118 reputation
7
bio website justinmchase.com
location St Paul, MN
age
visits member for 3 years, 8 months
seen 20 hours ago

I am a member of the Microsoft Expression team based on St. Paul Minnesota. I also work on some open source projects in my spare time (http://metasharp.codeplex.com).


Sep
24
awarded  Autobiographer
Dec
5
comment Detecting if an object is following a path
Actually I think that was exactly what I needed, thanks again.
Dec
5
accepted Detecting if an object is following a path
Dec
5
comment Detecting if an object is following a path
That is a great link though, I will have to reconsider this. Thanks.
Dec
5
comment Detecting if an object is following a path
Yes the points form lines, though with U-turns and looping on ramps it gets pretty interesting. I actually started out with what you were recommending but found that it had problems with U-turns, where a point further down the path might actually be closer to your current position which is actually between two earlier points.
Dec
5
asked Detecting if an object is following a path
Mar
30
comment Matrix rotation of a rectangle to “face” a given point in 2d
In reality I'm using a rectangle, it looks good. Also a friend of mine showed me a way to do it without using trig. It's basically like this: var p = target.subtract(new Point(x, y)).normal(); then the matrix is: [p.y, -p.x, p.x, p.y, x, y]
Mar
30
accepted Matrix rotation of a rectangle to “face” a given point in 2d
Mar
30
comment Matrix rotation of a rectangle to “face” a given point in 2d
This may make me sound foolish but one revelation that I had while working on this was that position is not needed at all... the position information is encoded into the matrix. That was messing me up.
Mar
30
awarded  Scholar
Mar
30
awarded  Commentator
Mar
30
comment Matrix rotation of a rectangle to “face” a given point in 2d
Thanks a ton, this was almost exactly what I needed. I just submitted an edit to your answer with the actually working function for future reference. I will accept this as the answer.
Mar
30
suggested suggested edit on Matrix rotation of a rectangle to “face” a given point in 2d
Mar
30
comment Matrix rotation of a rectangle to “face” a given point in 2d
Thanks for your patience everyone. I'm realizing I'm thinking about things wrong. I'm getting closer.
Mar
30
awarded  Student
Mar
30
comment Matrix rotation of a rectangle to “face” a given point in 2d
Hmm, now how the heck would I translate that into 2d?
Mar
30
comment Matrix rotation of a rectangle to “face” a given point in 2d
Oh yes that looks good! I'm assuming the second part of the formula is the new matrix? The formatting there is pretty unfortunate.
Mar
30
comment Matrix rotation of a rectangle to “face” a given point in 2d
Whatever way is eaiser to explain I think. I was picturing the identity matrix and identity vector to essentially be the direction the rectangle was "facing" in the start state... but basically I want the top side of the rectangle to be considered the direction it is facing.
Mar
30
awarded  Editor
Mar
30
revised Matrix rotation of a rectangle to “face” a given point in 2d
Minor consistency update.