AS3 - Using Matrix3D objects for reordering display - actionscript-3

I'm working with about 20 objects that are moving around in 3D space. Adobe recommends "Using Matrix3D objects for reordering display":
Use the getRelativeMatrix3D() method of the Transform object to get the relative z-axes of the child 3D display objects.
Use the removeChild() method to remove the objects from the display list.
Sort the display objects based on their relative z-axis values.
Use the addChild() method to add the children back to the display list in reverse order.
Great. That's fine if the objects aren't moving. But what if there are animations happening and one object comes in front of another in z-space? The objects are displayed accoring to the position in the display list, not according to their z-order. How can you make objects respect z-order while animating (make object A appear in front of object B if object A's z-value becomes smaller than object B)? Obviously you can't clear the display list during an animation.

It's practically the same as adobe's docs says... and it works perfectly for moving objects.
The simplest way, so you have some code reference, and given you have all of your 3d objects in an array, would go something like this:
function zSort(objects:Array) {
objects.sortOn("z", Array.DESCENDING | Array.NUMERIC); // sort the array on the "z" property
for each(var clip:DisplayObject in objects) { //loop the array and add the childs in the corrected order...
addChild(clip);
}
}

Related

Check if a child exists

I have two Scenes. In scene 1, there is a script which automatically adds a child using addChild(nameObject);, there is also a button go to the next scene.
When I come back from scene 2 to scene 1, the code generates another object. How do I make an AS3 script that checks if the child does already exist on the stage?
You're most probably looking for the contains() method of a DisplayObjectContainer:
Determines whether the specified display object is a child of the
DisplayObjectContainer instance or the instance itself. The search
includes the entire display list including this DisplayObjectContainer
instance. Grandchildren, great-grandchildren, and so on each return
true.
if ( !contains(nameObject) ) {
// the object is not a child of the container
addChild(nameObject);
}

How do I get the global point of a rotated object?

I'm trying to get the global point (x,y) of an object. This object is a child of a rotated parent, MovieClip. Without rotation of the parent, it's easy to find the global point of the child, parent.localToGlobal. However, when I'm rotating the parent, it seems that localToGlobal returns the incorrect x,y.
localToGlobal deals with position not transformation. You are simply using the wrong tool for the job. I'm guessing you don't want to deal with matrices but you gonna have to.
mydisplayobject.transform.pixelBounds;//global space occupied by object
mydisplayobject.transform.concatenatedMatrix//the matrix representing all combined transofrmations

Actionscript 3: translating coordinates from object's 3D space to another's?

I feel like this has probably been asked/answered here, and if so, I apologize for the bandwidth, but I don't see any explanation.
How does one translate from one object's coordinate space to another in Flash AS3? I can take a point in an object and translate it to global coordinates using local3DToGlobal() and then to another object's local using globalToLocal3D() -- but is there a direct way?
Thus, if I wanted one object to be able to say to another: 'move your top left corner to my top left corner', even through the two objects are in different z-spaces, rotated 3-dimensionally, etc.
I assume it is in the matrix3D matrix manipulations —
Matrix multiplication? TransformVector()? deltaTransformVector()?
I have been poring over the API but would really appreciate a concrete example.
Thanks!
One approach would be getRelativeMatrix3D(), called from the transform property of a display object, as in: transform.getRelativeMatrix3d(root).position.
Returns a Matrix3D object, which can transform the space of a
specified display object in relation to the current display object's
space. You can use the getRelativeMatrix3D() method to move one
three-dimensional display object relative to another three-dimensional
display object.
From Adobe's Performing complex 3D transformations, there is an example using Matrix3D objects for reordering display, in which faces of a box are reordered to ensure that layering of 3D display objects corresponds to the relative depths after rotations have been applied:
var faces:Array;
for (var i:uint = 0; i < 6; i++)
{
faces[i].z = faces[i].child.transform.getRelativeMatrix3D(root).position.z;
this.removeChild(faces[i].child);
}
faces.sortOn("z", Array.NUMERIC | Array.DESCENDING);
for (i = 0; i < 6; i++)
{
this.addChild(faces[i].child);
}

Children of Children of MovieClip not showing up when MovieClip is added to stage?

