add splines

2024-09-27 14:41:24 +02:00 · 2024-09-27 14:41:24 +02:00 · af199a6d9c
commit af199a6d9c
parent a200c3d3cf
2 changed files with 82 additions and 0 deletions
--- a/spline.html
+++ b/spline.html
@ -0,0 +1,12 @@
+<!DOCTYPE HTML>
+<html lang="en">
+<head>
+    <meta charset="UTF-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1.0">
+    <title>Document</title>
+</head>
+<body style="margin: 0; padding 0; overflow: hidden; background-color: #000000">
+    <canvas id="canvas" width="800" height="600"></canvas>
+</body>
+<script type="module" src="spline.js"></script>
+</html>
--- a/spline.js
+++ b/spline.js
@ -0,0 +1,70 @@
+import { resizeCanvas, drawCircle, drawLine, cubicBezier } from "./common.js"
+
+function drawPoints(ctx, points) {
+    for (const p of points) {
+        drawCircle(ctx, p, 2, 0xFF00FF);
+    }
+}
+
+
+function drawCurve(ctx, curve) {
+    for (let i=0; i < curve.length - 1; ++i) {
+        drawLine(ctx, curve[i], curve[i+1], 0xFFFFFF);
+    }
+}
+
+function draw(ctx, points) {
+    const bezier1 = cubicBezier(...points.slice(0, 4));
+    drawCurve(ctx, bezier1);
+
+    const bezier2 = cubicBezier(...points.slice(3, 7));
+    drawCurve(ctx, bezier2);
+
+    drawPoints(ctx, points);
+}
+
+function init() {
+    const canvas = document.getElementById("canvas");
+    let selection = undefined;
+    let points = [
+        { x: 227, y: 434 },
+        { x: 341, y: 234 },
+        { x: 649, y: 255 },
+        { x: 765, y: 450 },
+        { x: 800, y: 500 },
+        { x: 850, y: 450 },
+        { x: 900, y: 550 },
+    ];
+    
+    if (canvas.getContext) {
+        const ctx = canvas.getContext("2d");
+        resizeCanvas(ctx); // Init canvas
+        draw(ctx, points);
+
+        canvas.onmousedown = (evt) => {
+            const { clientX, clientY } = evt;
+            for (const p of points) {
+                if (Math.abs(p.x - clientX) < 10 && Math.abs(p.y - clientY) < 10) {
+                    selection = points.indexOf(p);
+                }
+            }
+        };
+
+        canvas.onmousemove = (evt) => {
+            if (selection !== undefined) {
+                points[selection].x = evt.clientX;
+                points[selection].y = evt.clientY;
+                // redraw
+                ctx.clearRect(0, 0, ctx.canvas.width, ctx.canvas.height);
+                draw(ctx, points);
+            }
+        };
+
+        canvas.onmouseup = () => {
+            selection = undefined;
+        };
+
+    }
+}
+
+init();