I need to move many objects in a curve path across screen randomly. The objects start path and towards path also should take randomly. I had searched on google and finally i found one usefull tutorial to draw a curve. But i don't know how to move the objects using that curve path. But i am sure there would be some formula in as3 which has to use sin and cos theta. So please let me know if anybody have a solution for my problem. And also if i got any sample projects also would be very usefull for me.
And the link which i got to draw curve is as follows.
http://active.tutsplus.com/tutorials/actionscript/the-math-and-actionscript-of-curves-drawing-quadratic-and-cubic-curves/?search_index=4.
Thanks in advance.Immediate Help would be appreciated.
A quick'n'dirty would be using polar to cartesian coordinates(sin and cos) as you mentioned:
import flash.events.Event;
var a:Number = 0;//angle
var ra:Number = .01;//random angle increment
var rx:Number = 100;//random trajectory width
var ry:Number = 100;//random trajectory height
graphics.lineStyle(1);
addEventListener(Event.ENTER_FRAME,function (event:Event):void{
a += ra;//increment angle
rx += a;//fidle with radii otherwise it's gonna be a circle
ry += a;//feel free to play with these
graphics.lineTo(225 + (Math.cos(a) * rx),//offset(225,200)
200 + (Math.sin(a) * ry));//and use pol to car conversion
if(a > Math.PI) reset();//reset at 180 or any angle you like
});
function reset():void{
trace('reset');//more values to tweak here
a = Math.random();
ra = Math.random() * .0001;
rx = 20 + Math.random() * 200;
ry = 20 + Math.random() * 200;
}
Random numbers need tweaking to get mostly rounder ellipses (rather than flatter ones), but the principle is the same.
If you don't mind using libraries, why not try TweenLite's BezierPlugin or BezierThroughPlugin. Should be easy to randomize start/end points.
Also you can check out the first part of this older answer on quadratic,cubic and hermite interpolation
In my example I'm drawing a path, but of course, you could use those computed x,y coordinates to plug into a DisplayObject to move it on screen.
Related
Using some code I found online has helped me create a zoom function for a program I am attempting to make. It is to make a map that allows a user to mark points. Currently the code scales in on the map image alone but I cant get the point icons to realign to where they originally where. I cant workout the maths of it.
Code to zoom in and out
if (mev.shiftKey) {
image.scaleX = Math.max(scaleFactor*image.scaleX, minScale);
image.scaleY = Math.max(scaleFactor*image.scaleY, minScale);
}
if (mev.ctrlKey) {
image.scaleX = Math.min(1/scaleFactor*image.scaleX, maxScale);
image.scaleY = Math.min(1/scaleFactor*image.scaleY, maxScale);
mat = image.transform.matrix.clone();
MatrixTransformer.matchInternalPointWithExternal(mat,internalCenter,externalCenter);
image.transform.matrix=mat;
This allows the image to scale up with the following factors
public var scaleFactor:Number = 0.8;
public var minScale:Number = 0.25;
public var maxScale:Number = 2.0;
The problem occurs when I try to move the pointer icons that are overlaid on this image. They are not to grow or shrink at the moment but they I cant get the maths to get them to move the correct number of pixels away from the mouse location so that they are still in line. Currently I am using the following formulas
//decrease zoom
stage.getChildAt(i).x = stage.getChildAt(i).x * scaleFactor;
//increase zoom
stage.getChildAt(i2).x = stage.getChildAt(i2).x / scaleFactor;
Any thoughts ? Code I am using came from
http://www.flashandmath.com/howtos/zoom/
Quite a few elements missing from the question like the moving map underneath. Anyway now that it's sorted out ...
If you are not a math genius and can't tackle 2 math formulas at the same time then don't and tackle them one by one then combine them. Once again don't use the x,y property of point for calculation but create specific property (like in a custom class for example). I will name them here origin for convenience.