This problem seems very simple to me, but I've been unable to fix it, or find an answer anywhere.
This is in a class constructor for a class called block, block_maker is the object that called the constructor, an instance of level.
this.bitmap = new Bitmap(this.bitmap_data);
this.addChild(this.bitmap);
this.block_maker.stage_foreground.addChild(this);
In level, stage_foreground is added to the stage, but nothing appears. trace(stage_foreground.numChildren); shows the correct count of children, and var temp = (this.stage_foreground.getChildAt(0)); trace(temp.numChildren); correctly but the children OF the children don't actually show up, the stage just stays blank.
When I change the above code to
this.bitmap = new Bitmap(this.bitmap_data);
this.block_maker.stage_foreground.addChild(this.bitmap);
the blocks appear on the stage, as children of level_instance.stage_foreground, but with this method, the bitmaps aren't appropriately positioned, as they have no position data. I can simply give this.bitmap x and y positions, and it works, but I am curious as to why it won't work when just adding the bitmap as a child to the block and then adding that as a child to stage_foreground.
I've tried replacing this.bitmap with a number of other object classes, such as a temporary MovieClip I made, or a Shape, but nothing shows up, so I know it has nothing to do with it being a Bitmap.
As you stated
This is in a class constructor for a class called block, block_maker
is the object that called the constructor, an instance of level.
this.bitmap = new Bitmap(this.bitmap_data);
this.addChild(this.bitmap);
this.block_maker.stage_foreground.addChild(this);
The level class needs to to extend a display object for it to show up.
In other words
"this"
has to be a display object or extend it in some form.
The reason this doesn't work.
this.block_maker.stage_foreground.addChild(this);
and this does
this.block_maker.stage_foreground.addChild(this.bitmap);
Is because "this" is not a display object but "this.bitmap" is.
The DisplayObject class is the base class for all objects that can be placed on the display list.
First of all, even though it's not neccesary, I'd suggest to make a classname start with a capital letter, and vars always start with a lower-case letter. It's a common 'rule' in AS3 that's mainly to avoid confusion.
The problem most likely lies within you use of this; what you're doing is adding this into this. It seems to me it's not a proper way of coding.
Also, since all of the other attempts didn't work; have you tried to make the var you want ot add a public static var?

AS3 Custom Depth Control

I am trying to create a way of controlling movieclip depths, which movieclip is show above another, so that I can set the depth of a movieclip to any number and they will be displayed with higher values above lower values.
I was thinking of creating a MovieClipDepth class that extends MovieClip with the added property depth, and a Container class that extends DisplayObjectContainer which all objects will be placed inside of.
The Container class will override the addChild method to update the child display order when a child is added.
What I need help with is how do I reorder the children according to
their depth value?
As you can read in the comment below your question, there are several methods for this.
But actually, what you asked "set the depth of a movieclip to any number" can't really be done in AS3. If i'm correct, you could do this in AS2, so...
... how was it ...
_root.createEmptyMovieClip("mc", -1000);
or
_root.createEmptyMovieClip("mc1", 1);
_root.createEmptyMovieClip("mc2", 10);
worked, but does not work in AS3. In AS3 depth starts with 0 and you can't force a DisplayObject to sit on a level what is not continous from zero.
So the depths' of 3 movieclips in a container is only possible with these values: 0, 1, 2.
Depth can't be a negative number for example.
Now, if you want to build a custom depth manager, you can do that, but you have to consider these facts.
So to say, you could create virtual depths.
So I guess, you could override the addChildAt method for example. At the moment, if you would give a wrong number: negative, or higher then the number of children, flash would give back the error:
RangeError: Error #2006: The supplied index is out of bounds.
So mc.addChildAt(newchild, -1000) gives an arror.
But with overriding the method, you could make a trick, so you could store the depths in an array. You could store any numbers and then transform that order for the needs of AS3.
Like pairing the depths with the added children, sorting the array by the depths, then manage the children according to the order.
If you have more questions, feel free to ask, hope this gets you closer to the solution.
I suggest you take a look at this tutorial :
A Tour of Depths Management Methods on the website http://www.flashandmath.com/. I presume you not a newbie .
The link is this:
http://www.flashandmath.com/intermediate/depths/index.html