   Dynamic Alpha Map Generation
  I have a flat terrain which is 32x32 and each tile is 16 pixels wide. Ive implemented the ability to do texture splatting in irrlicht via a shader but the problem with this is i only use a static alphamap that my program loads in. I would like to know how i could go about generating the alphamap based on mouse clicking and dragging. Any help or links to resources would be greatly appreciatedThanks   
  Assign each tile vertex in your terrain a pixel in an alphamap (per texture).  Then just sample from this alphamap when you render the terrain.  When you're in the middle of a tile, it will automatically do the bilinear filtering between pixels corresponding tile tile vertices.   