Given a point with origin property of x:100, y:200, its position on the map is (assuming map is top left coordinate, if not adapt accordingly):
point.x = map.x + point.origin.x;
point.y = map.y + point.origin.y;
the positioning is solved now you need to solve for scale which is easy:
point.x = point.origin.x * scaleFactor;
point.y = point.origin.y * scaleFactor;
Both systems are solved now you can combine the two:
point.x = map.x + (point.origin.x * scaleFactor);
point.y = map.y + (point.origin.y * scaleFactor);
i have a little math/coding problem witch i don`t have any idea how could i do it work in a simple way, so the problem is is need to make a line shorter, with 15
in my program i have :
http://gyazo.com/aff5ff61fb9ad3ecedde3118d9c0895e
the line takes the center coordinates of both circles and draws from one to another, but i need it to be from the circumference of the circles, so it wont get inside
the code im using is :
var line:Shape = new Shape();
line.graphics.lineStyle(3,0xFF0000,2);
line.graphics.moveTo(sx,sy);
line.graphics.lineTo(fx,fy);
this.addChild(line);
arrow2(sx,sy,fx,fy);
var rline:Shape = new Shape();
rline.graphics.lineStyle(3,0xFF0000,2);
rline.graphics.moveTo(fx,fy);
rline.graphics.lineTo(xa,ya);
this.addChild(rline);
var rline2:Shape = new Shape();
rline2.graphics.lineStyle(3,0xFF0000,2);
rline2.graphics.moveTo(fx,fy);
rline2.graphics.lineTo(xb,yb);
this.addChild(rline2);
the rline and rline2 function is for the arrow lines, now my question is how do i make it shorter not depending on it direction so it will not overlap the circle
You can use vectors to solve your problem; they're pretty easy to get the hang of, and pretty much indispensable for things like game dev or what you're trying to do. You can get an overview here: http://www.mathsisfun.com/algebra/vectors.html or by searching "vector math" in google
So first step is to get a vector from one circle to another (pretty much what you've done):
var vector:Point = new Point( circle2.x - circle1.x, circle2.y - circle1.y );
var length:Number = vector.length; // store the length of the vector for later
This is the equivalent of saying "if you start at circle1 and move along vector, you'll arrive at circle2"
Next thing we're going to do is normalise it; all this does is set the length to 1 - the direction is unchanged - this makes it easier to work with for what you're looking to do. A vector with length 1.0 is called a unit vector:
vector.normalize( 1.0 ); // you can pass any length you like, but for this example, we'll stick with 1.0
Now, to draw a line from one circle to another, but starting from the outside, we simply find the start and the end points. The starting point is simple the position of circle1 plus vector (normalised to unit length) multiplied by the radius of circle1:
var sx:Number = circle1.x + vector.x * circle1.radius; // or circle1.width * 0.5 if you don't store the radius
var sy:Number = circle1.y + vector.y * circle1.radius;
The ending point can be found by starting at our start point, and continuing along our vector for a distance equal to the distance between the two circles (minus their radii). The length value that we created earlier is the distance between your two circles, from one center point to another, so we can use that to get the distance minus the radii:
var dist:Number = length - ( circle1.radius + circle2.radius ); // or circle1.width * 0.5 etc
And so the end point:
var ex:Number = sx + vector.x * dist;
var ey:Number = sy + vector.y * dist;
And to draw the line between them:
var line:Shape = new Shape;
line.graphics.lineStyle( 1.0, 0x000000 );
line.graphics.moveTo( sx, sy );
line.graphics.lineTo( ex, ey );
this.addChild( line )
I'm trying to zoom a DisplayObject into a certain point. I figured it would be easy, but I've spent a day now trying to figure it out.
Basically, I think this should work. Emphasis on should.
//newPoint is the point being centered. There is no initial scaling, so I do not need to compensate for that (yet)
//scale is the zoom level
//container is the parent of the obj
//obj is the object being scaled/panned
var p:Point = new Point(
( this.container.width - this.obj.width * scale + newPoint.x * scale ) / 2,
( this.container.height - this.obj.height * scale + newPoint.y * scale ) / 2
);
this.obj.scaleX = this.obj.scaleY = scale;
this.obj.x = p.x;
this.obj.y = p.y;
It centers the point if scale is 1, but it gets further and further away from center as you increase the scale. I've tried dozens of different methods. This method, which I have seen on several sites, produced the same exact results. Anyone have any idea how to get this to work?
EDIT 10-1-12:
As a followup, I took the code snippet that LondonDrugs_MediaServices provided as a basis for my original issue. I needed to be able to zoom to a specific point at a specific scale relative to the unscaled image (think how Google Maps zooms to a specific location). To do this, I had to center my image on the point before running the translation code. I've posted the additional code below. For other uses (pinch to zoom, scrolling, and double click), I used the code provided by Vesper, which worked quite well.
