 <!DOCTYPE html>
<html>
<head>
    <title>Bouncing Ball in Rotating Square</title>
    <style>
        canvas {
            border: 1px solid #000;
        }
    </style>
</head>
<body>
    <script>
        const canvas = document.createElement('canvas');
        const ctx = canvas.getContext('2d');
        canvas.width = 800;
        canvas.height = 600;
        document.body.appendChild(canvas);

        // Simulation parameters
        let angle = 0;
        const rotationSpeed = 0.01; // Radians per frame
        const squareSize = 400;     // Square side length
        const halfSize = squareSize / 2;
        const centerX = canvas.width / 2;
        const centerY = canvas.height / 2;
        const ballRadius = 10;

        // Ball state
        let posX = centerX;
        let posY = centerY;
        let velX = 3;
        let velY = 3;

        function updatePhysics() {
            // Update ball position
            posX += velX;
            posY += velY;

            // Convert to square's local coordinate system
            const translatedX = posX - centerX;
            const translatedY = posY - centerY;
            const cosAngle = Math.cos(angle);
            const sinAngle = Math.sin(angle);
            
            let localX = translatedX * cosAngle + translatedY * sinAngle;
            let localY = -translatedX * sinAngle + translatedY * cosAngle;

            // Check collisions and adjust position
            let collisionX = false, collisionY = false;
            
            // X-axis collisions
            if (localX < -halfSize + ballRadius) {
                localX = -halfSize + ballRadius;
                collisionX = true;
            } else if (localX > halfSize - ballRadius) {
                localX = halfSize - ballRadius;
                collisionX = true;
            }

            // Y-axis collisions
            if (localY < -halfSize + ballRadius) {
                localY = -halfSize + ballRadius;
                collisionY = true;
            } else if (localY > halfSize - ballRadius) {
                localY = halfSize - ballRadius;
                collisionY = true;
            }

            // If collision occurred, update position and velocity
            if (collisionX || collisionY) {
                // Convert back to global coordinates
                const newTX = localX * cosAngle - localY * sinAngle;
                const newTY = localX * sinAngle + localY * cosAngle;
                posX = newTX + centerX;
                posY = newTY + centerY;

                // Update velocity in local space
                let localVelX = velX * cosAngle + velY * sinAngle;
                let localVelY = -velX * sinAngle + velY * cosAngle;

                if (collisionX) localVelX *= -1;
                if (collisionY) localVelY *= -1;

                // Convert velocity back to global space
                velX = localVelX * cosAngle - localVelY * sinAngle;
                velY = localVelX * sinAngle + localVelY * cosAngle;
            }
        }

        function draw() {
            ctx.clearRect(0, 0, canvas.width, canvas.height);
            
            // Draw rotating square
            ctx.save();
            ctx.translate(centerX, centerY);
            ctx.rotate(angle);
            ctx.strokeStyle = 'black';
            ctx.lineWidth = 2;
            ctx.strokeRect(-halfSize, -halfSize, squareSize, squareSize);
            ctx.restore();

            // Draw ball
            ctx.beginPath();
            ctx.arc(posX, posY, ballRadius, 0, Math.PI * 2);
            ctx.fillStyle = 'yellow';
            ctx.fill();
            ctx.strokeStyle = 'black';
            ctx.stroke();
        }

        function animate() {
            angle += rotationSpeed;
            updatePhysics();
            draw();
            requestAnimationFrame(animate);
        }

        // Start animation
        animate();
    </script>
</body>
</html>

created 3 months ago

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