JavaScript中的三角函数应用公式

1、角度和弧度转换

radius = degrees * Math.PI / 180;
degrees = radius *180 / Math.PI

2、图形跟随鼠标转动

dx = mouse.x - obj.x;
dy = mouse.y - obj.y;
obj.rotation = Math.atan2(dy,dx)*180 / Math.PI

3、创建波动

                (function drawFrame() {

                    window.requestAnimationFrame(drawFrame, canvas);
                    context.clearRect(0, 0, canvas.width, canvas.height);
                    ball.x += xspeed;
                    ball.y = centerY / 2 + Math.sin(angle) * range;

                    ball.draw(context)
                }())

4、创建圆形

                 (function drawFrame() {
                     window.requestAnimationFrame(drawFrame, canvas);
                     context.clearRect(0, 0, canvas.width, canvas.height);

                     ball.x = centerX + Math.sin(angle) * radius;
                     ball.y = centerY + Math.cos(angle) * radius;
                     angle += speed;

                     ball.draw(context)
                 }())

5、创建椭圆

                (function drawFrame() {
                    window.requestAnimationFrame(drawFrame, canvas);
                    context.clearRect(0, 0, canvas.width, canvas.height);

                    ball.x = centerX + Math.sin(angle) * radiusX;
                    ball.y = centerY + Math.cos(angle) * radiusY
                    angle += speed
                    ball.draw(context)
                }())

6、两点之间的距离：

dx = x1  -  x2;
dy = y1  -  y2;

dist = Math.sqrt(dx*dx + dy*dy);

正在更新中...