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DarkBASIC Professional Discussion / Black light produces weird result

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Philip
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Posted: 10th Nov 2003 16:43
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Now this is something I genuinely fail to understand.

Regular readers will recall I recently posted on the subject of shadows and shadow shading. After posting that thread, I encountered a thread in the Dark Basic forum in which someone spoke of using a light with the colour black to cast a fake shadow. So I thought I'd give it a go. See attached code.

The weird thing is that having created light 1 I see it actually BRIGHTENS the other half of the sphere (the half towards the gold box). Surely this is irrational? A black light should by definition make things darker, or at least, not any lighter.

Could this be a bug? Thoughts?

Philip

What do you mean, bears aren't supposed to wear hats and a tie?
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heartbone
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Posted: 10th Nov 2003 16:50 Edited at: 10th Nov 2003 16:50
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Actually black light would make it brighter if the sphere has a phosphorescent or florescent coating.

I think that DB objects exhibit florescence.

The more you see, the more you know.
The more you know, the more you see.
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Philip
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Posted: 10th Nov 2003 16:57
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Right. Ok. How do I make it *darker*???

Ta

Philip

What do you mean, bears aren't supposed to wear hats and a tie?
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Scraggle
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Posted: 10th Nov 2003 20:09
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Kick me if I'm wrong but I believe that SET OBJECT AMBIENCE will do the trick.

My latest project has no name - feel free to suggest one. Think 'Lunar Lander' with multiplayer, guns and bombs!

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AlecM
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Posted: 11th Nov 2003 03:48
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A black light (as in a light at 0,0,0) Won't affect anything. Thats like saying you want to shine nothing on something. I have never tested this in DBP but in any render engine or other enviroment I have seen a light with no value does nothing. If you want a light to suck up other light try a negative light source. I don't think this is possible in DB though.

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Xander
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Posted: 11th Nov 2003 05:49
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YES! A negative light source is possible. An example comes with DB.

Set the light color to rgb(-255,-255,-255)

Xander - Bolt Software

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Philip
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Posted: 11th Nov 2003 15:43
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Ok. Things have now gotten weirder.

In the attached code I've tried to make a spot light that shines the negative light rgb(-255, -255, -255) at the yellow box. Yet, despite that it is supposedly pointing at the yellow screen, it actually lights up the reverse side of the sphere, which is on the opposite side to the angle the spot is pointing.

Even stranger, if I turn the spot into a point light, it still lights up the closest side of the sphere, just like the code posted above.

Am I missing something fundamental here???

Cheers

Philip

What do you mean, bears aren't supposed to wear hats and a tie?
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Philip
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Posted: 11th Nov 2003 15:44
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PS: I thought I'd try shining a brown light on the yellow box - rgb(128, 042, 042) - but that had no effect at all.

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