//obj is the object being translated
//container is its parent
//x and y are the coordinates to be zoomed to, in untranslated scaling
//obj.scaleX and obj.scaleY are always identical in my class, so there is no need to account for that
//calculates current center point, with scaling
var center:Point = new Point( ( this.container.width - this.obj.width * this.obj.scaleX ) / 2, ( this.container.height - this.obj.height * this.obj.scaleX ) / 2 );
//calulcates the distance from center the point is, with scaling
var distanceFromCenter:Point = new Point( this.obj.width * this.obj.scaleX / 2 - x * this.obj.scaleX, this.obj.height * this.obj.scaleX / 2 - y * this.obj.scaleX );
//center the object on that specific point
this.obj.x = center.x + distanceFromCenter.x;
this.obj.y = center.y + distanceFromCenter.y;
var mat:Matrix=new Matrix();
mat.translate(-p.x,-p.y);
mat.scale(desiredScale,desiredScale);
mat.translate(p.x,p.y);
yourObject.transform.matrix=mat;
The core point is that scaling is done around (0,0), but you can do it with matrix that describes affine transformations. You first make an empty matrix (that is, a matrix that doesn't transform), then apply a set of transformations to it. First, place a desired point at (0,0) by translating by -1*coordinates, then scale, then translate back.
hie guys....
thank's your comments...
i found the answer...
code :
gambar.addEventListener(TransformGestureEvent.GESTURE_ZOOM , onZoom);
function onZoom(event:TransformGestureEvent):void {
var locX:Number=event.localX;
var locY:Number=event.localY;
var stX:Number=event.stageX;
var stY:Number=event.stageY;
var prevScaleX:Number=gambar.scaleX;
var prevScaleY:Number=gambar.scaleY;
var mat:Matrix;
var externalPoint=new Point(stX,stY);
var internalPoint=new Point(locX,locY);
gambar.scaleX *= event.scaleX;
gambar.scaleY *= event.scaleY;
if(event.scaleX>1 && gambar.scaleX>6){
gambar.scaleX=prevScaleX;
gambar.scaleY=prevScaleY;
}
if(event.scaleY>1 && gambar.scaleY>6){
gambar.scaleX=prevScaleX;
gambar.scaleY=prevScaleY;
}
if(event.scaleX<1 && gambar.scaleX<0.8){
gambar.scaleX=prevScaleX;
gambar.scaleY=prevScaleY;
}
if(event.scaleY<1 && gambar.scaleY<0.8){
gambar.scaleX=prevScaleX;
gambar.scaleY=prevScaleY;
}
mat=gambar.transform.matrix.clone();
MatrixTransformer.matchInternalPointWithExternal(mat,internalPoint,externalPoint);
gambar.transform.matrix=mat;
}
The matrix answer is absolutely correct, but if you happen to be a Club GreenSock member you can get some nice functionality with very simple code with the TransformAroundPointPlugin
http://www.greensock.com/as/docs/tween/com/greensock/plugins/TransformAroundPointPlugin.html
You can see an example in the plugin explorer here:
http://www.greensock.com/tweenlite/#plugins
I use this to tween all my zooms and have much better performance than when I tried to do this manually. IMO the whole library is worth it's weight in gold (and no I have no connection other than liking the library). If you need any of the other features I'd look into it. It also has the ThrowProps plugin ( http://www.greensock.com/throwprops/ )which is very important if you are going to have a bounding box on mobile that you want to have a smooth return into the boundaries.
Set obj.x to -p.x and obj.y to -p.y, set the container scaleX and scaleY to the desired value and add p.x to the container x and p.y to the container y. Done!
First of all sorry for some english mistakes. Portuguese is my first language(I am from Brazil)
Im trying to make a space game from scratch in AS3 and the way to move the ship is like in the game Air Traffic Chief.
I succeed at some point. But when the ship is very fast it start to shake and its not very smooth and clean as I want.
Here is what i have done: http://megaswf.com/s/2437744
As the code is very big so I pasted in pastebin: pastebin.com/1YVZ23WX
I also wrote some english documentation.
This is my first game and my first post here. I really hope you guys can help me.
Thanks in advance.
Edit:
As the code is very big i will try to clarify here.
When the user MouseDown and MouseMove the ship every coordinate is passed to an array.
When the user MouseUP this array is passed to a function that fix the array.
For example: If the distance between two coordinates is greater than 5px, the function creates a coordinate in the middle of the two coordinates.
if I take this function off the problem seen to be solved. But if the user move the mouse very slow it still happens. It also creates a problem that i was trying to solve with that function. as the distance of the two coordinates are very big when the ship arrive in one coordinate most of the line path disappear.
