具有顶点坐标的3D中的Java碰撞检测

Question

so I've setup all things to presumably create a collision detection, however I'm quite at a loss as to how I would ckeck for collision..

So from my object I've got a bunch of variables with which I could work with but for a simple BoundingBox I would probably only need these here:

System.out.println("width: " + width);
System.out.println("height: " + height);
System.out.println("depth: " + depth);
System.out.println("center[" + xPos+ "/" +yPos+ "/" +zPos+"]");

So what I want is some code that allows me to ckeck if two BoundingBoxes interesct each other, it shouldn't be too hard to come up with a code for this but I'm really struggling with this one, so I would appreciate any help!

I will have two aabb's with mentionned properties:

private void AABB_1()
}
// (width,height,depth,xPos,yPos,zPos)
}

private void AABB_2()
}
// (width,height,depth,xPos,yPos,zPos)
}

In the BoundingBox method I want to check for interesction of the two aabb's and set a boolean to either false or true:

public void BoundingBox()
{
    AABB_1();
    AABB_2();

    boolean intersection;

// check if AABB_1 and AABB_2 intersect each other
// If yes set intersection = true
// If no set intersection = false     
} 

Here in the BoundingBox Method would be the collision detection but as I said I do not reall know how I would ckeck for intersection, has anyone an idea?

Answer 1

Consider 1D first:

//(minX---maxX)
//Non overlap cases:
//a: |----|       
//b:       |----|

//a:       |----|
//b: |----|

public static void intersectOnX(a,b){
  if (b.minX > a.maxX || a.minX > b.maxX)
    return false;//no intersect
  else
    return true;//intersect
}

Repeat this for every extra dimension:

public static void intersect(a,b){
  if (!intersectOnX(a,b))
    return false;//no intersect

  if (!intersectOnY(a,b))
    return false;//no intersect

  if (!intersectOnZ(a,b))
    return false;//no intersect

  return true;//intersect!
}

Answer 2

Given that you have a box with a center and three extends, you can also write a Box method

boolean overlaps( Box other ){
    return
        Math.abs(xPos - other.xPos) <= (width + other.width)/2
        &&
        Math.abs(yPos - other.yPos) <= (depth + other.depth)/2
        &&
        Math.abs(zPos - other.zPos) <= (height + other.height)/2;
}

(Check that x,y,z and width, depth, height correlate.)

If you just have some variables storing these 6 + 6 values, you can write the expression as eg

Number x1, y1, z1, w1, d1, h1;
Number x2, y2, z2, w2, d2, h2;

boolean overlaps =
    Math.abs(x1 - x2) <= (w1 + w2)/2
    &&
    Math.abs(y1 - y2) <= (d1 + d2)/2
    &&
    Math.abs(z1 - z2) <= (h1 + h2)/2;