make example cuter

gleam.toml

@@ -2,16 +2,10 @@ name = "p5js_gleam"
 version = "1.0.0"
 target = "javascript"
 
-# Fill out these fields if you intend to generate HTML documentation or publish
-# your project to the Hex package manager.
-#
-description = "A simple game library providing p5.js bindings for Gleam to make basic games and animations"
+description = "A simple game library providing p5.js bindings for Gleam in a functional style to make basic games and animations. Heavily inspired by the Racket library 2htdp/universe"
 licences = ["MIT"]
 repository = { type = "github", user = "Acepie", repo = "p5js_gleam" }
 links = [{ title = "P5.js", href = "https://p5js.org/" }]
-#
-# For a full reference of all the available options, you can have a look at
-# https://gleam.run/writing-gleam/gleam-toml/.
 
 [dependencies]
 gleam_stdlib = "~> 0.34 or ~> 1.0"

src/p5js_gleam.gleam

@@ -4,14 +4,26 @@ import gleam/float
 import gleam/io
 import gleam/list
 
+type Vector {
+  Vector(x: Float, y: Float)
+}
+
+fn add_vectors(a: Vector, b: Vector) -> Vector {
+  Vector(a.x +. b.x, a.y +. b.y)
+}
+
 type Ball {
-  Ball(x: Float, y: Float, dx: Float, dy: Float)
+  Ball(position: Vector, velocity: Vector, color: String)
 }
 
 type WorldState {
   WorldState(balls: List(Ball))
 }
 
+const colors = [
+  "#ffaff3", "#fefefc", "#a6f0fc", "#fffbe8", "#584355", "#292d3e", "#2f2f2f",
+]
+
 const ball_size = 40.0
 
 const ball_speed = 5.0
@@ -28,29 +40,40 @@ fn setup(p: P5) -> WorldState {
 fn draw(p: P5, state: WorldState) -> Nil {
   p5.background(p, 220)
   {
-    use Ball(x, y, _, _) <- list.map(state.balls)
-    p5.ellipse(p, x, y, ball_size *. 2.0, ball_size *. 2.0)
+    use Ball(Vector(x, y), _, color) <- list.map(state.balls)
+    p
+    |> p5.fill(color)
+    |> p5.ellipse(x, y, ball_size *. 2.0, ball_size *. 2.0)
   }
   Nil
 }
 
 fn advance_ball(b: Ball) -> Ball {
-  Ball(b.x +. b.dx, b.y +. b.dy, b.dx, b.dy)
+  Ball(add_vectors(b.position, b.velocity), b.velocity, b.color)
 }
 
 fn flip_ball_x(b: Ball) -> Ball {
-  Ball(b.x -. b.dx *. 2.0, b.y +. b.dy, float.negate(b.dx), b.dy)
+  let Ball(position, velocity, color) = b
+  let new_velocity = Vector(float.negate(velocity.x), velocity.y)
+  let new_position =
+    Vector(position.x -. velocity.x *. 2.0, position.y +. velocity.y)
+  Ball(new_position, new_velocity, color)
 }
 
 fn flip_ball_y(b: Ball) -> Ball {
-  Ball(b.x +. b.dx, b.y -. b.dy *. 2.0, b.dx, float.negate(b.dy))
+  let Ball(position, velocity, color) = b
+  let new_velocity = Vector(velocity.x, float.negate(velocity.y))
+  let new_position =
+    Vector(position.x +. velocity.x, position.y -. velocity.y *. 2.0)
+  Ball(new_position, new_velocity, color)
 }
 
 fn tick(state: WorldState) -> WorldState {
   io.debug(state)
   let balls = {
     use ball <- list.map(state.balls)
-    case ball.x, ball.y {
+    let Ball(Vector(x, y), _, _) = ball
+    case x, y {
       x, _ if x <. 0.0 || x >. screen_width -> flip_ball_x(ball)
       _, y if y <. 0.0 || y >. screen_height -> flip_ball_y(ball)
       _, _ -> advance_ball(ball)
@@ -70,11 +93,21 @@ fn on_mouse(
   y_position: Float,
   state: WorldState,
 ) -> WorldState {
-  io.debug(x_position)
-  io.debug(y_position)
-  state
+  let assert [color, ..] =
+    colors
+    |> list.shuffle()
+
+  let x_speed = case float.random() {
+    x if x <. 0.5 -> ball_speed
+    _ -> float.negate(ball_speed)
+  }
+  let y_speed = case float.random() {
+    x if x <. 0.5 -> ball_speed
+    _ -> float.negate(ball_speed)
+  }
+
   WorldState([
-    Ball(x_position, y_position, ball_speed, ball_speed),
+    Ball(Vector(x_position, y_position), Vector(x_speed, y_speed), color),
     ..state.balls
   ])
 }