Game help

[HelenI]

Hey! I'm helping a friend with a game and i have a very BIG problem. I have to check if the object1 is over the object2 (object1 collide with object 2).
note:on the code below i will skip some lines of my original code

IModel* Marble = marbleMesh->CreateModel(0, 0, 0);
IModel* Mushroom1 = mushroomMesh->CreateModel(-70, 0, 90);
//here i get the coordinates of the marble after moving around
  Dx = bullet->GetX() - marble->GetX(); 
  Dz = bullet->GetZ() - marble->GetZ();
//next i have to check if the coordinates of the marble are
 the same of the mushroom but i don't know how to do that 

[Smac89]

if (bullet->GetX() == marble->GetX() && bullet->GetY() == marble->GetY()) {
    float bz = bullet->GetZ();
    float mz = marble.GetZ();
    return bz >= mz ? 0 <= bz - mz && (bz - mz) <= someThreshold : false;
}

So as you can see to do this correctly, you need to define some threshold to be distance that the bullet must be from the target to correctly say that a hit has occurred.
This threshold value should be the maximum distance the bullet moves for each tick of the game.

[HelenI]

hi! the bullet is the same object with the marble...i have to find if the marble-bullet collide with the mushroom. I'm trying to find a way so i can get the x and z of the mushroom and check if the marble coordinates are the same with the mushroom coordinates....
for example:
these are the coordinates of the mushroom

IModel* Mushroom1 = mushroomMesh->CreateModel(-70, 0, 90);

i move the marble-bullet and i have to find if the marble-bullet has collided with the mushroom