Help needed with a transform hierarchy system

[Boyfinn]

I've been trying to implement a transform hierarchy system. So far I've only managed to copy the exact transform of an object's parent and applying it to a child of the same type.
All my objects (with and without meshes) have a Transform member. So far I've used the Transform type from raylib, used in skeletal and vertex transformations internally by raylib.
I've also tried implementing my own Transform type, with a pointer to the transform's parent, according to this:
https://gabormakesgames.com/transforms.html
My first attempt was turning a Transform into a 4x4 transformation Matrix like this:

Matrix MatrixFromTransform(const T3D& Trs)
{
	//Matrix translation
	Matrix _tfMatrix = MatrixIdentity();

	//Matrix scale (in local space)
	Matrix _scMatrix = MatrixScale(Trs.Scale.x, Trs.Scale.y, Trs.Scale.z);
	_tfMatrix = MatrixMultiply(_tfMatrix, _scMatrix);	//applyScale

	//Matrix rotation
	Matrix _rtMatrix = QuaternionToMatrix(Trs.Rotation);	//Convert Quaternion to rotation matrix

	Matrix _trMatrix = MatrixIdentity();	//translationMatrix
	if (Trs.Position.x != 0 || Trs.Position.y != 0 || Trs.Position.z != 0)
		_trMatrix = MatrixTranslate(Trs.Position.x, Trs.Position.y, Trs.Position.z);

	//Finalize transform
	_tfMatrix = MatrixMultiply(_tfMatrix, _rtMatrix);	//applyRotation
	_tfMatrix = MatrixMultiply(_tfMatrix, _trMatrix);	//applyTransform

	//this->_model.transform = _tfMatrix;
	return _tfMatrix;
}

Note that T3D here is the custom transform type with a pointer to It's parent. It's implemented pretty much identically to it's counterpart over in the blog I've linked. But just for clarity, here is what it looks like:

struct T3D
{
	Vector3 Position = { 0,0,0 };
	Quaternion Rotation = {0,0,0,1};
	Vector3 Scale = {1,1,1};
	T3D* Parent = nullptr;
};

And here is my slightly modified implementation of GetWorldMatrix() from the blog:

Matrix GetWorldMatrix(const T3D& Trs) {
	Matrix localMatrix = MatrixFromTransform(Trs);
	Matrix worldMatrix = localMatrix;

	if (Trs.Parent != nullptr) {
		Matrix parentMatrix = GetWorldMatrix(*Trs.Parent);
		worldMatrix = MatrixMultiply(localMatrix , parentMatrix);
	}
	return worldMatrix;
}

For every Update() call in my object tree, I call this function as such:
this->_transform = TransformFromMatrix(GetWorldMatrix(this->_transform));
And whenever I apply this to a 3D model, i Just update the Model transform by turning it into a matrix with the MatrixFromTransform() function mentioned earlier.

The issue I'm having, is that all the children of an object just inherit the root object's transform directly when calling the GetWorldMatrix() function in this manner.
And in addition, If i try to add rotation to the transform IE: anything else than Quaternion.identity, All the objects and models just explode and fly off the screen during the first frame.
I've also tried using the blog's example of a Transform-Matrix function, but I'm not sure the order given within the blog's example applies here:

Matrix MatrixFromTransform(const T3D& Trs) {
	// First, extract the rotation basis of the transform
	Vector3 x = Vector3RotateByQuaternion(Vector3{ 1,0,0 }, Trs.Rotation);
	Vector3 y = Vector3RotateByQuaternion(Vector3{ 0,1,0 }, Trs.Rotation);
	Vector3 z = Vector3RotateByQuaternion(Vector3{ 0,0,1 }, Trs.Rotation);

	// Next, scale the basis vectors
	x = Vector3Scale(x , Trs.Scale.x); // Vector * float
	y = Vector3Scale(y , Trs.Scale.y); // Vector * float
	z = Vector3Scale(z , Trs.Scale.z); // Vector * float

	// Extract the position of the transform
	Vector3 t = Trs.Position;

	// Create matrix
	return Matrix{
		x.x, y.x, z.x, t.x,
		x.y, y.y, z.y, t.y,
		x.z, y.z, z.z, t.z,
		0, 0, 0, 1
	};
}

Otherwise, the first implementation of MatrixFromTransform() shown earlier, works fine for objects with no children.

I'd greatly appreciate if anyone here with better understanding of 3D transformations could help me out here.
I can provide more code/snippets if anyone needs it. Just let me know.

Thank you.

[Boyfinn]

I've completely neglected my global transform for each object. Closing this thread, sorry for the confusion

[coderextreme]

Hi, I’ve been thinking about implementing my own transform hierarchy. Is there any chance of getting this into Raylib?

[Boyfinn]

https://github.com/juniper-dusk/raylib-transform
Though I'd really appreciate if this feature was added to Raylib. Also, a DrawModel function that implements quaternions as their rotation, which could be useful for teaching purposes too.