From c44252a14c892d99c54ad2d575345720e003a964 Mon Sep 17 00:00:00 2001
From: James Turk <dev@jpt.sh>
Date: Sun, 9 Mar 2025 20:52:32 -0500
Subject: [PATCH] dataclock, another take on the clock with Var() instead of
 animate() to keep w/ declarative mode

---
 artworld/index.js       |  1 +
 artworld/shapes.js      |  6 +++++-
 artworld/variables.js   | 32 ++++++++++++++++++++++++++++
 artworld/world.js       | 45 ++++++++++++++++++++++++++++-----------
 examples/dataclock.html | 47 +++++++++++++++++++++++++++++++++++++++++
 5 files changed, 118 insertions(+), 13 deletions(-)
 create mode 100644 artworld/variables.js
 create mode 100644 examples/dataclock.html

diff --git a/artworld/index.js b/artworld/index.js
index c1e4cf4..cebaaef 100644
--- a/artworld/index.js
+++ b/artworld/index.js
@@ -4,3 +4,4 @@ export { Vector2, degToRad, radToDeg } from "./math.js";
 export { Line, Rect, Circle, Arc, Polygon } from "./shapes.js";
 export { Group } from "./drawable.js";
 export { Random } from "./random.js";
+export { Var } from "./variables.js";
diff --git a/artworld/shapes.js b/artworld/shapes.js
index 96e8387..1f4ef0e 100644
--- a/artworld/shapes.js
+++ b/artworld/shapes.js
@@ -1,6 +1,7 @@
 import { Vector2 } from "./math.js";
 import { Drawable } from "./drawable.js";
 import { Random } from "./random.js";
+import { getVal } from "./variables.js";
 
 function makeCopy(Cls, obj, override) {
   // make new object, will be registered with world, but no _parent yet
@@ -32,7 +33,10 @@ export class Line extends Drawable {
 
   draw() {
     artworld.prepareDraw(this);
-    artworld.drawLine(this.worldPos, this.worldPos.add(this._offsetVec));
+    artworld.drawLine(
+      this.worldPos,
+      this.worldPos.add(getVal(this._offsetVec)),
+    );
   }
 
   to(vec) {
diff --git a/artworld/variables.js b/artworld/variables.js
new file mode 100644
index 0000000..dbe5a44
--- /dev/null
+++ b/artworld/variables.js
@@ -0,0 +1,32 @@
+import { artworld } from "./world.js";
+
+export function getVal(x) {
+  return x && x.getValue ? x.getValue() : x;
+}
+
+export class Var {
+  constructor(value) {
+    if (typeof value === "function") {
+      this._updateFunc = value;
+      this._value = this._updateFunc(0);
+    } else {
+      this._value = value;
+      this._updateFunc = null;
+    }
+    artworld.register(this);
+  }
+
+  updateFunc(func) {
+    this._updateFunc = func;
+  }
+
+  update(t) {
+    if (this._updateFunc) {
+      this._value = this._updateFunc(t);
+    }
+  }
+
+  getValue() {
+    return this._value;
+  }
+}
diff --git a/artworld/world.js b/artworld/world.js
index 19cc69c..cdc978c 100644
--- a/artworld/world.js
+++ b/artworld/world.js
@@ -1,9 +1,11 @@
 import { Timer } from "./timer.js";
+import { getVal, Var } from "./variables.js";
 
 export class World {
   constructor() {
     this.ctx = null;
     this.drawables = [];
+    this.variables = [];
     this.backgroundColor = "white";
     this.timer = new Timer();
     this.targetFrameRate = 60;
@@ -25,8 +27,13 @@ export class World {
   }
 
