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Stimpy83

OpenGL [Stage3D] Simple Target Camera / PointAt

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Hi,

i'm having a really big problem to understand the pointAt function from stage3d. I think that pointAt does the same like lookAt in OpenGL - But i don't get it right.

Target:

I need a simple Camera with a target, like a target camera in 3D Max or Blender... something like this:

[img]http://www.nord5.de/camera.png[/img]
And my Code is - So i understand the function:

[source lang="java"]view.identity();

target.x = position.x;
target.y = position.y;
target.z = 0;

view.appendTranslation( -position.x, -position.y, -position.z);

view.pointAt( target,
at,
up
);

view.invert();

// at = 0,1,0
// up = 0,0,1
// Because Z is my UpVector[/source]

So - When i move the camera i don't have a target camera - my map rotates and fly away [img]http://public.gamedev.net//public/style_emoticons/default/sad.png[/img] I really don't understand the parameters for pointAt - Can somebody explain me how pointAt works? The Adobe Docu don't say many....

Big Thanks and sry for my bad english [img]http://public.gamedev.net//public/style_emoticons/default/smile.png[/img]

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[source lang="jscript"]package
{
import flash.display.Graphics;
import flash.display.Sprite;
import flash.events.Event;
import flash.geom.Matrix3D;
import flash.geom.Point;
import flash.geom.Vector3D;

/**
* ...
* @author Petrovic Veljko <designlabz@gmail.com>
*/
public class Main extends Sprite
{
public var target:Sprite = new Sprite();
public var cam:Matrix3D = new Matrix3D();
public var view:Sprite = new Sprite();
public function Main():void
{
var g:Graphics;

//draw top face
var up:Sprite = new Sprite();
g = up.graphics;
g.beginFill(0x7878FF,.5);
g.drawRect( -200, -200, 400, 400);

//draw bottom face
var dn:Sprite = new Sprite();
g = dn.graphics;
g.beginFill(0xFF00FF,.8);
g.drawRect( -200, -200, 400, 400);
g.endFill();
//draw arrow pointing up on screen (Y-)
g.lineStyle(2);
g.moveTo(-200, 0);
g.lineTo(0, 200);
g.lineTo(200, 0);

//draw axes
g = view.graphics;
// X
g.lineStyle(2, 0xff0000);
g.moveTo(-500, -1000);
g.lineTo( -500, 1000);
g.moveTo(0, -1000);
g.lineTo(0, 1000);
g.moveTo(500, -1000);
g.lineTo( 500, 1000);
// Y
g.lineStyle(2, 0x00FF00);
g.moveTo( -1000, -500);
g.lineTo(1000, -500);
g.moveTo( -1000, 0);
g.lineTo(1000, 0);
g.moveTo( -1000, 500);
g.lineTo(1000, 500);

//add faces to 3D object
dn.z = -200;
target.addChild(dn);
up.z = 200;
target.addChild(up);

//add object to view
view.addChild(target);

if (stage) init();
else addEventListener(Event.ADDED_TO_STAGE, init);
}

private function init(e:Event = null):void
{
removeEventListener(Event.ADDED_TO_STAGE, init);
addEventListener(Event.ENTER_FRAME, tock);

//activate 3D mode on view
view.transform.matrix3D = new Matrix3D();
view.transform.matrix3D.identity();
//add view to stage
addChild(view);
}

private function tock(e:Event = null):void {

//get mouse offset from the center
var o:Point = new Point();
o.x = (stage.stageWidth / 2 - mouseX);
o.y = (stage.stageHeight / 2 - mouseY);

//move cam
cam.position = new Vector3D(5* -o.x, 5* o.y, 1000);

cam.pointAt(
new Vector3D( 0, 0, 0), //point in world space to look at
Vector3D.Z_AXIS, //side of 3D objec facing up in world space
Vector3D.Y_AXIS //where should our arrow point
);
//reset view
view.transform.matrix3D.identity();

//cam
view.transform.matrix3D.append(cam);
view.transform.matrix3D.invert();
//center view
view.transform.matrix3D.appendTranslation(stage.stageWidth / 2, stage.stageHeight / 2, 1);
}
}
}[/source] Edited by DLabz

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