"Stick" rigidbodies to softbody

[josemendez]

Hello.

First of all thanks for that coding tip.

I know I am troubling you a lot, but please I really need help regarding Matrix4x4 you mentioned.

Code:

private void HandleGlitters()
{
if (glittersList.Count <= 0)
return;

for (int i = 0; i < glittersList.Count; i++)
{
Matrix4x4 particlesMatrix = Matrix4x4.TRS(slimeActor.GetParticlePosition(glittersList[i].particleIndex), slimeActor.GetParticleOrientation(glittersList[i].particleIndex), Vector3.one);

glittersList[i].transform.position = MatrixUtils.ExtractPosition(particlesMatrix) - glittersList[i].particleAttachOffset;
glittersList[i].transform.rotation = MatrixUtils.ExtractRotation(particlesMatrix);
}
}

Is this code correct? Because those small spheres are still floating in air.

This is the MatrixUtils class:

Code:

using UnityEngine;

public static class MatrixUtils
{
    public static Quaternion ExtractRotation(this Matrix4x4 matrix)
    {
        Vector3 forward;
        forward.x = matrix.m02;
        forward.y = matrix.m12;
        forward.z = matrix.m22;

        Vector3 upwards;
        upwards.x = matrix.m01;
        upwards.y = matrix.m11;
        upwards.z = matrix.m21;

        return Quaternion.LookRotation(forward, upwards);
    }

    public static Vector3 ExtractPosition(this Matrix4x4 matrix)
    {
        Vector3 position;
        position.x = matrix.m03;
        position.y = matrix.m13;
        position.z = matrix.m23;
        return position;
    }

    public static Vector3 ExtractScale(this Matrix4x4 matrix)
    {
        Vector3 scale;
        scale.x = new Vector4(matrix.m00, matrix.m10, matrix.m20, matrix.m30).magnitude;
        scale.y = new Vector4(matrix.m01, matrix.m11, matrix.m21, matrix.m31).magnitude;
        scale.z = new Vector4(matrix.m02, matrix.m12, matrix.m22, matrix.m32).magnitude;
        return scale;
    }
}

This script does exactly the same as your previous one, but in a more convoluted way: you’re storing the position in a matrix, then immediately extracting and applying it. So the result is the same as before.

Also, you’re applying the particle rotation to your sphere directly, which will make no differente since a sphere rotating around its center looks as if was not rotating at all.

You need to express the position of your sphere in the particle’s local space. Read about local/world space and basis vectors/matrices, this is a fundamental part of making games that you will use very often.

On monday I will write a small sample script for you. cheers!