   // TODO rename
-  register(drawable) {
-    this.drawables.push(drawable);
+  register(thing) {
+    if (thing instanceof Var) {
+      this.variables.push(thing);
+    } else {
+      // TODO: check drawable?
+      this.drawables.push(thing);
+    }
   }
 
   draw() {
@@ -44,6 +51,9 @@ export class World {
     for (let d of this.drawables) {
       d.update(this.numTicks);
     }
+    for (let v of this.variables) {
+      v.update(this.numTicks);
+    }
   }
 
   get updatesPerSecond() {
@@ -67,21 +77,21 @@ export class World {
   prepareDraw(drawable) {
     this._stroke = false;
     this._fill = false;
-    if (drawable._stroke) {
-      this.ctx.lineWidth = drawable._strokeWeight;
-      this.ctx.strokeStyle = drawable._stroke.toStr
-        ? drawable._stroke.toStr()
-        : drawable._stroke;
+    let stroke = getVal(drawable._stroke);
+    let fill = getVal(drawable._fill);
+    if (stroke) {
+      this.ctx.lineWidth = getVal(drawable._strokeWeight);
+      this.ctx.strokeStyle = stroke.toStr ? stroke.toStr() : stroke;
       this._stroke = true;
-    } else if (drawable._fill) {
-      this.ctx.fillStyle = drawable._fill.toStr
-        ? drawable._fill.toStr()
-        : drawable._fill;
+    } else if (fill) {
+      this.ctx.fillStyle = fill.toStr ? fill.toStr() : fill;
       this._fill = true;
     }
   }
 
   drawLine(from, to) {
+    from = getVal(from);
+    to = getVal(to);
     this.ctx.beginPath();
     this.ctx.moveTo(from.x, from.y);
     this.ctx.lineTo(to.x, to.y);
@@ -89,13 +99,23 @@ export class World {
   }
 
   drawArc(center, radius, fromAngle, toAngle) {
+    center = getVal(center);
     this.ctx.beginPath();
-    this.ctx.arc(center.x, center.y, radius, fromAngle, toAngle);
+    this.ctx.arc(
+      center.x,
+      center.y,
+      getVal(radius),
+      getVal(fromAngle),
+      getVal(toAngle),
+    );
     if (this._stroke) this.ctx.stroke();
     if (this._fill) this.ctx.fill();
   }
 
   drawRect(center, width, height) {
+    center = getVal(center);
+    width = getVal(width);
+    height = getVal(height);
     this.ctx.beginPath();
     this.ctx.rect(center.x - width / 2, center.y - height / 2, width, height);
     if (this._stroke) this.ctx.stroke();
@@ -103,6 +123,7 @@ export class World {
   }
 
   drawPolygon(center, points) {
+    center = getVal(center);
     this.ctx.beginPath();
     this.ctx.moveTo(center.x + points[0].x, center.y + points[0].y);
     for (let i = 1; i < points.length; i++) {
diff --git a/examples/dataclock.html b/examples/dataclock.html
new file mode 100644
index 0000000..ac0d20d
--- /dev/null
+++ b/examples/dataclock.html
@@ -0,0 +1,47 @@
+<html>
+  <head> </head>
+  <body>
+    <canvas id="mainCanvas" width="500" height="500"></canvas>
+    <script type="module">
+      import {
+        artworld,
+        Color,
+        Pico8,
+        Group,
+        Rect,
+        Random,
+        Vector2,
+        Line,
+        Circle,
+        Var,
+        degToRad,
+      } from "../artworld/index.js";
+      artworld.bindCanvas("mainCanvas");
+      window.artworld = artworld;
+
+      // declare some time-fluctuation variables
+      let color = new Var(
+        (t) =>
+          [Pico8.RED, Pico8.ORANGE, Pico8.GREEN, Pico8.BLUE][
+            Math.floor(t / 60) % 4
+          ],
+      );
+      let outerR = new Var((t) => Math.sin(t / 100) * 50 + 200);
+      // simple dependency
+      let innerR = new Var(() => outerR.getValue() - 10);
+      // example of a more complex Var that uses other vars
+      let lineTo = new Var((t) => {
+        let angle = (t / 6000) * Math.PI * 2;
+        return Vector2.polar(innerR.getValue(), angle);
+      });
+
+      let g = new Group().pos(new Vector2(250, 250));
+      new Circle(g).fill(Pico8.BLACK).z(1).radius(outerR);
+      new Circle(g).z(10).fill(color).radius(innerR);
+      new Circle(g).radius(20).fill(Pico8.BLACK).z(50);
+      new Line(g).to(lineTo).z(100);
+
+      artworld.loopStep();
+    </script>
+  </body>
+</html>