Pixels, Vectors, Collision, and Confusion

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Crelus

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Joined: 9th Jun 2003

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Posted: 1st Feb 2005 00:11

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Hi,

This might have been answered already, but I haven't been able to find a reference to my question so here goes:

Suppose you have your standard 3D game, maybe an RPG, with a screen resolution of 800x600. Now, I click the mouse on the screen at pixel 200,200. From here I need to figure out which, if any, of the moveable/reachable locations have been clicked and what the world coordinate of the intersection is.

I'm thinking this would involve something like this:

1: Create a plane that has the same orintation as the cameras view port.

2: Convert the 2D pixel coordinates into a set of world coordinates on the plane.

3: Case a perpendicular(sp?) ray from the point on the 2D plane. (Is this a normal or something like that?)

4: Using something like nuclear glory (which I have) I'd test to see if the ray hits a floor surface. If it does I'd figure out which one.

5: From there I'd figure out the exact world coordinate of the intersection.

6: I'd calculate a path and start moving my "avatar" towards that spot.

Am I making this more difficult? Is there an easier way or am I totally off track here? What I'm looking for is something like the way that Bioware's Never Winter Nights works with regards to movement.

Any help would be appreciated.
Thanks

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Zokomoko

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Joined: 23rd Nov 2002

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Posted: 1st Feb 2005 00:56

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An easier solution to your situation would be to use a 3d mouse.
Basically, you place a dummy object like a cube, and transfer the mouse 2d coordinates to 3d coordinates, and then place the cube at that location.

I think there may be some snippets about this.

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Nicholas Thompson

20

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Joined: 6th Sep 2004

Location: Bognor Regis, UK

Posted: 1st Feb 2005 00:59

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or pick object..

I think its:
pick object(x, y, start, end)

where x and y are screen coord (from mousex() and mousey()) and start and end are object numbers in the range (ed start testing for objects at 10 and end at 20, etc (NOT DISTANCE.. I made that mistake

)

Any help?

My Website:

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IanG

20

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Joined: 25th Sep 2004

Location: Cyberspace

Posted: 1st Feb 2005 01:12

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pick object if i remeber correctly is very slow

Used to be Phoenix_insane registered in september 2003 despite what the date says to the left <--
PC - amd athlon 2.0ghz, 512mb, GeForce FX 5200 128mb, 200gb, xp pro sp2

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RiiDii

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Joined: 20th Jan 2005

Location: Inatincan

Posted: 1st Feb 2005 02:01

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Pick object works fine if you limit the number of object being tested for to only a few, or one. I like Zokomoko's suggestion personally...

Quote: "An easier solution to your situation would be to use a 3d mouse."