Comments on: Little Longhorn – Part 3 – Collision, Detection and Selection (Help needed)

By: Sergey

Sergey — Thu, 30 Jul 2009 04:36:55 +0000

It’s ok – expressive smiles must be large :)

By: Mads

Mads — Wed, 29 Jul 2009 08:20:57 +0000

1. I have tried it only once actually. I’m using FireFox normally and it doesn’t hang for me. Sadly I can’t reproduce the problem, so don’t know whats wrong and can’t fix it.

2. I know, even though I’m refering to the Joel Neubeck articles pretty much, they are not THE right way and completely error free. Actually he had a pretty bad bug in the Vector struct, which is used pretty many places. Right now I’m using the collision code, pretty much as he provided it, because it works right now, and then later on I will go back and optimize it.

PS: Damm, comments look like crap here on my blog, when there are smilies in them. I need to look into that. :)

By: Mads

Mads — Wed, 29 Jul 2009 08:16:25 +0000

Hi Sergey
First of all, thanks for taking your time an read the entire post, I was a long one, too long I have learned.

I have created a post on the silverlight forum, linking to this post, hoping people could help me from there: http://betaforums.silverlight.net/forums/t/114354.aspx

1. It had a "sliding" effect. I actually knew that setting the Velocity to 0 wasn’t what I needed, I just tried it out for fun. There are a post in the forum thread talking about how I can make this work. Haven’t had time to look at this "Block" collision yet.

3. Well, I see what you mean, but for me the code need to make sense. I’m currently working on a solution about this "Detection" and "Selection" stuff, it doesn’t work right now, but I’m sure I’m on the right track, just need time to implement it fully. I got the idea for the implementation I’m currently working on by talking to Cameron Albert and reading the posts on the silverlight.net forum thread.

By: Sergey

Sergey — Wed, 29 Jul 2009 03:19:04 +0000

P.S.

1. Your site(blog) hangs up my Firefox all the time while loading :)

2. Be careful with Joel Neubeck’ articles: there are enough logical errors. Also some of his code is too complicated, for example colliding bounging box and sphere. Here is how it looks in my code now:

static public bool Check(BoundingBox b, BoundingSphere s)
{
Vector shiftCenter = AbsVector(b.Center – s.Center);
double extX = b.Extent.X + s.Radius;
double extY = b.Extent.Y + s.Radius;

if (shiftCenter.X <= extX && shiftCenter.Y <= extY)
{
b.Hit = s.Hit = true;
return true;
}

return false;
}

Best Regards :)

By: Sergey

Sergey — Wed, 29 Jul 2009 03:03:57 +0000

1. You said in “Block” collision: …but it didn’t have the right effect :)
But what effect it had??

2. “Detection” of enemies

I think you act quite right.

3. “Selection” of elements: ..this is also a kind of “collision”, but at the same time it’s conceptually not, because nothing is actually colliding logically.

What I think about it:

– It’s doesn’t matter about your conceptual confusion if it works well :) . As you said before in answer to my post: "let the pattern be the solution to my problems, not a barrier", now replace the word "pattern" with "concept" :)
– You can just find the closest center of your "building" spot to your character’s center because there may be more then one spots next to it and there may be trouble while using collision to detect it (which of two spots to shoose?). But anyway even in this case you can choose only the first one and skip the others.