title: In a directx application, find z (terrain) with known location
body: <p>My english knowlage is not good enought to tell my problems. and i am using stackoverflow second time.</p>
  
  <p>i am hooking a directx application, i just can wrote something to screen and get input from screen and other things.</p>
  
  <p>This game has a terrain, and a lot of players. I can directly edit the player location (x, z, y). But when i edit x and z coordinate, the player is flying :) because i don't know how to calculate the y coordinate (terrain height), i can't calculate it.</p>
  
  <p>Player coordinate is 700, 5.41, 600</p>
  
  <p>when game edit it to 800 and 700, game makes y to 6.50</p>
  
  <p>when i edit it to 800 and 700, the y coordinate still 5.41</p>
  
  <p>6.50 is coordinate, height of terrain of (800, 700), 5.41 is 700,600 terrain height.</p>
  
  <p>Is there a any way to get height of the terrain for speficed coordinate?</p>
  
  <p>Thank you much more.</p>