Flash basic Theory Class 19th Chapter Practical Skill Ⅲ

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Practical formula

In the book, we already have a variety of motion and effect formulas. I've extracted the most useful and commonly used formulas, equations, and snippets of code, and listed them at the end of this chapter. I think it would be very helpful to put them in the same place, so I put these things that I think most needed together as a reference for the whole. I will be on this page to write a letter.

Chapter III

Calculation of the underlying trigonometric function:

Sine value of angle = pair edge/Bevel

Cosine of angle = adjacent edge/hypotenuse

Tangent of angle = to edge/adjacent edge

Radians convert to angle and angle to radians:

radians = angle * math.pi/180

Angle = radians * 180/MATH.PI

Rotate to the mouse (or to any point):

// 用要旋转到的 x, y 坐标替换 mouseX, mouseY
dx = mouseX - sprite.x;
dy = mouseY - sprite.y;
sprite.rotation = Math.atan2(dy, dx) * 180 / Math.PI;

To create a waveform:

// 将x, y 或其它属性赋值给Sprite 影片或影片剪辑，
// 作为绘图坐标，等等。
public function onEnterFrame(event:Event){
　value = center + Math.sin(angle) * range;
　angle += speed;
}

To create a circle:

// 将x, y 或其它属性赋值给Sprite 影片或影片剪辑，
// 作为绘图坐标，等等。
public function onEnterFrame(event:Event){
　xposition = centerX + Math.cos(angle) * radius;
　yposition = centerY + Math.sin(angle) * radius;
　angle += speed;
}

To create an ellipse:

// 将x, y 或其它属性赋值给Sprite 影片或影片剪辑，
// 作为绘图坐标，等等。
public function onEnterFrame(event:Event){
　xposition = centerX + Math.cos(angle) * radiusX;
　yposition = centerY + Math.sin(angle) * radiusY;
　angle += speed;
}

Get the distance between two points:

// x1, y1 和 x2, y2 是两个点
// 也可以是 Sprite / MovieClip 坐标，鼠标坐标，等等。
dx = x2 – x1;
dy = y2 – y1;
dist = Math.sqrt(dx*dx + dy*dy);