Hi, i have 2 questions on this: 1. I now know how to get the plane equation for a triangle (a,b,c and d) but for collision detection you need the plane origin, how do i get this plane origin, like this: vertex(a*d,b*d,c*d); ? 2. Does anyone know any good tutorials on plane equations and collision detection that are not using too much mathemetical notations (i don''t understand them). Thanks

2) Try this: http://www.fluidstudios.com/publications.html : "Generic Collision Detection for Games Using Ellipsoids"


You should never let your fears become the boundaries of your dreams.

_DarkWIng_: You could at least point to the local version of that document

Enigma

Thanks, i will look into that now.
One question though, i found out this a while ago:

Lets say you have found the point on the plane where a ray collides with it, and you get the normals from the vertices (of the triangle) to the collision point. Then you make a normal by summing the 3 normals. If the size of that normal is larger than 1.0, the point is outside the triangle.

Is this correct?

Thanks

quote:

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Original post by Enigma
_DarkWIng_: You could at least point to the local version of that document
Enigma

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I would, but the verison on gamedev is outdated. The new verison (my link ) has fixed some bugs and has some parts explained a bit better.

@Tree Penguin: There are number of ways to calculate if point is in triangle or not. What you use depends on many things like the amount of data you want to precalculate. Just read the document and it will give you some ideas.

Well, i still have this problem:

I mainly understand plane equations and ray plane intersections but i failed to understand how i can get the plane origin (actually i couldn''t find anything on that ).

Can you guys help me out ? Thanks

What do you mean by origin exactly? A plane doesn''t have an origin. There is ofcourse an origin of the space where the plane is defined in. if the plane would have been:

ax + by + cz = 0 It goes through the origin. Otherwise it''s shifted by the d.

for example 0*x + 0*y + 5*z = 2
is a plane at z = 2/5 for any x and y...

maybe you understand now (maybe u allready did) that the origin (that i think you''re talking about) is the origin you''re plane equation is defined in.

hope it helps.
Marty