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Droste / Escher Effect in AGAL

Devon O. · December 31, 2015 · Actionscript, Shaders · 0 comments
50

One last bonus post for the new year, seeing as how I remembered I had a blog. This is really just a snippet I would ordinarily post on Wonderfl, but Wonderfl seems not to be working for me lately (if anyone wants to check out my Wonderfl profile and let me know if they can view any of my posted codes, I’d appreciate it. But I can’t).

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C#
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/**
*    Copyright (c) 2016 Devon O. Wolfgang
*
*    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.
*/
 
package
{
    
import com.adobe.utils.AGALMiniAssembler;
import com.bit101.components.CheckBox;
import com.bit101.components.HUISlider;
import flash.display.Bitmap;
import flash.display.BitmapData;
import flash.display.Loader;
import flash.display.LoaderInfo;
import flash.display.Sprite;
import flash.display.StageAlign;
import flash.display.StageScaleMode;
import flash.display3D.Context3D;
import flash.display3D.Context3DProfile;
import flash.display3D.Context3DProgramType;
import flash.display3D.Context3DRenderMode;
import flash.display3D.Context3DTextureFormat;
import flash.display3D.Context3DVertexBufferFormat;
import flash.display3D.IndexBuffer3D;
import flash.display3D.Program3D;
import flash.display3D.textures.Texture;
import flash.display3D.VertexBuffer3D;
import flash.events.Event;
import flash.geom.Matrix3D;
import flash.net.URLRequest;
import flash.system.LoaderContext;
 
/**
* Zooming Droste effect
* largely ported from http://codepen.io/spleen666/pen/zbhcK
* @author Devon O.
*/
 
[SWF(width='465', height='465', backgroundColor='#000000', frameRate='60')]
public class Main extends Sprite
{
    private static var VERTEX_SHADER:String =
    <![CDATA[
    
    m44 op, va0, vc0
    mov v0, va1
    
    ]]>;
    
    
    private static var FRAGMENT_SHADER:String =
    <![CDATA[
    
    mov ft0.xy, v0.xy
 
    add ft0.xy, ft0.xy, fc2.xy
 
    mul ft1.x, ft0.x, ft0.x
    mul ft1.y, ft0.y, ft0.y
    add ft1.x, ft1.x, ft1.y
    log ft1.x, ft1.x
    mul ft1.x, ft1.x, fc2.z
 
    mov ft2.xy, ft0.xy
 
    // start atan2
    // ft4.x = atan2(ft2.y, ft2.x)  Uses: ft3, ft4, ft5
    add ft2.x, ft2.x, fc1.x
 
    div ft3.x, ft2.y, ft2.x
    neg ft3.y, ft3.x
    
    mul ft4.y, fc1.y, ft3.x
    add ft4.z, fc0.x, ft3.x
    div ft5.x, ft4.y, ft4.z
 
    mul ft4.y, fc1.7, ft3.y
    add ft4.z, fc0.x, ft3.y
    div ft5.y, ft4.y, ft4.z
    
    slt ft4.x, ft2.x, fc0.y
    slt ft4.y, ft2.y, fc0.y
    sub ft4.z, fc0.x, ft4.x
    sub ft4.w, fc0.x, ft4.y
    
    mul ft3.x, ft4.z, ft4.w
    mul ft3.y, ft4.x, ft4.w
    mul ft3.z, ft4.x, ft4.y
    mul ft3.w, ft4.z, ft4.y
    
    sub ft4.x, ft5.x, fc0.z
    neg ft4.y, ft5.y        
    mov ft4.z, ft5.x
    sub ft4.w, fc0.z, ft5.y
    
    mul ft4, ft4, ft3
    
    add ft4.xy, ft4.xz, ft4.yw
    add ft4.x, ft4.x, ft4.y
 
    // eo atan2
 
    mov ft1.y, ft4.x
 
    mov ft2.x, fc3.w
 
    mov ft2.y, fc3.y
    log ft2.y, ft2.y
    div ft2.y, ft2.y, fc0.w
    mul ft2.y, ft2.y, fc3.z
    neg ft2.y, ft2.y
 
    mul ft3.x, ft1.x, ft2.x
    mul ft3.y, ft1.y, ft2.y
    sub ft3.x, ft3.x, ft3.y
 
    mul ft4.x, ft1.x, ft2.y
    mul ft4.y, ft1.y, ft2.x
    add ft3.y, ft4.x, ft4.y
 
    neg ft4.x, ft3.y
    div ft4.x, ft4.x, fc0.w
 
    mov ft4.y, fc3.y
    log ft4.y, ft4.y
    div ft4.y, ft3.x, ft4.y
    sub ft4.y, ft4.y, fc3.x
 
