let rectY = 200;
let rectWidth = 300;
let rectHeight = 200;
function loop()
{
clear();
let collide = collisionPointRect(mouseX, mouseY, rectX, rectY, rectWidth, rectHeight);
stroke(collide ? "red" : "black");
rect(rectX, rectY, rectWidth, rectHeight);
}
Detect collision between two circles
let circle1R = 50;
let circle2X = 400;
let circle2Y = 300;
let circle2R = 100;
function loop()
{
clear();
let circle1X = mouseX;
let circle1Y = mouseY;
let collide = collisionCircleCircle(circle1X, circle1Y, circle1R, circle2X, circle2Y, circle2R)
stroke(collide ? "red" : "black");
circle(circle1X, circle1Y, circle1R);
circle(circle2X, circle2Y, circle2R);
}
collisionPointRect receives as
arguments the attributes of the point and
the rectangle
collisionCircleCircle receives as
arguments the attributes of the two circles
Game Development. Collisions between arbitrary shapes. Part 3
Detect collision between a circle and a rectangle
let circleR = 50;
let rectX = 250, rectY = 200, rectWidth = 300, rectHeight = 200;
function loop()
{
clear();
let circleX = mouseX;
let circleY = mouseY;
let collide = collisionCircleRect(circleX, circleY, circleR, rectX, rectY, rectWidth, rectHeight)
stroke(collide ? "red" : "black");
circle(circleX, circleY, circleR);
rect(rectX, rectY, rectWidth, rectHeight);
}
Detect collision between two rectangles
let rect1X = 0, rect1Y = 0, rect1Width = 100, rect1Height = 50;
let rect2X = 250, rect2Y = 200, rect2Width = 300, rect2Height = 200;
function loop()
{
clear();
rect1X = mouseX;
rect1Y = mouseY;
let collide = collisionRectRect(rect1X, rect1Y, rect1Width, rect1Height,
rect2X, rect2Y, rect2Width, rect2Height);
stroke(collide ? "red" : "black");
rect(rect1X, rect1Y, rect1Width, rect1Height);
rect(rect2X, rect2Y, rect2Width, rect2Height);
}
collisionCircleRect receives as
arguments the attributes of the circle and
the rectangle
collisionRectRect receives as
arguments the attributes of the two
rectangles
Game Development. Collisions between arbitrary shapes. Part 4
Detect collision between two lines
let x1 = 400;
let y1 = 300;
let x2 = 0;
let y2 = 0;
let x3 = 300;
let y3 = 400;
let x4 = 500;
let y4 = 200;
function loop()
{
clear();
x2 = mouseX;
y2 = mouseY;
let collide = collisionLineLine(x1, y1, x2, y2, x3, y3, x4, y4);
stroke(collide ? "Red" : "Black");
line(x1, y1, x2, y2);
line(x3, y3, x4, y4);
}
function mouseClicked()
{
x1 = mouseX;
y1 = mouseY;
}
collisionLineLine receives as
arguments the attributes of the two lines
Game Development. Collisions between arbitrary shapes. Part 5
Detect collision between a line and a rectangle
let x1 = 400;
let y1 = 300;
let x3 = 350;
let y3 = 250;
let w = 300;
let h = 100;
function loop()
{
clear();
let x2 = mouseX;
let y2 = mouseY;
let v = collisionLineRect(x1, y1, x2, y2, x3, y3, w, h);
stroke(v ? "Red" : "Black");
line(x1, y1, x2, y2);
rect(x3, y3, w, h);
}
function mouseClicked()
{
x1 = mouseX;
y1 = mouseY;
}
collisionLineRect receives as arguments
the attributes of the line and rectangle
Building User Interfaces
Building User Interfaces. Edit Boxes and Buttons
text("Your name", 300, 90);
let nameBox = createEdit(300, 100, 200);
nameBox.onchange = handleNameChange;
text("Comments", 300, 190);
let commentsBox = createEdit(300, 200, 300, 100);
let btn = createButton(505, 100, 60, 20);
btn.text = "Enter";
btn.onclick = handleButtonClick;
function handleNameChange()
{
commentsBox.text = "Your name is " + nameBox.text;
}
function handleButtonClick(sender)
{
commentsBox.text += "\nThe name you typed is " + nameBox.text + "\n";
}
createEdit creates an input box at
coordinates (300, 200) and width of 300 pixels.
The last parameter, the height, is optional. If
missing a single-line input will be created.
createEdit is returning a reference to the edit
box object. You can use the following properties
to manipulate edit box content.
.text .width
.readonly .height
.visible .onchange
createButton creates a button at specified
coordinates and size.
createButton is returning a reference to the
button object. You can use the following
properties to manipulate button.
.text .width
.visible .height
.disabled .onclick
