microsoft / DirectXMath

DirectXMath is an all inline SIMD C++ linear algebra library for use in games and graphics apps

https://walbourn.github.io/introducing-directxmath/

Comment does not match with actual code?

zznewclear13 opened this issue 2 years ago · comments

zznewclear13 commented 2 years ago

Our left handed perspective matrix should be like this:

$\begin{bmatrix}\frac{1}{tan(\frac{fovy}{2}) \cdot \frac{x}{y}} & 0 & 0 & 0 \\0 & \frac{1}{tan(\frac{fovy}{2})} & 0 & 0 \\0 & 0 & \frac{far}{far - near} & 1 \\0 & 0 & -\frac{far \cdot near}{far - near} & 0 \\\end{bmatrix}$

But the comments in DirectXMathMatrix.inl#L2518-L2521 seem to indicate the projection matrix is:

$\begin{bmatrix}\frac{1}{tan(\frac{fovy}{2})} & 0 & 0 & 0 \\0 & \frac{1}{tan(\frac{fovy}{2}) \cdot \frac{x}{y}} & 0 & 0 \\0 & 0 & \frac{far}{far - near} & 1 \\0 & 0 & -\frac{far \cdot near}{far - near} & 0 \\\end{bmatrix}$

Chuck Walbourn commented 2 years ago

The comments do look a little out of place...

Chuck Walbourn commented 2 years ago

Fixed 0fc79cd