Quote: "BTW 768x768 textures is possible?"
While technically you could use NPOT textures, the issues really is that due to compatibility issues with graphics drivers and graphic cards power of 2 squared is used. 8, 16, 32, 64, 128, 256, 512, 1024, 2048 and 4096, occasionally you will find 8 k textures in games these days. In fact UDK enforced power of 2 rule for quite some time.
While you could use NPOT textures, some engine have particular strict rules in this regard, and some times won't render the texture at all, as the engine now has to take your NPOT texture and convert and make it power of two to be able to use things like mipmapping, which is use in gameguru especially with DDS textures. This actually entails a performance hit.
While it would make little difference in a small 2D game, the knock on effect in a complex 3D game with lots of detail WILL result in performance degradation. Gameguru classic has its routes in DBO classic which means it isn't as flexible with textures as more modern engine, we are talking about some thing that was created over 15 years ago.So from a performance and compatibility standpoint it is a hard rule for any artist in gameguru while not technically not enforced you will have issues especially with mipmapping, which gameguru uses for pretty much any texture in gameguru from, terrain to decals.
Classic system requirements at the time of release supported older graphics cards and still support older graphics cards.
It is really only after the Nvidia 6X00 series that there was better support for NPOT textures, people using older GPU's which is still very likely in some cases these GPU's may result in Serious performance issues, gameguru crashing and in some cases textures not rendering at all. Opengl 2.0 has support for NPOT textures but gameguru only uses DX rendering pipeline.
So it is a hard rule but not enforced rule for gameguru that textures are required to be power of 2 squared, especially with DDS textures and mipmapping.
Back to why 512 x 512 textures is really bad quality wise.
Entity in gameguru with a 4096 x 4096 texture and a 1080p screen resolution, this is my default screen resolution, the quality of the texture won't improve with a lower screen resolution.
Same entity with a 512 x 512
The difference is day and night.
Textures take up GPU memory, the average size of a 4096x 4096 textures with an alpha channel is 23 odd MB, and if you use and reuse an atlas texture for several different entities it only loads the texture atlas once for all the entities that use the same atlas. Gameguru has been using this method since the start, so it uses very little GPU memory overall. So you can use the same barrel a 1000 times in a level and it will still use the same amount of GPU memory as if you placed one barrel, you will only be limited by the amount of polygons you will be able to render in a scene.
There is a much higher performance penalty using a high polygon model versus a low polygon model with an exceptional higher quality texture.If you use a texture atlas for several different entities you can get away with higher polygon models with min performance hit as you only need to load the textures atlas once.
It is cheaper and far less of a performance hit to make a texture atlas with several different oil barrel textures, then having several barrels each with their own texture as each barrel texture will need to be loaded into the GPU memory at least once, versus the texture atlas which is loaded once for several different barrels.
Max requires 4k textures as a min for VR. As the default min resolution of a VR headset is 1080p, with better VR units supporting 4K resolution. 512 x 512 textures on vast majority of entities simply won't cut it at min you shouldn't be using less then 2k/1k textures for med size objects, with the rare exception of 512 textures for really small entities.
If you look at the cellar demo folder the large objects like ceiling and walls all use 4k textures with the rare exception most entities are 2k and every texture is power of 2 square. 4k textures is pretty standard and default texture size these days, it is pretty rare to see entities below the 1k mark let alone the 4k mark.
It isn't based on opinion having been creating content for TGC products from FPSC classic to X10, gameguru and now max, having released several thousand of models close to 15 years now, pretty well versed in creating content and having released my own model pack on steam via TGC and selling another, it comes down to experience and plenty of trial and error and mistakes, I can confidently tell you a 4k texture would be less of a performance hit rendering 30k polygon models with the same atlas then trying to render several 30k polygon models each with their own texture.Besides GPU memory has increase so drastically over the last few years, 4k textures is barely able to make a dent in GPU memory. Next year should see entry level GPU's with a min of 4gb of memory. It is really much ado about nothing.
Win10 Pro 64bit----iCore5 4590 @ 3.7GHZ----AMD RX460 2gb----16gig ram