Strange lighting effect

Killtoy · April 2002

<div class="IPBDescription">I've never seen this before...</div>I just noticed this today, so I don't know how long it has been rendering this way. You can see a distinct prismatic pattern on the side of the thruster engine. For those of you not familiar with it, the texture is white.

Also, there is only one color of light used in this room, and only two lights can possibly shine on this face. What do you guys think?

I'm not going to try to fix it, but I'd like to understand it. Right now I'm at a loss.

Killtoy · April 2002

Oops, I forgot to attach the pic... heh.

realityisdead · April 2002

I'm having that happen a lot in my level. I think it's what happens when the engine has to very faintly light a surface. It's apparently not all that precise.

Freestyler · April 2002

Ohh.. whatever it is, it looks neat <img src="http://www.natural-selection.org/iB_html/non-cgi/emoticons/smile.gif" border="0" valign="absmiddle" alt=':)'>

DruBo · April 2002

it's rendering that way ingame as well as in a screenshot, so that rules out game graphics settings... I can see it as well, so that rules out monitor problems or display settings on your end. White light is made up of all the colors of the rainbow, but that shouldn't make them visible.

hmm. let me think about this for a while.

realityisdead · April 2002

DB, I'm almost positive that it is what happens when there is just a faint layer of lighting on a surface. Especially white or grey. I get that all over my walls if I have too many spot lights in one area. They bounce off the walls just enough to VERY faintly light the adjacent wall. The engine is obviously not capable of rendering such fine... light.

Creme · April 2002

Not using any Radiosity or Texture lighting in this scene? Perhaps your video card is rendering it incorrectly at dim light levels.

What 3D graphics accelerator card do you have there? (chipset/board)

Yamazaki · April 2002

You might want to check the texture itself, if it's dithered in a non-monochrome manner then that might be what's causing the effect.

Or you could try bumping your colours up to 32bit and see if it's just a 16bit colour issue.

Trane · April 2002

It sounds like ken is on the ball here, most likely its some glitch in the engine's lighting capablility. I bet if Flayra had a look at the code involved in the lighting he could give us an answer.

realityisdead · April 2002

Though now I'm wondering if it is, in fact, a <b>combination</b> of running on 16Bit color <u>and</u> having a lightcolored wall lit with very indirect faint white light.

Because the thing is: After just looking, I can't find it anymore in my level... and I'm running 32Bit right now. Back when I first noticed it I was most likely running it in 16bit.

Black_Wolf · April 2002

mmmmmmm, its prolly a 16 bit thingy then . . .

Killtoy · April 2002

I'm using a GeForce 2 GTS, and I am running 32-bit color. The texture is a default halflife texture. I'm not really inclined to think that the color deapth on my machine is the problem. This is good motive for me to get the nVidia drivers. <img src="http://www.natural-selection.org/iB_html/non-cgi/emoticons/wink.gif" border="0" valign="absmiddle" alt=';)'>

Black_Wolf · April 2002

naaaah, this just happens, it happens to me as well, a rippling type effect of colours, sometimes on entire hallways . . . and i have a GeFroce 2 GTS Deluxe using the latest nVidia drivers.

badmofo · April 2002

i'm surprised none of you got it...this lighting effect is the true beauty of the HL engine that no other engine to this date really utilizes...true light radiosity. When the lighting is making it's calculations it picks up some of the color from whatever texture it bounces off of and plants that color onto the next texture it hits...that's what you're obvserving...bounced light.

realityisdead · April 2002

Like I said. <b>Indirect</b>, faint light. Bounced in other words.

...

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td><b>Quote</b> </td></tr><tr><td id="QUOTE">I get that all over my walls if I have too many spot lights in one area. They bounce off the walls just enough to VERY faintly light the adjacent wall.</td></tr></table><span id='postcolor'>

Killtoy · April 2002

What I was looking for was a fairly technical explanation for what caused the light to refract into it's seperate simulated wavelengths. I understand HL makes use of radiosity. I guess what I'm curious about is if the light (in Half-Life) refracts differently, dependent on the color.

I would think that this observed effect would confirm that suspicion, but I still wanted to run it past some of the more intelligent members here. My mind tends to melt as I approach the problem of how a computer simulates the wave properties of light.

I'm inclined to agree with Ken at this point, that it is related to dim lighting. I just thought it would be cool to know why...

Black_Wolf · April 2002

i -think- it takes light from the textures it vounces from and slightly colourises the light beams. bounced light (as mofo said)

realityisdead · April 2002

*nods*

If "bouncing" picks up colors off of textures, then it further supports what I'm trying to get across:

This combination of colors is only visible when it just graces a texture. "Bounced" onto the surface <i>just</i> enough to do some substantial coloration, yet maintaining a brightness level low enough to actually allow this to show up. It is my understanding that it only happens when pretty much the only light on a texture is "bounced" light. For the most part anyways.

So... in other words: <b>Indirect, faint, light</b> (on a light colored wall.)

Indirect: Bounced (like I mentioned quite a few posts back, actually...)

Faint: Just enough light so that the surface is barely lit, yet still allows the bounced colors to show up. Any brighter and the pure light would wash out the coloration.

Light colored walls: My reasoning here is that it simply wouldn't be possible to see the rainbow of colors on a dark wall. Though this is just a guess, really. I've only seen it on light surfaces. Not necessarily white, but light regardless.

I also need to further stress that it is (from what I've seen) only happening in dim lit situations. Why? Because it only happens when the main source of light on the surface is bounced light. (again, at least for the most part) Thus the coloration, considering (like bm said) how the bounce process picks up colors off the textures apparently.

That's all I know on the subject, really. And further arguing my point will only be... er... redundant and/or pointless. Hope I'm making sense with this.

So... yeah. <img src="http://www.natural-selection.org/iB_html/non-cgi/emoticons/smile.gif" border="0" valign="absmiddle" alt=':)'>

Strange lighting effect

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