Textfield3D- one sided?

[GBear]

Hi Li

Is it possible to make the Textfield3D one sided, ie to been seen from
the front only?

I tried setting back.visible= false but get error: property is read
only.

I'm planning on using lots of text all around my models and would like
to use this property.

Thanks in advance.

[Li]

Hey GBear,

Textfield3D has bothsides = true by default, that is, backface culling is disabled for text. You can enable it however by setting it to false. This might cause some problems because of the way vector fonts are arbitrarily designed; some glyphs are designed clockwise while others are designed anti clockwise. This orientation in the definition is crucial for back face culling to be implemented properly. There is no convention in font design and I haven't yet produced a solution to counter this.

The back property is not applicable for textfield3d.

I would try using TextField3D with the font you have in mind and bothsides = false and see how many glyphs pop out. It depends on the font really... If you're not ok with that I would go for the Swf.as alternative. Break some text in the Flash IDE and import it in Away3D as a Sprite via Swf.as. There is a slight chance that by doing this (I still haven't tested it enough) Flash will resolve the arbitrary font definitions to its own terms and hence produce more coherent material for the engine.

hth
Li

[GBear]

Thanks Li, I'll give that a go and let you know how it comes out.

Cheers

[Ralph B]

I haven't re-checked this for CS4/FP10, but I understand from the
reasons that Li mentions below, bothsides=false is not always
reliable. If you want the text to be fully rendered when viewed from
the front and invisible when viewed from the rear, you can make both
sides visible, then hide the whole text object if it is facing away
from the camera with an algorithm like this:

function hideReversedTextObject(obj, camPos){
// Does a crude backface culling
var v1:Number3D = new Number3D();
var v2:Number3D = new Number3D();
var ang;

v1 = obj.inverseSceneTransform.forward; // Vector facing away from
object
// Note: use inverseSceneTransform.forward (not
sceneTransform.forward) to get
// the vector that is normal to the plane of the object
(textfield).

v2.sub( obj.scenePosition, camPos ); // vector to camera

ang = Util3.degrees(v2.getAngle(v1)); // Angle between vector to
camera and vector facing away from the object.
obj.visible = (ang < 90);
}

Also, if you look for topic "What is the latest/best/simplest 3d text
method to use?" in the groups I had posted a step-by-step technique
for using TextField3D in CS3, following Li's guidance.

Ralph

[GBear]

Hi Ralph

Yip, it was unreliable, mixing front and back up completely.

Thanks a lot for this, I will give it a go and search through the old
topics.

Cheers

[GBear]

Hey Ralph

My AS3 knowledge is really lean, what's Util3 and how do I set/define
camPos please?

I found the simple/best Text3D topic thanks, and I see you had same
issues as me trying to load font swf. I'm using CS4 and never got it
right from scratch, I just renamed the embedded example and worked
from there.

I also spent half the weekend trying to publish and embed .obj without
luck, Flash seems to be way too tricky with this stuff.

Thankfully Fabrice made Prefab and I managed to get the AS3 export
working, now we just need him to add text interface and we will be
Away :)

Thanks in advance!
G

[Ralph B]

Hi Greg,
Sorry, Util3 is just a class I made for myself of handy utility
functions. The degrees method just converts radians to degrees. You
can replace that line with:

ang = (180/Math.PI)*(v2.getAngle(v1));

Because v1 and v2 are of type Number3D, you can take advantage of the
numerous useful methods in the Number3D class, including getAngle(),
which returns the angle in radians between two vectors that are
characterized by two Number3D objects.

camPos is the x,y,z position of the camera and is of type Number3D.
In Away3D the Camera3D class has a property "position" which is of
type Number3D. I believe the other Away3D cameras inherit from
Camera3D so this property should be available for any camera.

Ralph

[GBear]

Thanks Ralph, I appreciate the help and the rapid response.
Cheers
G