<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Canvas Particle Constellation</title>
    <style>
        body {
            margin: 0;
            overflow: hidden; /* Hide scrollbars */
            background-color: #0d0d21; /* Dark navy background */
        }
        canvas {
            display: block; /* Remove default margin */
        }
    </style>
</head>
<body>
    <canvas id="constellationCanvas"></canvas>

    <script>
        const canvas = document.getElementById('constellationCanvas');
        const ctx = canvas.getContext('2d');

        // Set canvas to full screen
        canvas.width = window.innerWidth;
        canvas.height = window.innerHeight;

        // --- Configuration ---
        const config = {
            particleColor: `rgba(0, 191, 255, 0.7)`, // Deep sky blue with some transparency
            lineColor: `rgba(0, 191, 255, 0.3)`,
            particleAmount: 100,
            defaultSpeed: 0.5,
            defaultRadius: 3,
            linkRadius: 150, // Max distance to draw a line
        };

        // --- Mouse Interaction ---
        let mouse = {
            x: null,
            y: null,
            radius: config.linkRadius,
        };

        window.addEventListener('mousemove', (event) => {
            mouse.x = event.x;
            mouse.y = event.y;
        });
        window.addEventListener('mouseout', () => {
            mouse.x = null;
            mouse.y = null;
        });


        // --- Particle Class ---
        class Particle {
            constructor(x, y, radius, speed) {
                this.x = x;
                this.y = y;
                this.radius = radius;
                // Randomize velocity for movement in any direction
                this.vx = (Math.random() - 0.5) * speed;
                this.vy = (Math.random() - 0.5) * speed;
            }

            // Draw the particle on the canvas
            draw() {
                ctx.beginPath();
                ctx.arc(this.x, this.y, this.radius, 0, Math.PI * 2);
                ctx.fillStyle = config.particleColor;
                ctx.fill();
            }

            // Update particle position and handle bouncing off edges
            update() {
                // Bounce off horizontal walls
                if (this.x + this.radius > canvas.width || this.x - this.radius < 0) {
                    this.vx = -this.vx;
                }
                // Bounce off vertical walls
                if (this.y + this.radius > canvas.height || this.y - this.radius < 0) {
                    this.vy = -this.vy;
                }
                this.x += this.vx;
                this.y += this.vy;
            }
        }

        let particles = [ ];

        // --- Initialization ---
        function init() {
            particles = [ ];
            for (let i = 0; i < config.particleAmount; i++) {
                const x = Math.random() * canvas.width;
                const y = Math.random() * canvas.height;
                particles.push(new Particle(x, y, config.defaultRadius, config.defaultSpeed));
            }
        }

        // --- Line Drawing Logic ---
        function drawLines() {
            let allPoints = [...particles, mouse]; // Include mouse as a point to connect to

            for (let i = 0; i < allPoints.length; i++) {
                for (let j = i + 1; j < allPoints.length; j++) {
                    // Skip if the mouse point is not on the canvas
                    if (allPoints[i].x === null || allPoints[j].x === null) continue;

                    const dx = allPoints[i].x - allPoints[j].x;
                    const dy = allPoints[i].y - allPoints[j].y;
                    const distance = Math.sqrt(dx * dx + dy * dy);

                    if (distance < config.linkRadius) {
                        ctx.beginPath();
                        ctx.moveTo(allPoints[i].x, allPoints[i].y);
                        ctx.lineTo(allPoints[j].x, allPoints[j].y);
                        // Make lines more transparent the further they are
                        ctx.strokeStyle = `rgba(0, 191, 255, ${1 - distance / config.linkRadius})`;
                        ctx.lineWidth = 1;
                        ctx.stroke();
                        ctx.closePath();
                    }
                }
            }
        }

        // --- Animation Loop ---
        function animate() {
            // Clear the canvas
            ctx.clearRect(0, 0, canvas.width, canvas.height);

            // Update and draw each particle
            for (const particle of particles) {
                particle.update();
                particle.draw();
            }
            
            // Draw the connecting lines
            drawLines();

            // Request the next frame
            requestAnimationFrame(animate);
        }

        // --- Start ---
        init();
        animate();

        // --- Handle window resizing ---
        window.addEventListener('resize', () => {
            canvas.width = window.innerWidth;
            canvas.height = window.innerHeight;
            mouse.radius = config.linkRadius;
            init(); // Re-initialize particles for the new size
        });
    </script>
</body>
</html>