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Re: Howto sample a curve?

by Aleksandar Dzeletovic :: Rate this Message:

Aleksandar, I am using your Bezier3D class and it works like a charm. I am using it to map flight trajectories over Yahoo maps API running on Great White.

Thank you for sharing this excellent piece of work!!

Aleksandar Mancic wrote:

Ooops, forgot to attach the Bezier3D class :blush:

There you go...

Aleksandar Mancic wrote:
> If you need a PV3D curve, you can use the attached Bezier3D class. It
> uses multiple Line3D instances (default segmentation is 10) to
> simulate a quadric bezier curve, giving you pretty much the drawing
> API's curveTo() functionality in 3D. Usage is, i hope, quite
> self-explanatory :D
>
> It will also explain you how segmentation is done - just look at the
> build() method. If you want to change the shape of Bezier3D run-time
> (changing properties than calling rebuild() method), you should also
> edit Lines3D class from PV3D and replace it's removeLine() method
> because it doesn't remove vertices when removing a line. Replace the
> removeLine() method with something like:
>
> public function removeLine(line:Line3D):void
> {
> var lineindex : int = lines.indexOf(line);
> if(lineindex>-1)
> {
> var vertices:Array = geometry.vertices;
> var c_v0:int = vertices.indexOf(line.v0);
> if(c_v0 != -1) vertices.splice(c_v0, 1);
> var c_v1:int = vertices.indexOf(line.v1);
> if(c_v1 != -1) vertices.splice(c_v1, 1);
>
> lines.splice(lineindex,1); }
> else if(Papervision3D.VERBOSE)
> {
> trace("Papervision3D Lines3D.removeLine : WARNING
> removal of non-existant line attempted. ");
>
> }
> }
>
> That should do the trick... Until I finish my Graphics3D extension for
> PV3D :)
>
> Cheers...
>
>
> Tim Knip wrote:
>> Hi list,
>>
>> I have a curved line (curveTo)...
>>
>> How to get straight line-segments following this curve?
>> Where start- and endpoints of the segments lie on the curve .
>>
>> Say I have a circle created from 4 curveTo's. How do I create like 16
>> straight line segments?
>>
>> Thanks!
>> Tim
>>
>> _______________________________________________
>> Papervision3D mailing list
>> Papervision3D@osflash.org
>> http://osflash.org/mailman/listinfo/papervision3d_osflash.org
>>
>>
>
>

/*
* Copyright 2008 (c) Aleksandar Mancic, sx@topflashers.com
*
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation
* files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use,
* copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following
* conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*/

/**
* Bezier3D
* Bezier3D for Papervision3D Public Alpha 2.0 - Great White
*
* @author Aleksandar Mancic
* @version 0.0.2
*/

package com.topflashers.ext.pv3d.core.geom.renderables {
import org.papervision3d.core.geom.Lines3D;
import org.papervision3d.core.geom.renderables.Line3D;
import org.papervision3d.core.geom.renderables.Vertex3D;
import org.papervision3d.materials.special.LineMaterial;

public class Bezier3D {

private var _lines:Array;

private var _instance:Lines3D;
private var _material:LineMaterial;

public function Bezier3D(instance:Lines3D, material:LineMaterial, size:Number, segments:int, start:Vertex3D, end:Vertex3D, control:Vertex3D) {

this._instance = instance;
this._material = material;
this.size = size;
this.segments = segments;
this.start = start;
this.end = end;
this.control = control;

rebuild();
}

private var _size:Number = 1;
public function get size():Number {
return _size;
}
public function set size(value:Number):void {
if(value == _size) return;
_size = value;
}

private var _segments:int = 10;
public function get segments():int {
return _segments;
}
public function set segments(value:int):void {
if(value == _segments) return;
_segments = Math.max(1, value);
}

private var _start:Vertex3D;
public function get start():Vertex3D {
return _start;
}
public function set start(value:Vertex3D):void {
if(value === _start) return;
_start = value;
}

private var _end:Vertex3D;
public function get end():Vertex3D {
return _end;
}
public function set end(value:Vertex3D):void {
if(value === _end) return;
_end = value;
}

private var _control:Vertex3D;
public function get control():Vertex3D {
return _control;
}
public function set control(value:Vertex3D):void {
if(value === _control) return;
_control = value;
}

public function rebuild():void {
clear();
build();
}

public function clear():void {
if(_lines && _lines.length) {
var c_len:int = _lines.length;
for(var i:int=0; i<c_len; i++) _instance.removeLine(_lines[i]);
}
_lines = [];
}

private function build():void {
var c_seg:Number, c_dseg:Number, c_sqdseg:Number, c_dbseg:Number, c_pseg:Number;
for(var i:int=0; i<_segments; i++) {
c_seg = i / _segments;
c_dseg = 1 - c_seg;
c_sqdseg = c_dseg * c_dseg;
c_dbseg = 2 * c_seg * c_dseg;
c_pseg = c_seg * c_seg;

var c_p1:Vertex3D = new Vertex3D();
c_p1.x = c_sqdseg * _start.x + c_dbseg * _control.x + c_pseg * _end.x;
c_p1.y = c_sqdseg * _start.y + c_dbseg * _control.y + c_pseg * _end.y;
c_p1.z = c_sqdseg * _start.z + c_dbseg * _control.z + c_pseg * _end.z;

c_seg = (i+1) / _segments;
c_dseg = 1 - c_seg;
c_sqdseg = c_dseg * c_dseg;
c_dbseg = 2 * c_seg * c_dseg;
c_pseg = c_seg * c_seg;

var c_p2:Vertex3D = new Vertex3D();
c_p2.x = c_sqdseg * _start.x + c_dbseg * _control.x + c_pseg * _end.x;
c_p2.y = c_sqdseg * _start.y + c_dbseg * _control.y + c_pseg * _end.y;
c_p2.z = c_sqdseg * _start.z + c_dbseg * _control.z + c_pseg * _end.z;

var c_line:Line3D = new Line3D(_instance, _material, _size, c_p1, c_p2);
_lines.push(c_line);
_instance.addLine(c_line);
}
}
}
}
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