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Geek Culture / Nuclear Glory - Final, prepurchase question ...

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Fallout
22
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Joined: 1st Sep 2002
Location: Basingstoke, England
Posted: 17th May 2004 18:37
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First up, the reason why its here is because I thought other people might like to know the answer.

When NG returns the normals of a position of collision, how is it calculated? I'm going to need to make bouncing collision, so the normals will be important, so are they derived from normals stored within mesh data, or are they calculated within NG?

I don't even need NG collisionpro right now, but seeing as its such damn good value for money, I thought I might aswell buy the bastard anyway! Just need to make sure the normals returned are derived from some sorta maths, as I'll be bouncing on home made meshes that DO NOT have the lighting normals for vertices set properly, so as stupid as it sounds, just double checking it doesnt use the normals stored for vertices to calculate collision normals.

Signature? No! Obsolete! These days it's all about chip and pin!
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dark coder
21
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Joined: 6th Oct 2002
Location: Japan
Posted: 17th May 2004 18:53
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download the demo and try it out,

they are calculated in the collision system after you cast a ray

just use the command RayHitNormPRO for the x y and z agles, they are then returned as vectora and use the vector to yaw/pitch then assign thos angles yo your object and your set

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nuclear glory
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Joined: 2nd Oct 2003
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Posted: 18th May 2004 06:51 Edited at: 18th May 2004 06:53
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The DLL calculates all of it's own normals.

When normals are returned, their values will differ between ellipsoid and ray-cast collision.

Ellipsoid collision:
The normal is calculated at the contact point where the ellip meets the mesh. The normal points towards the center of the ellip from the contact point. So... if an ellip is squarely hitting a triangle, the normal returned will be the same as the triangle normal. If you're hitting an edge or vertex, the normal will change as you slide over it (because it's re-adjusting to point towards the center of the ellip). This, in fact, should be perfect for making things bounce around in a level.

Ray cast:
A ray doesn't have volume, so when it hits a mesh it ALWAYS squarely meets a triangle face. A normal returned from a ray-cast hit will always be the same as the triangle normal.

Hope that clears the fog.

Lead Programmer/Director
Powerful Collision DLL for DBPro and DBC: http://www.nuclearglory.com
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Fallout
22
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Joined: 1st Sep 2002
Location: Basingstoke, England
Posted: 18th May 2004 14:21
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Just want I wanted to hear mate, but I'm afraid you're too late. I've already given you my money! Picked it up last night. I mean, it's great value - literally I'd burn £10 on a pack of cigarettes and a couple of beers, so I can't complain. Just have to wait to the end of my exams and start giving it a whirl.

Thanks for the help though. That does sound very handy. I didnt realise normals would be returned that differ from the normal of the polygon face. As you said, that's spot on for bouncing collision. I'm looking forward to winging grenades off the corners of walls in the near future.

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nuclear glory
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Posted: 18th May 2004 20:23
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Haha

If you ever finish anything, feel free to drop it by our showcase or forums. We always have room for grenade winging.

Lead Programmer/Director
Powerful Collision DLL for DBPro and DBC: http://www.nuclearglory.com
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Fallout
22
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Joined: 1st Sep 2002
Location: Basingstoke, England
Posted: 18th May 2004 22:42
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No probs. I know everybody loves a bit of grenade winging. I'll be sure to let you know.

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