Flash动画教程学习（三）高级运动

第三部分 高级运动

第八章 缓动和弹性

1. 缓动：越是靠近目标越慢

                            var vx:Number = (targetX - ball.x) * easing;

                            var vy:Number = (targetY - ball.y) * easing;

                            ball.x += vx;

                                ball.y += vy;

何时停止缓动？

If（Math.abs(dx)<1）{

  Ball.x = target;

  removeEventListener(Event.ENTER_FRAME);

  trace(“done”);

}

跟随目标移动：

                            var vx:Number = (mouseX - ball.x) * easing;

                            var vy:Number = (mouseY - ball.y) * easing;

                            ball.x += vx;

                                ball.y += vy;

1. 缓动不只是应用于运动：

透明度：ball.alpha += (targetAlpha-ball.alpha)*easing;

旋转：arrow.rotation += (targetRotation-arrow.rotation)*easing;

颜色：red += (redTarget - red)*easing;

1. 弹性：（一维弹性）越是靠近目标越快（初始位置和目标位置保持一定距离，以便加速）

                            var dx:Number = targetX - ball.x;

                            var ax:Number = dx * spring;

                            vx += ax;

                                ball.x += vx;

加入摩擦值：

                            var dx:Number = targetX - ball.x;

                            var ax:Number = dx * spring;

                            vx += ax;

                            vx *= friction;//0.95

                                ball.x += vx;

二维弹性：带摩擦力

                            var dx:Number = targetX - ball.x;

                            var dy:Number = targetY - ball.y;

                            var ax:Number = dx * spring;

                            var ay:Number = dy * spring;

                            vx += ax;

                            vy += ay;

                            vx *= friction;

                            vy *= friction;

                            ball.x += vx;

                                ball.y += vy;

移动目标点的弹性：跟随鼠标弹动（将targetX更改为mouseX就OK了）

                            var dx:Number = mouseX - ball.x;

                                var dy:Number = mouseY - ball.y;

画出求与鼠标间的线：

                            graphics.clear();

                            graphics.lineStyle(1);

                            graphics.moveTo(mouseX, mouseY);

                                graphics.lineTo(ball.x, ball.y);

多目标点弹性：

利用函数调用、循环、数组实现