Why is my cube distorting during xyz rotation?

[kored]

My cube has the right proportions when rotated around the x, y, or z axis, exclusively.
However, when I combine the axes, the cube distorts during rotation.

What would cause this?
My code for this rotation, looks like this:

void OpenGLClass::MatrixRotationXYZ(
	float* matrix, const float& angle) {
	matrix[0] = cosf(angle);	matrix[1] = sinf(angle);	matrix[2] = -sinf(angle);	matrix[3] = 0.0f;

	matrix[4] = -sinf(angle);	matrix[5] = cosf(angle);	matrix[6] = -sinf(angle);	matrix[7] = 0.0f;

	matrix[8] = sinf(angle);	matrix[9] = sinf(angle);	matrix[10] = cosf(angle);	matrix[11] = 0.0f;

	matrix[12] = 0.0f;			matrix[13] = 0.0f;			matrix[14] = 0.0f;			matrix[15] = 1.0f;

	return;
}

Might it have anything to do with my PerspectiveFovLHMatrix?

	matrix[0] = 1.0f / (screenAspect * tan(fieldOfView * 0.5f));
	matrix[1] = 0.0f;
	matrix[2] = 0.0f;
	matrix[3] = 0.0f;

	matrix[4] = 0.0f;
	matrix[5] = 1.0f / tan(fieldOfView * 0.5f);
	matrix[6] = 0.0f;
	matrix[7] = 0.0f;

	matrix[8] = 0.0f;
	matrix[9] = 0.0f;
	matrix[10] = screenDepth / (screenDepth - screenNear);
	matrix[11] = 1.0f;

	matrix[12] = 0.0f;
	matrix[13] = 0.0f;
	matrix[14] = (-screenNear * screenDepth) / (screenDepth - screenNear);
	matrix[15] = 0.0f;

Or, something else?

[carsten_neumann]

That does not look like a rotation matrix to me, see e.g. this article.

[kored]

It sure doesn’t.
Someone said to just combine the x, y, and z rotations, so I tried something, without knowing what I was doing.

Your link was very helpful. Especially General 3D Rotations.

I got something.
Only, it’s not exactly the rotation I was looking for, but now I know what I am doing, and the cube maintains proper proportion.

void OpenGLClass::MatrixRotationXYZ(
	float* matrix, const float& angle, const float& angleX, const float& angleY, const float& angleZ) {

	matrix[0] = cosf(angle) * cosf(angle);			
	matrix[1] = cosf(angle) * sinf(angle) * sinf(angle)  - sinf(angle) * cosf(angle);
	matrix[2] = cosf(angle) * sinf(angle) * cosf(angle) + sinf(angle) * sinf(angle);
	matrix[3] = 0.0f;

	matrix[4] = sinf(angle) * cosf(angle);
	matrix[5] = sinf(angle) * sinf(angle) * sinf(angle) + cosf(angle) * cosf(angle);
	matrix[6] = sinf(angle) * sinf(angle) * cosf(angle) - cosf(angle) * sinf(angle);
	matrix[7] = 0.0f;

	matrix[8] = -sinf(angle);
	matrix[9] = cosf(angle) * sinf(angle);
	matrix[10] = cosf(angle) * cosf(angle);
	matrix[11] = 0.0f;

	matrix[12] = 0.0f;			
	matrix[13] = 0.0f;			
	matrix[14] = 0.0f;			
	matrix[15] = 1.0f;

	return;
}

Thanks.

[theRPGmaster]

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