DescentBB

Something that might be an interesting graphics addition for D2X would be emissive mapping, as used in some of the later Unreal engines. What emissive mapping does is create a \"glow\" around the material. It doesn't actually produce light, but the material has the illusion of being blindingly bright.

This may not be common terminology as I could find very little on the subject.

It seems to add a lot to Unreal 3 worlds, however. It can be used for lights, laser beams, and other things that would plausibly create light.

Doom 3 / Quake 4 calls these texture layers glow maps, because that's what they do: glow in the dark.

In this pic:

http://pnmedia.gamespy.com/planetcnc.ga ... t00010.jpg

Observe how you can see the red and yellow \"lights\" on the spider cyborg thing, even though the model itself is in the shadow. Those \"lights\" are painted-on with a glowmap layer. A glowmap layer was also used for the far back wall texture, notice how you can see faint amber lights on the wall even though you can hardly see the wall (the blue lights on the left, however, are actually lightmaps plus [probably] a glowmap effect).

One use for this technique in Descent would be to make the red scrolling lines on some of the animated wall textures (e.g., reactor area textures) actually visible even in complete darkness. They wouldn't cast light on surrounding surfaces, but you'd be able to see the lines, which makes for a nice creepy effect.

Uhm... I don't think that's quite what he's talking about somehow.

The effect is something closer to the blue tubes toward the back of the room - you'll notice they have a -bit- of a \"halo\" around them (left side of the left one, anyway), which slightly obscures what would normally be behind them.

This most makes sense with extremely bright stuff, though. Similar in concept to the point-your-screen-at-a-sun implementation in Freespace 1/2 - you just couldn't see anything when you did it.

Likewise, trying to see something nearly directly behind a light bulb can be pretty tricky because the halo tends to obscure stuff.

You're actually pointing out two different effects, but I think you're trying to describe what's called bloom. That's when bright surfaces \"leak\" or \"spill\" light, creating a pseudo-rendering of what it feels like to look at something bright - it obscures the dark things.

The blue glow around the tubes in the Quake 4 shot I presented is not bloom but merely a simple particle effect, a fact that is plain to see if you look at the space above the foreground blue tubes; the fog particles are pretty distinctive.

I'm still pretty sure U3 calls glowmaps emissive mapping, though. Look at this post from GameDev discussing a shot from Unreal3:

http://www.gamedev.net/community/forums ... _id=364875

The effect being talked about is that the red chevrons and blue lines are evenly and brightly lit even though the cube itself is unevenly and relatively darkly lit. In other words, the chevrons/lines are emitting their own light based on a special texture map that indicates what colour they emit - an emissive map. Or, to Doom3/Quake4, a glowmap.

Bloom is this:

http://www2.fileplanet.com/images/15000 ... ss_sm2.jpg

Notice how the light source - the fluorescent tubes - has spilled over its light to the surrounding screen area instead of just the surrounding surfaces. That's bloom.

Right...

Although the glow maps aren't perfectly realistic - if it's emitting light, it's always casting on something - they are a reasonable approximation of low-powered lights like LEDs, which are gloriously ineffective for lighting up anything other than themselves.

I don't know whether this would make any sense in D2, as all D2 textures that would be candidates for such a treatment cast light and hence are bright anyway ... or am I wrong? I just can't think of a texture that doesn't right now.

I guess the way that it'd work is that you'd change the textures so that instead of casting light (or as much light), they had a strong glowmap instead. This gives the area an \"eerie\" effect when players can see, for example, the alien LCD screen flashing gobbledygook on the wall on the far side of the room - but not the walls themselves!

It would also be useful for the robots' eyes; those would be the only elements of the 'bots that would stand out in the darkness.

Unreal Engine 3 calls it the Emissive in the Materials Editor. But it's really a blooming effect that allows materials that use it to appear constantly bright, no matter what's around them. So, robot eyes would glow in the dark. In UE3, this can be set by a texture or a Constant. Constants = 1 produce glows like you see on the spider's legs there. Constants > 1 produce very bright emissive effects - sort of like when you look at street lamps in the darkness.

How it could work in Descent is that a pixel color in a texture could be assigned as \"emissive.\" On a per-texture basis, wherever that color appears, it is rendered as emissive. Another parameter could be emission strength. The texture could still cast light per the normal settings - but now it appears blinding if you actually stare at it.

What it would do is create a very strong contrast between the light areas in Descent and the dark areas.

It's a random thought. Between Unreal Tournament 2004 and the new engine, this and the addition of HDR are the biggest visual differences. HDR, as we should know, is the \"overbrightening\" effect, similar to when you look at a building the sun is shining on. Instead of rendering the textures as \"fullbright,\" they appear to glow blindingly. The sterile blue corridors in HL2 Ep1's Citadel use this effect a lot.