    tex oc, ft4.xy, fs0<2d, wrap, linear, mipnone>
    
    ]]>;
    
    private var context:Context3D;
    private var isReady:Boolean;
    private var program:Program3D;
    private var renderMatrix:Matrix3D;
    private var vertexBuffer:VertexBuffer3D;
    private var indexBuffer:IndexBuffer3D;
    private var textureData:BitmapData;
    private var texture:Texture;
    private var textureWidth:int;
    private var textureHeight:int;
    
    private var zoomControl:HUISlider;
    private var autoZoom:Boolean=true;
    
    public function Main():void
    {
        if (stage) init();
        else addEventListener(Event.ADDED_TO_STAGE, init);
    }
    
    private function init(e:Event = null):void
    {
        removeEventListener(Event.ADDED_TO_STAGE, init);
        
        stage.scaleMode = StageScaleMode.NO_SCALE;
        stage.align = StageAlign.TOP_LEFT;
        this.isReady = false;
        this.renderMatrix = new Matrix3D();
        
        loadImage();
        startRender();
    }
    
    private function loadImage():void
    {
        var l:Loader = new Loader();
        l.contentLoaderInfo.addEventListener(Event.COMPLETE, onImageLoad);
        var path:String = "http://assets.wonderfl.net/images/related_images/1/12/1247/124761a085cc7a1704c9fb601fe9d35e2e5a8b2e";
        l.load(new URLRequest(path), new LoaderContext(true));
    }
    
    private function onImageLoad(event:Event=null):void
    {
        event.currentTarget.removeEventListener(Event.COMPLETE, onImageLoad);
        var l:Loader = (event.currentTarget as LoaderInfo).loader;
        this.textureData = (l.content as Bitmap).bitmapData;    
        
        requestContext();
    }
    
    private function startRender():void
    {
        addEventListener(Event.ENTER_FRAME, onFrame);
    }
    
    private function requestContext():void
    {
        stage.stage3Ds[0].addEventListener(Event.CONTEXT3D_CREATE, onStage3dContext);
        stage.stage3Ds[0].requestContext3D(Context3DRenderMode.AUTO, Context3DProfile.BASELINE);
    }
    
    private function onStage3dContext(e:Event):void
    {
        this.context = stage.stage3Ds[0].context3D;
        this.context.configureBackBuffer(stage.stageWidth, stage.stageHeight, 2, false, false);
        
        createVertexBuffer();
        createIndexBuffer();
        createTextures();
        createPrograms();
        createControls();
        
        this.isReady = true;
    }
    
    private function createVertexBuffer():void
    {
        var vertices:Vector. = new [
        //    x            y        u  v
            -1.0,         1.0,      0, 0,
             1.0,         1.0,      1, 0,
            -1.0,        -1.0,      0, 1,
             1.0,        -1.0,      1, 1  ];
            
        this.vertexBuffer = this.context.createVertexBuffer(4, 4);
        this.vertexBuffer.uploadFromVector(vertices, 0, 4);
    }
    
    private function createIndexBuffer():void
    {
        this.indexBuffer = this.context.createIndexBuffer(6);
        
       // 2 triangles (0, 1, 2) &amp; (1, 3, 2)
       //   0 - 1
       //   | / |
       //   2 - 3
        this.indexBuffer.uploadFromVector(new [0, 1, 2,   1, 3, 2], 0, 6);
    }
    
    private function createTextures():void
    {
        this.textureWidth = this.textureData.width;
        this.textureHeight = this.textureData.height;
        this.texture = this.context.createTexture(this.textureWidth, this.textureHeight, Context3DTextureFormat.BGRA, false);
        this.texture.uploadFromBitmapData(this.textureData);
        this.textureData.dispose();
    }
 
    private function createPrograms():void
    {
        var vertexShaderAssembler:AGALMiniAssembler = new AGALMiniAssembler();
        vertexShaderAssembler.assemble(Context3DProgramType.VERTEX, VERTEX_SHADER);
        
        var fragmentShaderAssembler:AGALMiniAssembler = new AGALMiniAssembler();
        fragmentShaderAssembler.assemble(Context3DProgramType.FRAGMENT, FRAGMENT_SHADER);
        
        this.program = this.context.createProgram();
        this.program.upload(vertexShaderAssembler.agalcode, fragmentShaderAssembler.agalcode);
    }
    
