marți, 20 septembrie 2016

Mandelbrot with three.js .

The Mandelbrot set is the set of complex numbers c for which the function f c ( z ) = z 2 + c . - wikipedia.org

You need to download the three.js - java script from threejs webpage.
The source code is simple. Come with default HTML5 page and javascripts.
One part of this will make vertex-shader and fragment shader, both is 2D shader type.
You need the canvas tag with id="canv".
The last part of source code is make to put all into one image processing by shaders.
You can read this tutorial here.

 <!DOCTYPE html>  
 <html>  
 <head>  
 <meta charset="UTF-8">  
 <title>Title of the document</title>  
 <script src="three.js"></script>  
 </head>  
 <body>  
   
 <canvas id="canv" width="640" height="480"></canvas>  
   
 <script id="2d-vertex-shader" type="x-shader/x-vertex">  
 attribute vec2 a_position;  
  void main() {  
   gl_Position = vec4(a_position, 0, 1);  
  }  
 </script>  
   
 <script id="2d-fragment-shader" type="x-shader/x-fragment">  
  #ifdef GL_FRAGMENT_PRECISION_HIGH  
   precision highp float;  
  #else  
   precision mediump float;  
  #endif  
  #define PI 3.14159  
   
 float hash( float n ) { return fract(sin(n)*753.5453123); }  
   
 #define NUM_STEPS  50  
  #define ZOOM_FACTOR 2.0  
  #define X_OFFSET  0.5  
   
  #ifdef GL_FRAGMENT_PRECISION_HIGH  
   precision highp float;  
  #else  
   precision mediump float;  
  #endif  
  precision mediump int;  
   
  void main() {  
   vec2 z;  
   float x,y;  
   int steps;  
   float normalizedX = (gl_FragCoord.x - 320.0) / 640.0 * ZOOM_FACTOR *  
             (640.0 / 480.0) - X_OFFSET;  
   float normalizedY = (gl_FragCoord.y - 240.0) / 480.0 * ZOOM_FACTOR;  
   
   z.x = normalizedX;  
   z.y = normalizedY;  
   
   for (int i=0;i<NUM_STEPS;i++) {  
   
   steps = i;  
   
     x = (z.x * z.x - z.y * z.y) + normalizedX;  
     y = (z.y * z.x + z.x * z.y) + normalizedY;  
   
     if((x * x + y * y) > 4.0) {  
      break;  
     }  
   
     z.x = x;  
     z.y = y;  
   
   }  
   
   if (steps == NUM_STEPS-1) {  
    gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0);  
   } else {  
    gl_FragColor = vec4(0.0, 0.0, 0.0, 1.0);  
   }  
  }  
 </script>  
 <script type="text/javascript">  
 var gl;  
 var canvas;  
 var buffer;  
  window.onload = init;  
    
  function init() {  
    
   
   canvas    = document.getElementById('canv');  
   gl      = canvas.getContext('experimental-webgl');  
   canvas.width = 640;  
   canvas.height = 480;  
    
   gl.viewport(0, 0, gl.drawingBufferWidth, gl.drawingBufferHeight);  
   
 var shaderScript;  
 var shaderSource;  
 var vertexShader;  
 var fragmentShader;  
   
  buffer = gl.createBuffer();  
  gl.bindBuffer(gl.ARRAY_BUFFER, buffer);  
  gl.bufferData(  
   gl.ARRAY_BUFFER,   
   new Float32Array([  
    -1.0, -1.0,   
     1.0, -1.0,   
    -1.0, 1.0,   
    -1.0, 1.0,   
     1.0, -1.0,   
     1.0, 1.0]),   
   gl.STATIC_DRAW  
  );  
   
   render();  
    
  }  
    
 function render() {  
    
   window.requestAnimationFrame(render, canvas);  
    
   gl.clearColor(1.0, 0.0, 0.0, 1.0);  
   gl.clear(gl.COLOR_BUFFER_BIT);  
   
  shaderScript = document.getElementById("2d-vertex-shader");  
  shaderSource = shaderScript.text;  
  vertexShader = gl.createShader(gl.VERTEX_SHADER);  
  gl.shaderSource(vertexShader, shaderSource);  
  gl.compileShader(vertexShader);  
   
  shaderScript  = document.getElementById("2d-fragment-shader");  
  shaderSource  = shaderScript.text;  
  fragmentShader = gl.createShader(gl.FRAGMENT_SHADER);  
  gl.shaderSource(fragmentShader, shaderSource);  
  gl.compileShader(fragmentShader);  
   
  program = gl.createProgram();  
  gl.attachShader(program, vertexShader);  
  gl.attachShader(program, fragmentShader);  
  gl.linkProgram(program);   
  gl.useProgram(program);  
  positionLocation = gl.getAttribLocation(program, "a_position");  
  gl.enableVertexAttribArray(positionLocation);  
  gl.vertexAttribPointer(positionLocation, 2, gl.FLOAT, false, 0, 0);  
   
  gl.drawArrays(gl.TRIANGLES, 0, 6);  
  }  
 </script>  
 </body>  
 </html>   

Niciun comentariu:

Trimiteți un comentariu