public FMatrix ToMatrixWithScale()
{
var outMatrix = new FMatrix();
outMatrix.M30 = Translation.X;
outMatrix.M31 = Translation.Y;
outMatrix.M32 = Translation.Z;
var x2 = Rotation.X + Rotation.X;
var y2 = Rotation.Y + Rotation.Y;
var z2 = Rotation.Z + Rotation.Z;
{
var xx2 = Rotation.X * x2;
var yy2 = Rotation.Y * y2;
var zz2 = Rotation.Z * z2;
outMatrix.M00 = (1.0f - (yy2 + zz2)) * Scale3D.X;
outMatrix.M11 = (1.0f - (xx2 + zz2)) * Scale3D.Y;
outMatrix.M22 = (1.0f - (xx2 + yy2)) * Scale3D.Z;
}
{
var yz2 = Rotation.Y * z2;
var wx2 = Rotation.W * x2;
outMatrix.M21 = (yz2 - wx2) * Scale3D.Z;
outMatrix.M12 = (yz2 + wx2) * Scale3D.Y;
}
{
var xy2 = Rotation.X * y2;
var wz2 = Rotation.W * z2;
outMatrix.M10 = (xy2 - wz2) * Scale3D.Y;
outMatrix.M01 = (xy2 + wz2) * Scale3D.X;
}
{
var xz2 = Rotation.X * z2;
var wy2 = Rotation.W * y2;
outMatrix.M20 = (xz2 + wy2) * Scale3D.Z;
outMatrix.M02 = (xz2 - wy2) * Scale3D.X;
}
outMatrix.M03 = 0.0f;
outMatrix.M13 = 0.0f;
outMatrix.M23 = 0.0f;
outMatrix.M33 = 1.0f;
return(outMatrix);
}
public static FMatrix operator *(FMatrix a, FMatrix b)
{
var result = new FMatrix
{
M00 = a.M00 * b.M00 + a.M01 * b.M10 + a.M02 * b.M20 + a.M03 * b.M30,
M01 = a.M00 * b.M01 + a.M01 * b.M11 + a.M02 * b.M21 + a.M03 * b.M31,
M02 = a.M00 * b.M02 + a.M01 * b.M12 + a.M02 * b.M22 + a.M03 * b.M32,
M03 = a.M00 * b.M03 + a.M01 * b.M13 + a.M02 * b.M23 + a.M03 * b.M33,
M10 = a.M10 * b.M00 + a.M11 * b.M10 + a.M12 * b.M20 + a.M13 * b.M30,
M11 = a.M10 * b.M01 + a.M11 * b.M11 + a.M12 * b.M21 + a.M13 * b.M31,
M12 = a.M10 * b.M02 + a.M11 * b.M12 + a.M12 * b.M22 + a.M13 * b.M32,
M13 = a.M10 * b.M03 + a.M11 * b.M13 + a.M12 * b.M23 + a.M13 * b.M33,
M20 = a.M20 * b.M00 + a.M21 * b.M10 + a.M22 * b.M20 + a.M23 * b.M30,
M21 = a.M20 * b.M01 + a.M21 * b.M11 + a.M22 * b.M21 + a.M23 * b.M31,
M22 = a.M20 * b.M02 + a.M21 * b.M12 + a.M22 * b.M22 + a.M23 * b.M32,
M23 = a.M20 * b.M03 + a.M21 * b.M13 + a.M22 * b.M23 + a.M23 * b.M33,
M30 = a.M30 * b.M00 + a.M31 * b.M10 + a.M32 * b.M20 + a.M33 * b.M30,
M31 = a.M30 * b.M01 + a.M31 * b.M11 + a.M32 * b.M21 + a.M33 * b.M31,
M32 = a.M30 * b.M02 + a.M31 * b.M12 + a.M32 * b.M22 + a.M33 * b.M32,
M33 = a.M30 * b.M03 + a.M31 * b.M13 + a.M32 * b.M23 + a.M33 * b.M33
};
return(result);
}
public static void ConstructTransformFromMatrixWithDesiredScale(FMatrix aMatrix, FMatrix bMatrix, FVector desiredScale, ref FTransform outTransform)
{
// the goal of using M is to get the correct orientation
// but for translation, we still need scale
var m = aMatrix * bMatrix;
m.RemoveScaling();
// apply negative scale back to axes
var signedScale = desiredScale.GetSignVector();
m.SetAxis(0, signedScale.X * m.GetScaledAxis(EAxis.X));
m.SetAxis(1, signedScale.Y * m.GetScaledAxis(EAxis.Y));
m.SetAxis(2, signedScale.Z * m.GetScaledAxis(EAxis.Z));
// @note: if you have negative with 0 scale, this will return rotation that is identity
// since matrix loses that axes
var rotation = new FQuat(m);
rotation.Normalize();
// set values back to output
outTransform.Scale3D = desiredScale;
outTransform.Rotation = rotation;
// technically I could calculate this using FTransform but then it does more quat multiplication
// instead of using Scale in matrix multiplication
// it's a question of between RemoveScaling vs using FTransform to move translation
outTransform.Translation = m.GetOrigin();
}