I uploaded a version without the function that fixes the array. http://megaswf.com/s/2437775
I think there is 2 ways for solving this problem
1- Try to fix the noise in the array of coordinates 2- Take off the function that create an coordinate between two points and try to fix the problem of the line path disappear.
Here is the 2 important functions:
this function moves the ship
private function mover():void
{
if (caminhoCoords[0]!=null) // caminhoCoords is the array that contain the path
{
var angulo:Number = Math.atan2(this.y - caminhoCoords[0][1], this.x - caminhoCoords[0][0]);
this.rotation = angulo / (Math.PI / 180);
this.x = this.x - velocidade * (Math.cos(angulo));
this.y = this.y - velocidade * (Math.sin(angulo));
var testex:Number = Math.abs(this.x - caminhoCoords[0][0]); //test to see the distance between the ship and the position in the array
var testey:Number = Math.abs(this.y - caminhoCoords[0][1]);
if (testey<=velocidade+2 && testex<=velocidade+2) // if is velocidade+2 close then go to the next coordnate
{
caminhoCoords.shift();
}
}
}
This function draw the line:
private function desenhaCaminho():void //draw the black Path
{
if(caminhoCoords.length>=1)
{
caminho.graphics.clear();
caminho.graphics.lineStyle(1, 0x000000, 1,true);
caminho.graphics.moveTo(caminhoCoords[0][0],caminhoCoords[0][1]);
for (var i:int = 1; i < caminhoCoords.length; i++)
{
caminho.graphics.lineTo(caminhoCoords[i][0], caminhoCoords[i][1]);
}
}else
{
caminho.graphics.clear();
}
}
Every time the ship arrive in one coordinate is take that coordinate off the array and redraw the array.
Is there a better way of doing that?
I believe if you set your registration point of the plane to the centre and use .snapto(path), it will improve the action.
Judging from just the look of the stuttering, I would guess you need to smooth out the "line" a fair bit. It's probably picking up a lot of noise in the line, which is then translated into the rotation of the plane. Either smooth out the rotation/position of the plane, or the line itself.
I'm trying to find a function lng = f(lat) that would help me draw a line between 2 given GPS coordinates, (lat1, lng1) and (lat2, lng2).
I've tried the traditional Cartesian formula y=mx+b where m=(y2-y1)/(x2-x1), but GPS coordinates don't seem to behave that way.
What would be a formula/algorithm that could help me achieve my goal.
PS: I'm using Google Maps API but let's keep this implementation agnostic if possible.
UPDATE: My implementation was wrong and it seems the algorithm is actually working as stated by some of the answers. My bad :(
What you want to do should actually work. Keep in mind however that if north is on top, the horizontal (x) axis is the LONGITUDE and the vertical (y) axis is the LATITUDE (I think you might have confused this).
If you parametrize the line as lat = func(long) you will run into trouble with vertical lines (i.e. those going exactly north south) as the latitude varies while the longitude is fixed.
Therefore I'd rather use another parametrization:
long(alpha) = long_1 + alpha * (long_2 - long_1)
lat(alpha) = lat_1 + alpha * (lat_2 - lat_1)
and vary alpha from 0 to 1.
This will not exactly coincide with a great circle (shortest path on a sphere) but the smaller the region you are looking at, the less noticeable the difference will be (as others posters here pointed out).
Here is a distance formula I use that may help. This is using javascript.
function Distance(lat1, lat2, lon1, lon2) {
var R = 6371; // km
var dLat = toRad(lat2 - lat1);
var dLon = toRad(lon2 - lon1);
var a = Math.sin(dLat / 2) * Math.sin(dLat / 2) + Math.cos(toRad(lat1)) * Math.cos(toRad(lat2)) * Math.sin(dLon / 2) * Math.sin(dLon / 2);
var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
var d = R * c * 0.621371;
var r = Math.round(d * 100) / 100;
return r;
}
For short distances, where the earth curvature doesn't make a significant difference, it works fine to draw a line using regular two-dimensional geometry.
For longer distances the shortest way between two lines does not project as a straight line on a map, but as a curve. (For example, the shortest way from Sweden to Alaska would be straight over the noth pole, not past Canada and Iceland.) You would have to use three-dimensional geometry to draw a line on a surface of a sphere, then project that onto the map in the same way the earth surface is projected on the map.
Is your goal to find this equation or to actually draw a line?
If the latter, since you're using the Maps API, specify geodesic: true and draw it with a Polyline:
http://code.google.com/apis/maps/documentation/javascript/reference.html#Polyline