Comments on: Software vs GLQuake: Texture filtering

By: Bad Sector

Bad Sector — Sun, 28 Jun 2009 05:15:35 +0000

Another minor difference is that software quake doesn’t use perspective correct texture mapping for 3D models, making model textures “wave” a bit depending on the viewing angle.

Also i think that for small on-screen triangles another rasterizer is used that basically draws a blob of pixels approximating the triangle instead of performing a full triangle rasterization. This has the side effect that some small objects or object far away appear to stand out more in the software renderer than the OpenGL renderer.

By: Spirit

Spirit — Thu, 25 Jun 2009 18:15:18 +0000

Thanks again for these explanations, metl.

Particles, waterwarp and transparent liquids are things for later chapters. I don’t think that I will go into third-party features.

By: metlslime

metlslime — Tue, 23 Jun 2009 00:00:47 +0000

I just wanted to point out, software quake can’t be perfectly emulated with any of these. The closest you can get is GL_NEAREST_MIPMAP_NEAREST (or perhaps GL_NEAREST) with anisotropic filtering turned up as high as possible.

The main reason is, opengl determines which mipmap level to use based on distance and surface angle, so that sharper angles (floors in the distance) get a smaller mipmap than surfaces perpendicular to the camera (wall facing you at a distance.) The software renderer will choose only based on distance, and doesn’t look at the angle. This means that walls facing you will be similar in both renderers, but floors will be noisy in software quake and blurry in glquake. Anisotropic filtering helps sharpen those angled surfaces, such as floors, which are too blurry when using opengl mipmapping.

The other, more minor difference is that software quake only uses 4 mipmap levels, so anything super far away will get noisy because it has no smaller images to mip down to. Opengl generates mipmaps all the way down to a 1×1 image.

By: gb

gb — Mon, 22 Jun 2009 20:54:37 +0000

and also, transparency, which is apparently impossible in software Quake >:-( (Quake 2 and Hexen 2 do it, though)

By: gb

gb — Mon, 22 Jun 2009 20:47:58 +0000

I like the antialiased edges in GLquake. The better looking decals, logos, and things like skyboxes, fog and colored lighting.

I don’t like its weird flat lighting, the fact that it makes flames, torches and candles look bad (do a comparison, I suggest playing coag3_gb in software for once to see the intended lighting), and the fact that it smears the floor textures in front of me :-(

Also, there’s no waterwarp in GLquake…

GLquake can in some cases even make walls have entirely different colors than in software. Mostly textures that are only dimly lit.

I have said this elsewhere, but I’ll repeat it here: The idea to remove the software renderer from engines, “because it’s 1999, man!1!”, seems really dated today. Software rendering is not per se worse than GL.

Oh if we only had one engine to worry about…

By: onetruepurple

onetruepurple — Mon, 22 Jun 2009 20:11:48 +0000

You may also want to add cvars for how particles look – so you can alternate between nearest + pixels and linear + dots.

In fitz, that’s r_particles 1 and 2. No idea about others..

By: deus

deus — Mon, 22 Jun 2009 17:09:28 +0000

nice observation and well presented.