I'm new to game/graphics development and I'm playing around with particles (in 2D). I want to draw particles close to each other as a blob, just as liquid/water. I do not want to draw big circles overlapping as the blob won't be smooth (and too big). I don't really know physics but I assume what I want is something looking similar to surface tension. I haven't been able to find anything on stackexchange or on Google (maybe I do not know the correct keywords?). So far I have found two possible solutions, but I am unable to find any concrete information about algorithms. One of them is to calculate the concave hull of particles I consider being a blob. I can calculate the blob by creating an equivalence class (on the relation "close to each other"). Strangely enough I haven't been able to find any algorithm explaining how to calculate the concave hull. Many posts (and among stackexchange) links to libraries or commercial products that do this (I need libraries to work in C#), but never any algorithm. Also this solution might have a problem with a circle of particles, which would not detect the empty space in the middle. While researching concave hull I stumbled upon something called alpha shapes. Which seems to be exactly what I want to do, however just as with concave hull I haven't found any source explaining how they actually work. I have found some presentation materials but not enough to go on. It's like a big secret everyone knows except me :-/ After calculating the concave hull or alpha shape I want to make it a Bézier curve to make it smooth and nice. Although I do find my approach a bit too complex, maybe I am trying to solve this the wrong way? If you can either suggest any other solution to my problem, or explain the pieces I am missing I would be very happy and grateful :-) Thanks.