I have been using C#'s Matrix4x4 class, and I'm getting a bit confused.
In the public fields of the Matrix4x4 class, it clearly shows the definitions of all of its properties here:
#region Public Fields
/// <summary>
/// Value at row 1, column 1 of the matrix.
/// </summary>
public float M11;
/// <summary>
/// Value at row 1, column 2 of the matrix.
/// </summary>
public float M12;
/// <summary>
/// Value at row 1, column 3 of the matrix.
/// </summary>
public float M13;
/// <summary>
/// Value at row 1, column 4 of the matrix.
/// </summary>
public float M14;
/// <summary>
/// Value at row 2, column 1 of the matrix.
/// </summary>
public float M21;
/// <summary>
/// Value at row 2, column 2 of the matrix.
/// </summary>
public float M22;
But when examining it's CreateRotationX function:
public static Matrix4x4 CreateRotationX(float radians)
{
Matrix4x4 result;
float c = (float)Math.Cos(radians);
float s = (float)Math.Sin(radians);
// [ 1 0 0 0 ]
// [ 0 c s 0 ]
// [ 0 -s c 0 ]
// [ 0 0 0 1 ]
result.M11 = 1.0f;
result.M12 = 0.0f;
result.M13 = 0.0f;
result.M14 = 0.0f;
result.M21 = 0.0f;
result.M22 = c;
result.M23 = s;
result.M24 = 0.0f;
result.M31 = 0.0f;
result.M32 = -s;
result.M33 = c;
result.M34 = 0.0f;
result.M41 = 0.0f;
result.M42 = 0.0f;
result.M43 = 0.0f;
result.M44 = 1.0f;
return result;
}
It transposes the values of result.M23 and result.M32.
Sure, the internal structure of how it represents it self can be in Row major or in Column major.
But then what I don't understand is when I do this:
var matrix = CreateRotationZ(90 * 3.1415926535 / 180.0f) * CreateRotationX(94.84741 * 3.1415926535 / 180.0f)
The resulting multiplication gives me an incorrect answer:
0.0000 -0.0845 0.9964 0.0000
-1.0000 0.0000 0.0000 0.0000
0.0000 -0.9964 -0.0845 0.0000
0.0000 0.0000 0.0000 1.0000
with correct answer being (found by computing via Wolfram Alpha calculator):
0.0000 0.0845 0.9964 0.0000
1.0000 0.0000 0.0000 0.0000
0.0000 0.9964 -0.0845 0.0000
0.0000 0.0000 0.0000 1.0000
What's going on here? I'm sure it can't be a bug in C# Matrix4x4 and I am just perhaps using multiplication incorrectly?