Legacy Documentation: Version 4.5.0

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Matrix4x4.inverse

var inverse: Matrix4x4;
Matrix4x4 inverse;
inverse as Matrix4x4

Description

The inverse of this matrix (Read Only).

Inverted matrix is such that if multiplied by the original would result in identity matrix.

If some matrix transforms vectors in a particular way, then the inverse matrix can transform them back. For example, Transform's worldToLocalMatrix and localToWorldMatrix are inverses of each other.

	// Stretch a mesh at an arbitrary angle around the X axis.
	
	// Angle and amount of stretching.
	var rotAngle: float;
	var stretch: float;
	
	
	private var mf: MeshFilter;
	private var origVerts: Vector3[];
	private var newVerts: Vector3[];
	
	
	function Start () {
		// Get the Mesh Filter component, save its original vertices
		// and make a new vertex array for processing.
		mf = GetComponent.<MeshFilter>();
		origVerts = mf.mesh.vertices;
		newVerts = new Vector3[origVerts.Length];
	}
	
	
	function Update () {
		// Create a rotation matrix from a Quaternion.
		var rot = Quaternion.Euler(rotAngle, 0, 0);
		var m = Matrix4x4.TRS(Vector3.zero, rot, Vector3.one);
		
		// Get the inverse of the matrix (ie, to undo the rotation).
		var inv = m.inverse;
		
		// For each vertex...
		for (var i = 0; i < origVerts.Length; i++) {
			// Rotate the vertex and scale it along its new Y axis.
			var pt = m.MultiplyPoint3x4(origVerts[i]);
			pt.y *= stretch;
			
			// Return the vertex to its original rotation (but with the
			// scaling still applied).
			newVerts[i] = inv.MultiplyPoint3x4(pt);
		}
		
		// Copy the transformed vertices back to the mesh.
		mf.mesh.vertices = newVerts;
	}
using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour {
    public float rotAngle;
    public float stretch;
    private MeshFilter mf;
    private Vector3[] origVerts;
    private Vector3[] newVerts;
    void Start() {
        mf = GetComponent<MeshFilter>();
        origVerts = mf.mesh.vertices;
        newVerts = new Vector3[origVerts.Length];
    }
    void Update() {
        Quaternion rot = Quaternion.Euler(rotAngle, 0, 0);
        Matrix4x4 m = Matrix4x4.TRS(Vector3.zero, rot, Vector3.one);
        Matrix4x4 inv = m.inverse;
        int i = 0;
        while (i < origVerts.Length) {
            Vector3 pt = m.MultiplyPoint3x4(origVerts[i]);
            pt.y *= stretch;
            newVerts[i] = inv.MultiplyPoint3x4(pt);
            i++;
        }
        mf.mesh.vertices = newVerts;
    }
}
import UnityEngine
import System.Collections

public class ExampleClass(MonoBehaviour):

	public rotAngle as float

	public stretch as float

	private mf as MeshFilter

	private origVerts as (Vector3)

	private newVerts as (Vector3)

	def Start() as void:
		mf = GetComponent[of MeshFilter]()
		origVerts = mf.mesh.vertices
		newVerts = array[of Vector3](origVerts.Length)

	def Update() as void:
		rot as Quaternion = Quaternion.Euler(rotAngle, 0, 0)
		m as Matrix4x4 = Matrix4x4.TRS(Vector3.zero, rot, Vector3.one)
		inv as Matrix4x4 = m.inverse
		i as int = 0
		while i < origVerts.Length:
			pt as Vector3 = m.MultiplyPoint3x4(origVerts[i])
			pt.y *= stretch
			newVerts[i] = inv.MultiplyPoint3x4(pt)
			i++
		mf.mesh.vertices = newVerts