Disable twosided key for player head to enable shadow volume cast

[mmillar-bolis]

Describe the Bug: The main Doom 3 campaign has a problem when g_showplayershadow is on: the player's head does not cast a shadow. This issue is present in vanilla Doom 3 BFG as well. This can be fixed by changing materials/characters.mtr and commenting out the shader keyword twosided on line 2483:

models/characters/player/playerhead
{
        noselfShadow
    noOverlays
    flesh
    clamp
    //twosided

    renderbump  -size 512 512 -trace 0.07 -colorMap -aa 2  models/characters/player/playerhead_512_local.tga models/characters/player/playerhead_hi.lwo

According to posts online, twosided apparently not only draws a texture on both sides of the mesh, but also disables it's shadow volume cast, leading to the issue we see with the head. Other meshes use this keyword for hair and glasses, but no other part of the player body does. The Resurrection of Evil and Lost Episode player models do not exhibit this issue either.

Screenshots:

Screenshot 1 - Default rendering of player using twosided shader key on head, resulting in headless shadow. ​

Screenshot 2 - Fixed rendering of player by removing twosided shader key from head, resulting in normal shadow. ​

Desktop:

• OS: Windows 10 x64 (21H2)
• GPU: Nvidia GeForce RTX 2060
• Version: Doom BFA 1.3.0 win-x64 Nov 17 2023 19:07:41 (Nightly build 7cadbd0)

[mmillar-bolis]

Excellent, thank you so much!

[MadDeCoDeR]

I just re-run the merge action after I updated the repo with the asset files. Sadly vcpkg decided to re-compile ffmpeg so in an hour from now the new prebuilds should be ready