Zaphero: Looking into it people say that Glide has additional light sources and effects over Direct3D for this game, but unfortunately the comparison image links for the old GOG discussion are dead and... I just don't see any difference other than occasional changes in brightness that you can adjust back from the video menu. In fact, Glide seems to be worse with how it handles shadows, cutting off shadows within a certain radius and (according to pcgamingwiki) framerates where Direct3D supports framerates at 120 and above, Glide only supports up to 62.5.

(Note: Time gap between screenshots; Direct3D was taken before the Howler started bleeding out. Images attached if links don't embed)
Direct3D:
https://steamuserimages-a.akamaihd.net/ugc/1012690533788334870/6C3354A7E0A0C72972D34AE1D36C71B953A06382/
Glide:
https://steamuserimages-a.akamaihd.net/ugc/101269000533788335762/C78E5621D3F24627DC4323FB9A91D9C9EA4D8798/

For reference I'm using the 1.12 widescreen and high resolution patch (which gives Glide 32bit texture support to match Direct3D along with the obvious) as well as running both through dgvoodoo 2.63 installed over it, but that shadow cut off has been a problem with everything I've played this game through glide with.
https://www.moddb.com/mods/widescreen-high-resolutions

Am I missing something here?