CODEWITHSUNDEEP
unity-game-engine
Philip Kirkbride
Philip Kirkbride

Reputation: 22879

Get volume of an object in Unity3D

I'm writing a script for an Object in Unity3D.

I want to get the volume of my object.

rigidBody = GetComponent<Rigidbody>();

I'm looking in the documentation at the attributes contained in Rigidbody but I don't see anything I can use.

I tried using bounds but I found that rotation of an object changed those values even without size changing:

int getSize(Vector3 bounds)
{
    float size = bounds[0] * bounds[1] * bounds[2] * 1000;
    Debug.Log("size value = " + (int)size);
    return (int)size;
}

What properties can I use to calculate the volume of an object?

Upvotes: 3

Views: 5567

Answers (1)

Iggy
Iggy

Reputation: 4888

The math is explained here.

In C# for convencience:

float SignedVolumeOfTriangle(Vector3 p1, Vector3 p2, Vector3 p3)
{
    float v321 = p3.x * p2.y * p1.z;
    float v231 = p2.x * p3.y * p1.z;
    float v312 = p3.x * p1.y * p2.z;
    float v132 = p1.x * p3.y * p2.z;
    float v213 = p2.x * p1.y * p3.z;
    float v123 = p1.x * p2.y * p3.z;
    return (1.0f / 6.0f) * (-v321 + v231 + v312 - v132 - v213 + v123);
}

float VolumeOfMesh(Mesh mesh)
{
    float volume = 0;
    Vector3[] vertices = mesh.vertices;
    int[] triangles = mesh.triangles;
    for (int i = 0; i < mesh.triangles.Length; i += 3)
    {
        Vector3 p1 = vertices[triangles[i + 0]];
        Vector3 p2 = vertices[triangles[i + 1]];
        Vector3 p3 = vertices[triangles[i + 2]];
        volume += SignedVolumeOfTriangle(p1, p2, p3);
    }
    return Mathf.Abs(volume);
}

Mesh mesh = GetComponent<MeshFilter>().sharedMesh;
Debug.Log(VolumeOfMesh(mesh));

Upvotes: 3

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