CODEWITHSUNDEEP
c#arraysunity-game-engine
ctwheels
ctwheels

Reputation: 22837

Programmatically create a 3D prism from location of its vertices

I am working on a project in Unity 4.6. I am wondering if there is an easy way to programmatically set the vertex locations. Currently my code looks like this (C#):

public void createPoints(float x, float y, float z) {
    point [0] = new Vector3 (x, y, z);
    point [1] = new Vector3 (x, y, -z);
    point [2] = new Vector3 (x, -y, z);
    point [3] = new Vector3 (x, -y, -z);
    point [4] = new Vector3 (-x, y, z);
    point [5] = new Vector3 (-x, y, -z);
    point [6] = new Vector3 (-x, -y, z);
    point [7] = new Vector3 (-x, -y, -z);
}

Where x, y, and z are predetermined values and point is a Vector3[] (array). The prism's centre is to be point 0,0,0 (Vector3(0,0,0) in Unity).

As an example, using the following values:

The points generated should be the following (order does not matter):

  1. (1,2,3)
  2. (1,2,-3)
  3. (1,-2,3)
  4. (1,-2,-3)
  5. (-1,2,3)
  6. (-1,2,-3)
  7. (-1,-2,3)
  8. (-1,-2,-3)

My question: Is there a way to generate these points without practically hardcoding the values in?

My current code for the desired solution is:

public void createPoints(float originalX, float originalY, float originalZ) {
    for (int i = 0; i < 8; i++) { //8 vertices exist of a rectangular prism
        point [i] = new Vector3 (x, y, z);
    }
}

How do I change this code to generate these positive and negative points? My guess is some sort of alternation between positive and negative values for x, y, and z, using modulus of i or rounding of the division of i by some other integer, however I cannot wrap my brain around it. C# or UnityScript are OK.

In other words, in each iteration of the for loop, x = -x, for each something y = -y, for each something z = -z.

Any help with this is greatly appreciated.

Upvotes: 1

Views: 286

Answers (3)

Harold Ship
Harold Ship

Reputation: 1019

I don't know how if my Unity syntax is correct, but this code should be modifiable to work there. Basically, it gives you 8 vectors. The x values are x, -x, x, -x, ... The y values are y, y, -y, -y, y, y, ... and the z values are z, z, z, z, -z, -z, -z, -z. This is done by multiplying by -1 to even and odd powers.

function createPoints(x, y, z) {
  var resp = [];
  for (var i = 0; i < 8; ++i) {
    var vect = new Vector3d(x * Math.pow(-1, i), y * Math.pow(-1, Math.floor(i / 2)), z * Math.pow(-1, Math.floor(i / 4)));
    resp.push(vect);
  }
  return resp;
}

createPoints(1,2,3);

Upvotes: 1

EZI
EZI

Reputation: 15364

I would use linq for this

var alt = new[] { 1, -1 };
var result = ( from i in alt
               from j in alt
               from k in alt
               select new Vector3(i * 1, j * 2, k * 3)
              ).ToList();

Upvotes: 3

Jacob Lambert
Jacob Lambert

Reputation: 7679

You can do this with nested for loops like so:

List<Vector3> points = new List<Vector3>();

for (int i = 0; i < 2; i++)
    for (int j = 0; j < 2; j++)
        for (int k = 0; k < 2; k++)
            points.Add(new Vector3(i == 0 ? originalX : -originalX,
                                   j == 0 ? originalY : -originalY,
                                   k == 0 ? originalZ : -originalZ));

Vector3[] point = points.ToArray();

There probably is an easier, cleaner way to do this, but it does work.

Upvotes: 3

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