summaryrefslogtreecommitdiff
path: root/src/assets/trading-in-the-rain/RainCanvas.js
diff options
context:
space:
mode:
Diffstat (limited to 'src/assets/trading-in-the-rain/RainCanvas.js')
-rw-r--r--src/assets/trading-in-the-rain/RainCanvas.js74
1 files changed, 74 insertions, 0 deletions
diff --git a/src/assets/trading-in-the-rain/RainCanvas.js b/src/assets/trading-in-the-rain/RainCanvas.js
new file mode 100644
index 0000000..5396eb5
--- /dev/null
+++ b/src/assets/trading-in-the-rain/RainCanvas.js
@@ -0,0 +1,74 @@
+function RainCanvas(canvasDOM) {
+ this.canvas = canvasDOM;
+ this.ctx = this.canvas.getContext("2d");
+
+ this.drops = [];
+ this.tick = 0;
+
+ // drop: {x, y, intensity, color} (all in range [0, 1], except color which is
+ // an array [r,g,b])
+ this.newDrop = (newDrop) => {
+ if (!document.hasFocus()) return;
+
+ // scale intensity up a bit right off the bat. If the intensity was near 0
+ // the drop wouldn't actually show up at all.
+ newDrop.intensity = distribute(newDrop.intensity, 0, 1, 0.1, 1);
+ newDrop.tick = this.tick;
+ this.drops.push(newDrop);
+ };
+
+ // alpha isn't really alpha, it's used to determine line width, but it plays
+ // the same role.
+ this.drawDrop = (drop, alpha) => {
+ let cW = this.canvas.width, cH = this.canvas.height;
+ let minDim = Math.min(cW, cH);
+
+ let tickDiff = this.tick - drop.tick;
+ let radius = tickDiff * (minDim / 250);
+ let x = distribute(drop.x, 0, 1, cW*0.1, cW*0.9);
+ let y = distribute(drop.y, 0, 1, cH*0.1, cH*0.9);
+
+ this.ctx.beginPath();
+ this.ctx.arc(x, y, radius, 0, Math.PI * 2, false);
+ this.ctx.closePath();
+
+ // multiple lineWidth by alpha so that the line width drops over time in
+ // correspondence with the opacity.
+ this.ctx.lineWidth = distribute(drop.intensity, 0, 1, 2, 9) * alpha;
+
+ let r = drop.color[0], g = drop.color[1], b = drop.color[2];
+ this.ctx.strokeStyle = `rgba(${r}, ${g}, ${b}, 1)`;
+ this.ctx.stroke();
+ };
+
+ let requestAnimationFrame =
+ window.requestAnimationFrame ||
+ window.mozRequestAnimationFrame ||
+ window.webkitRequestAnimationFrame ||
+ window.msRequestAnimationFrame;
+
+ this.doTick = () => {
+ this.canvas.width = window.innerWidth;
+ this.canvas.height = window.innerHeight;
+ this.ctx.clearRect(0, 0, this.canvas.width, this.canvas.height);
+
+ let newDrops = [];
+ for (let i in this.drops) {
+ let drop = this.drops[i];
+ let alpha = distribute(
+ this.tick - drop.tick,
+ 0, 200 * drop.intensity,
+ 1, 0,
+ );
+ if (alpha <= 0) continue;
+
+ this.drawDrop(drop, alpha);
+ newDrops.push(drop);
+ }
+ this.drops = newDrops;
+
+ this.tick++;
+ requestAnimationFrame(this.doTick);
+ };
+ requestAnimationFrame(this.doTick);
+}