title: How to calculate the blast area of a bomb?
body: <p>I'm developing a game, let's say player a put a bomb in location x=100,y=100 and the explosion radius is 100 units... It is pretty easy for me to find all the "items" in the game that were hit by the blast of the bomb (just need to check that their distance from the bomb is lower then 100).</p>
  
  <p>But now i want to take in consideration the obstacles i have in the game, the obstacles are squares, always 64*64 pixels, always aligned to the axis (not rotated).. i want to know if an item was "hidden" behind an obstacle to know he wasn't hit ... </p>
  
  <p>something like this : </p>
  
  <p><img src="https://i.stack.imgur.com/3FzHd.png" alt="enter image description here"> </p>
  
  <p>The dude on the right wasn't hit, but the dude on the bottom was hit, i filled in gray the hit area, and in green the area which is hidden... </p>
  
  <p>My idea is : 
  1. find all the items in the scene that their distance from the bomb is lower then 100.
  2. find all the obstacles in the scene that their distance from the bomb is lower then 100.
  3. calculate the lines from the items to the center of the bomb .. then check if the lines intersect any obstacle , if no .. you were hit.</p>
  
  <p>Finaly, the questions 
  1. Does any one has a better idea ? 
  2. Are there free opensource c# compatible engines that can help me ? Box2d can help me here ? </p>
  
  <p>Thanks</p>