update readme

add information about the project

README.md

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-# Water Ripple - Animation of a water ripple effect over an selected image using Qt Widgets
+# Water Ripple
+
+## Animation of a water ripple effect over an selected image using Qt Widgets
+
+The idea and some of the code were copied from: http://agilerepose.weebly.com/water-ripple.html
+
+Example of the application:
+
+![](https://github.com/sfadiga/WaterRipple/blob/master/anim.gif)
+
+the idea behind this code is to update a pixel table from the original image making the origin of the efect in (x,y) to propagate changes on the pixels in 4 directions, basically a loop updates the frame buffer using the following pseudo-code:
+
+```
+
+damping = some non-integer between 0 and 1
+
+  begin loop 
+      for every non-edge element:
+      loop
+          Buffer2(x, y) = (Buffer1(x-1,y)
+                           Buffer1(x+1,y)
+                           Buffer1(x,y+1)
+                           Buffer1(x,y-1)) / 2 - Buffer2(x,y)
+ 
+          Buffer2(x,y) = Buffer2(x,y) * damping
+      end loop
+
+      Display Buffer2
+      Swap the buffers 
+
+  end loop
+
+```
+the original idea is well explained here:
+https://web.archive.org/web/20160418004149/http://freespace.virgin.net/hugo.elias/graphics/x_water.htm