topical media & game development
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#javascript-processing-example-basic-color-lineargradient.htm / htm



  <!DOCTYPE html>
  <html><head>
  
  <script src="javascript-processing-example-processing.js"></script>
  <script src="javascript-processing-example-init.js"></script>
  <link rel="stylesheet" href="javascript-processing-example-style.css">
  </head><body><h1><a href="http://ejohn.org/blog/processingjs/">Processing.js</a></h1>
  <h2>LinearGradient</h2>
  
  <p>by Ira Greenberg. 
  
  Using the convenient red(), green() 
  and blue() component functions,
  generate some linear gradients.</p>
  
  <p><a href="http://processing.org/learning/basics/lineargradient.html"><b>Original Processing.org Example:</b> LinearGradient</a><br>
  <script type="application/processing">
  // constants
  int Y_AXIS = 1;
  int X_AXIS = 2;
  
  void setup(){
    size(200, 200);
  
    // create some gradients
    // background
    color b1 = color(190, 190, 190);
    color b2 = color(20, 20, 20);
    //setGradient(0, 0, width, height, b1, b2, Y_AXIS);
    //center squares
    color c1 = color(255, 120, 0);
    color c2 = color(10, 45, 255);
    color c3 = color(10, 255, 15);
    color c4 = color(125, 2, 140);
    color c5 = color(255, 255, 0);
    color c6 = color(25, 255, 200);
    setGradient(25, 25, 75, 75, c1, c2, Y_AXIS);
    setGradient(100, 25, 75, 75, c3, c4, X_AXIS);
    setGradient(25, 100, 75, 75, c2, c5, X_AXIS);
    setGradient(100, 100, 75, 75, c4, c6, Y_AXIS);
  }
  
  void setGradient(int x, int y, float w, float h, color c1, color c2, int axis ){
    // calculate differences between color components 
    float deltaR = red(c2)-red(c1);
    float deltaG = green(c2)-green(c1);
    float deltaB = blue(c2)-blue(c1);
  
    // choose axis
    if(axis == Y_AXIS){
      /*nested for loops set pixels
       in a basic table structure */
      // column
      for (int i=x; i<=(x+w); i++){
        // row
        for (int j = y; j<=(y+h); j++){
          color c = color(
          (red(c1)+(j-y)*(deltaR/h)),
          (green(c1)+(j-y)*(deltaG/h)),
          (blue(c1)+(j-y)*(deltaB/h)) 
            );
          set(i, j, c);
        }
      }  
    }  
    else if(axis == X_AXIS){
      // column 
      for (int i=y; i<=(y+h); i++){
        // row
        for (int j = x; j<=(x+w); j++){
          color c = color(
          (red(c1)+(j-x)*(deltaR/h)),
          (green(c1)+(j-x)*(deltaG/h)),
          (blue(c1)+(j-x)*(deltaB/h)) 
            );
          set(j, i, c);
        }
      }  
    }
  }
  </script><canvas width="200" height="200"></canvas></p>
  <div style="overflow: hidden; height: 0px; width: 0px;"></div>
  
  <pre><b>// All Examples Written by <a href="http://reas.com/">Casey Reas</a> and <a href="http://benfry.com/">Ben Fry</a>
  // unless otherwise stated.</b>
  // constants
  int Y_AXIS = 1;
  int X_AXIS = 2;
  
  void setup(){
    size(200, 200);
  
    // create some gradients
    // background
    color b1 = color(190, 190, 190);
    color b2 = color(20, 20, 20);
    setGradient(0, 0, width, height, b1, b2, Y_AXIS);
    //center squares
    color c1 = color(255, 120, 0);
    color c2 = color(10, 45, 255);
    color c3 = color(10, 255, 15);
    color c4 = color(125, 2, 140);
    color c5 = color(255, 255, 0);
    color c6 = color(25, 255, 200);
    setGradient(25, 25, 75, 75, c1, c2, Y_AXIS);
    setGradient(100, 25, 75, 75, c3, c4, X_AXIS);
    setGradient(25, 100, 75, 75, c2, c5, X_AXIS);
    setGradient(100, 100, 75, 75, c4, c6, Y_AXIS);
  }
  
  void setGradient(int x, int y, float w, float h, color c1, color c2, int axis ){
    // calculate differences between color components 
    float deltaR = red(c2)-red(c1);
    float deltaG = green(c2)-green(c1);
    float deltaB = blue(c2)-blue(c1);
  
    // choose axis
    if(axis == Y_AXIS){
      /*nested for loops set pixels
       in a basic table structure */
      // column
      for (int i=x; i&lt;=(x+w); i++){
        // row
        for (int j = y; j&lt;=(y+h); j++){
          color c = color(
          (red(c1)+(j-y)*(deltaR/h)),
          (green(c1)+(j-y)*(deltaG/h)),
          (blue(c1)+(j-y)*(deltaB/h)) 
            );
          set(i, j, c);
        }
      }  
    }  
    else if(axis == X_AXIS){
      // column 
      for (int i=y; i&lt;=(y+h); i++){
        // row
        for (int j = x; j&lt;=(x+w); j++){
          color c = color(
          (red(c1)+(j-x)*(deltaR/h)),
          (green(c1)+(j-x)*(deltaG/h)),
          (blue(c1)+(j-x)*(deltaB/h)) 
            );
          set(j, i, c);
        }
      }  
    }
  }</pre>
  
  </body></html>
[] readme course(s) preface I 1 2 II 3 4 III 5 6 7 IV 8 9 10 V 11 12 afterthought(s) appendix reference(s) example(s) resource(s) _

(C) Æliens 20/2/2008

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