    private function createControls():void
    {
        var s1:HUISlider = new HUISlider(this, 5, 5, "Radius1", function(e:Event):void { radius1 = s1.value; } );
        s1.minimum = -10.0;
        s1.maximum = 10.0;
        s1.tick = 1.0;
        s1.value = -1.0;
        
        var s2:HUISlider = new HUISlider(this, 5, 20, "Radius2", function(e:Event):void { radius2 = s2.value; } );
        s2.minimum = -10.0;
        s2.maximum = 10.0;
        s2.tick = 1.0;
        s2.value = -2.0;
        
        var s3:HUISlider = new HUISlider(this, 5, 35, "Center X", function(e:Event):void { centerX = s3.value; } );
        s3.minimum = 0.0;
        s3.maximum = 1.0;
        s3.tick = .025;
        s3.value = 0.50;
        
        var s4:HUISlider = new HUISlider(this, 5, 50, "Center Y", function(e:Event):void { centerY = s4.value; } );
        s4.minimum = 0.0;
        s4.maximum = 1.0;
        s4.tick = .025;
        s4.value = .50;
        
        var s5:HUISlider = new HUISlider(this, 5, 65, "Scale", function(e:Event):void { _scale = s5.value; } );
        s5.minimum = 10.0;
        s5.maximum = 256.0;
        s5.tick = 1.0;
        s5.value = 128;
        
        this.zoomControl = new HUISlider(this, 5, 80, "Zoom", function(e:Event):void { zoom = zoomControl.value; } );
        zoomControl.minimum = 0.0;
        zoomControl.maximum = 10;
        zoomControl.tick = .025;
        
        var cb:CheckBox = new CheckBox(this, 5, 95, "Auto Zoom", function(e:Event):void { autoZoom = cb.selected; } );
        cb.selected = true;
    }
    
    private var radius1:Number = -2.0;
    private var radius2:Number = 5.0;
    
    private var centerX:Number = 0.50;
    private var centerY:Number = 0.50;
    
    private var zoom:Number = 0.0;
    private var _scale:Number = 256.0;
 
    private var fc0:Vector. = new [1.0, 0.0, Math.PI, 2*Math.PI];
    private var fc1:Vector. = new [1e-10, Math.PI/2, 0.0, 1.0];
    private var fc2:Vector. = new [0.0, 0.0, .50, -.50];
    private var fc3:Vector. = new [0.0, 0.0, 0.0, 0.0];
    
    private function onFrame(e:Event):void
    {
        if (!this.isReady)
            return;
            
        this.context.clear(0, 0, 0, 1);
        
        this.renderMatrix.identity();
        this.renderMatrix.appendScale(this.textureWidth / stage.stageWidth, this.textureHeight / stage.stageHeight, 1.0);
        this.context.setProgramConstantsFromMatrix(Context3DProgramType.VERTEX, 0, this.renderMatrix, true);
        
        this.context.setVertexBufferAt(0, this.vertexBuffer, 0, Context3DVertexBufferFormat.FLOAT_2);
        this.context.setVertexBufferAt(1, this.vertexBuffer, 2, Context3DVertexBufferFormat.FLOAT_2);
        
        fc2[0] = -centerX;
        fc2[1] = -centerY;
        
        fc3[0] = zoom;
        fc3[1] = _scale;
        fc3[2] = radius1;
        fc3[3] = radius2;
        
        if (this.autoZoom)
        {
            this.zoomControl.value += this.zoomControl.tick;
            if (this.zoomControl.value &gt;= this.zoomControl.maximum)
            {
                this.zoomControl.value = 0.0;
            }
        }
        
        this.context.setProgramConstantsFromVector(Context3DProgramType.FRAGMENT, 0, this.fc0, 1);
        this.context.setProgramConstantsFromVector(Context3DProgramType.FRAGMENT, 1, this.fc1, 1);
        this.context.setProgramConstantsFromVector(Context3DProgramType.FRAGMENT, 2, this.fc2, 1);
        this.context.setProgramConstantsFromVector(Context3DProgramType.FRAGMENT, 3, this.fc3, 1);
        
        this.context.setTextureAt(0, this.texture);
        
        this.context.setProgram(this.program);
        
        this.context.drawTriangles(this.indexBuffer);
        
        this.context.present();
    }
    
}
    
}

Happy New Year!

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Devon O. Wolfgang

AIR | Unity3D | AR/VR

Unity Certified Developer

Technical Reviewer of “The Essential Guide to Flash CS4 AIR Development” and “Starling Game Development Essentials”

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Unity Engineer at Touch Press.

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