CODEWITHSUNDEEP
flashactionscript-3
John
John

Reputation: 131

actionscript 3 rotation

Here is my question:

I have a movieclip called player and i want to get his rotation;

player.rotation=0;
player.rotation-=90;
trace(player.rotation);//this traces -90, not 270

I would like to know why it dosent say the rotation is 270, because 0 is like 360 and when you rotate 90 degres left it should be 270;

I am asking this because it causes a problem in my game

Thanks

Upvotes: 0

Views: 6156

Answers (2)

Chunky Chunk
Chunky Chunk

Reputation: 17217

-90 and 270 are different values, but a sprite with these values assigned to its rotation property will appear the same because rotation values for Display Objects do not have a limited range. from the documentation flash.display.DisplayObject.rotation:

Values from 0 to 180 represent clockwise rotation; values from 0 to -180 represent counterclockwise rotation. Values outside this range are added to or subtracted from 360 to obtain a value within the range. For example, the statement my_video.rotation = 450 is the same as my_video.rotation = 90.

if you want to limit this range you will have to create your own function to do so.

Upvotes: 3

Marty
Marty

Reputation: 39456

Rotation in Flash begins from the east and then increments up to 180 clockwise or decrements counter-clockwise down to -179.

enter image description here

For game development I recommend sticking to radians for any angular mathematics you need to do and using rotation for display/rendering only.

Here is a small demo that outputs the rotation from 0 to 360 (0):

var shape:Shape = new Shape();

for(var i:int = 0; i<360; i++)
{
    shape.rotation ++;
    trace(shape.rotation);
}

You'll notice that the output clocks over to -179 after 180.

Upvotes: 1

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