As常用的公式（留着）

基本三角函数的计算：

角的正弦值 = 对边 / 斜边

角的余弦值 = 邻边 / 斜边

角的正切值 = 对边 / 邻边

 

角度制与弧度制的相互转换：

弧度 = 角度 * Math.PI / 180

角度 = 弧度 * 180 / Math.PI

 

计算两点间距离：

dx = x2 – x1;

dy = y2 – y1;

 

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

 

maps.x = maps.x-(maps.x-mouseX)/5;  //////跟随鼠标

//==========================================================================================================

移除出界对象： 

if(sprite.x - sprite.width / 2 > right || sprite.x + sprite.width / 2 < left || sprite.y – sprite.height / 2 > bottom || sprite.y + sprite.height / 2 < top)

 { 

// 移除影片的代码 

}

//===========================================================

重置出界对象：

 if(sprite.x - sprite.width / 2 > right || sprite.x + sprite.width / 2 < left || sprite.y – sprite.height / 2 > bottom || sprite.y + sprite.height / 2 < top) 

{ 

// 重置影片的位置和速度 

}

//=======================================================

屏幕环绕出界对象：

 if (sprite.x - sprite.width / 2 > right) { sprite.x = left - sprite.width / 2; } else if (sprite.x + sprite.width / 2 < left) { sprite.x = right + sprite.width / 2; } if (sprite.y – sprite.height / 2 > bottom) 

{ 

sprite.y = top – sprite.height / 2; 

} 

else if (sprite.y + sprite.height / 2 < top) 

{ 

sprite.y = bottom + sprite.height / 2; 

}

//=============================================================

摩擦力应用（正确方法）：

 speed = Math.sqrt(vx * vx + vy * vy); 

 angle = Math.atan2(vy, vx); 

 if (speed > friction) 

{ 

speed -= friction;

 } 

else 

{ 

speed = 0; 

} 

vx = Math.cos(angle) * speed; 

vy = Math.sin(angle) * speed;

/////////////////////========================================

摩擦力应用（简便方法）： 

vx *= friction; vy *= friction;

//=====================================================

缓动公式:

sprite.x += (targetX - sprite.x) * easing;//easing为缓动系数变量

sprite.y += (targetY - sprite.y) * easing;

 

弹性公式:

vx += (targetX - sprite.x) * spring;//spring为弹性系数

vy += (targetY - sprite.y) * spring;

sprite.x += (vx *= friction);//friction为摩擦力

sprite.y += (vy *= friction);

 

//判断碰撞需要知道两个 ball 之间的角度，使用 Math.atan2(dy, dx)

 

var angle:Number = Math.atan2(dy, dx); var sin:Number = Math.sin(angle); var cos:Number = Math.cos(angle);

 

偏移弹性公式:

var dx:Number = sprite.x - fixedX;

var dy:Number = sprite.y - fixedY;

var angle:Number = Math.atan2(dy, dx);

var targetX:Number = fixedX + Math.cos(angle) * springLength;

var targetY:Number = fixedX + Math.sin(angle) * springLength;

 

 

 

多物体碰撞检测：

var numObjects:uint = 10;

for (var i:uint = 0; i < numObjects ‐ 1; i++) {

// 使用变量 i提取引用

var objectA = objects[i];

for (var j:uint = i+1; j<numObjects; j++) {

//使用变量 j 提取引用

var objectB = objects[j];

//在 objectA 与 objectB 之间进行碰撞检测

}

}

 

向鼠标旋转(或向某点旋转)

dx = mouseX - sprite.x;

dy = mouseY - sprite.y;

sprite.rotation = Math.atan2(dy, dx) * 180 / Math.PI;

 

 

坐标旋转：

 

 x1 = Math.cos(angle) * x - Math.sin(angle) * y; 

 y1 = Math.cos(angle) * y + Math.sin(angle) * x;

反坐标旋转：

 

 x1 = Math.cos(angle) * x + Math.sin(angle) * y; 

 y1 = Math.cos(angle) * y - Math.sin(angle) * x;

 

//=============================================================单轴上的动量守恒 距离碰撞检测：

           (m0 – m1) * v0 + 2 * m1 * v1

 v0Final=--------------------------------

              m0 + m1

//======================================================mass=质量  vx为速度

 

var vx0Final:Number = ((ball0.mass - ball1.mass) * ball0.vx + 2 * ball1.mass * ball1.vx) / (ball0.mass + ball1.mass);

 

 

//===================================================================================================优化后的代码

 

var vxTotal:Number = ball0.vx - ball1.vx;

ball0.vx = ((ball0.mass - ball1.mass) * ball0.vx + 2 * ball1.mass * ball1.vx) / (ball0.mass + ball1.mass);

ball1.vx = vxTotal + ball0.vx;

 

//=============================================

 

引力的一般公式：

 

 

force = G * m1 * m2 / distance2

 

 

ActionScript 实现万有引力:

 

 

function gravitate(partA:Ball, partB:Ball):void

{

var dx:Number = partB.x ‐ partA.x;

var dy:Number = partB.y ‐ partA.y;

var distSQ:Number = dx * dx + dy * dy;

var dist:Number = Math.sqrt(distSQ);

var force:Number = partA.mass * partB.mass / distSQ;

var ax:Number = force * dx / dist;

var ay:Number = force * dy / dist;

partA.vx += ax / partA.mass;

partA.vy += ay / partA.mass;

partB.vx ‐= ax / partB.mass;

partB.vy ‐= ay / partB.mass;

}

 

 

 

波形运动:

public function onEnterFrame1(event:Event):void {

ball.y=centerScale+Math.sin(angle)*range;

angle+=speed;

}

 

心跳:

public function onEnterFrame1(event:Event):void {

ball.scaleX=centerScale+Math.sin(angle)*range;

ball.scaleY=centerScale+Math.sin(angle)*range;

angle+=speed;

}

 

圆心旋转:

public function onEnterFrame(event:Event):void {

ball.x=centerX+Math.cos(angle)*radius;

ball.y=centerY+Math.sin(angle)*radius;

angle+=speed;

}

 

椭圆旋转:

public function onEnterFrame(event:Event):void {

ball.x=centerX+Math.cos(angle)*radiusX;

ball.y=centerY+Math.sin(angle)*radiusY;

angle+=speed;

}

 

颜色运算得到透明值:

var t:uint=0×77ff8877

var s:uint=0xff000000

var h:uint=t&s

var m:uint=h>>>24

trace(m)

 

转换为十进制:

trace(hexValue);

十进制转换为十六进制:

decimalValue.toString(16)

 

颜色提取:

red = color24 >> 16;

green = color24 >> 8 & 0xFF;

blue = color24 & 0xFF;

alpha = color32 >> 24;

red = color32 >> 16 & 0xFF;

green = color32 >> 8 & 0xFF;

blue = color232 & 0xFF;

 

按位计算得到颜色值:

color24 = red << 16 | green << 8 | blue;

color32 = alpha << 24 | red << 16 | green << 8 | blue;

 

过控制点的曲线:

// xt, yt是你想要让曲线通过的那一点

// x0, y0 和x2, y2 是曲线的终点

 

x1 = xt * 2 – (x0 + x2) / 2;

y1 = yt * 2 – (y0 + y2) / 2;

moveTo(x0, y0);

curveTo(x1, y1, x2, y2);