http://www.sohcahtoa.net/videos/amazinggrace.m1v

This roller coaster is called Amazing Grace.  It was designed by RiscIt, 
one of the admins of CoasterSims.com.  The actual track looks FAR better 
in No Limits, because he uses terrain and 3DS objects, both of which I 
have not implemented yet.  Also, the lack of supports kind of takes a 
bit away from the feel of the ride.

That said, this represents the fact that I've fixed my banking problem 
in that corkscrews and loops work (See my post on p.general), though 
loops with little lateral movement will show a glitch, which shows 
itself in one of the loops in this ride.

I need to change the method of interpolation though...through the 
corkscrews, the ride kind of wobbles because the interpolation is 
linear.  I know that No Limits uses some sort of bezier interpolation, 
but I'm not sure how exactly to implement it for banking.  I might 
settle for 3rd order b-spline interpolation.  While it may end up being 
very smooth, it won't be as accurate to the original track.

-DJ

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Simply amazing... There's something to be said for framerates, and 
having a constant one :)  My computer is, unfortunately, old enough that 
the coaster sims struggle a lot.  I also like the shadows.  Overall, it 
gave me a much more favorable impression than RCT does.  Good job!

...Chambers

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Chambers wrote:

> Simply amazing... There's something to be said for framerates, and 
> having a constant one :)  My computer is, unfortunately, old enough that 
> the coaster sims struggle a lot.  I also like the shadows.  Overall, it 
> gave me a much more favorable impression than RCT does.  Good job!
> 
> ...Chambers

Currently re-rendering it using 600 fps...the plan is to turn it into 60 
fps with 10-sample motion blur.  Its gonna look SMOOOOOOOOTH.

Meanwhile, I'll be working on getting supports going.

-DJ

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DJ Wiza wrote:
> Currently re-rendering it using 600 fps...the plan is to turn it into 60 
> fps with 10-sample motion blur.  Its gonna look SMOOOOOOOOTH.
> 
> Meanwhile, I'll be working on getting supports going.
> 
> -DJ

I've cancelled this render.  Its going to take too long.  I'd rather 
save that kind of render for when I get terrain and supports done, that 
way it looks perfect.

-DJ

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If you require any rendering done I have a lot of CPU time I could 
spare.  Also I get to see how you are working things ;)

Let me know.

Dave.

DJ Wiza wrote:
> DJ Wiza wrote:
>> Currently re-rendering it using 600 fps...the plan is to turn it into 
>> 60 fps with 10-sample motion blur.  Its gonna look SMOOOOOOOOTH.
>>
>> Meanwhile, I'll be working on getting supports going.
>>
>> -DJ
> 
> I've cancelled this render.  Its going to take too long.  I'd rather 
> save that kind of render for when I get terrain and supports done, that 
> way it looks perfect.
> 
> -DJ

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Man! This track is insane! 8-O
If anybody will ever build this please let me know :D
I'm glad you could fix the corkscrew problem and i hope you'll get this loop
thingy fixed as well!

Would it be a problem to provide another Divx version of that one like you
did the last times? it just looks much better that way.

If you need a few extra frames to be rendered (or webspace for divx versions
;)) i could help you with that as well. Just let me know.

Waiting for more to come!
Regards Roman

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DJ Wiza <Kil### [at] sohcahtoanet> wrote:
> http://www.sohcahtoa.net/videos/amazinggrace.m1v
>
> This roller coaster is called Amazing Grace.  It was designed by RiscIt,
> one of the admins of CoasterSims.com.  The actual track looks FAR better
> in No Limits, because he uses terrain and 3DS objects, both of which I
> have not implemented yet.  Also, the lack of supports kind of takes a
> bit away from the feel of the ride.
>
> That said, this represents the fact that I've fixed my banking problem
> in that corkscrews and loops work (See my post on p.general), though
> loops with little lateral movement will show a glitch, which shows
> itself in one of the loops in this ride.
>
> I need to change the method of interpolation though...through the
> corkscrews, the ride kind of wobbles because the interpolation is
> linear.  I know that No Limits uses some sort of bezier interpolation,
> but I'm not sure how exactly to implement it for banking.  I might
> settle for 3rd order b-spline interpolation.  While it may end up being
> very smooth, it won't be as accurate to the original track.
>
> -DJ

Got any barf bags?  That was kind of fun.

As a note, you have a kink in your track, ascending the loop at about the
38sec mark.

-tgq

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Trevor G Quayle wrote:
> DJ Wiza <Kil### [at] sohcahtoanet> wrote:
> 
>>http://www.sohcahtoa.net/videos/amazinggrace.m1v
>>
>>This roller coaster is called Amazing Grace.  It was designed by RiscIt,
>>one of the admins of CoasterSims.com.  The actual track looks FAR better
>>in No Limits, because he uses terrain and 3DS objects, both of which I
>>have not implemented yet.  Also, the lack of supports kind of takes a
>>bit away from the feel of the ride.
>>
>>That said, this represents the fact that I've fixed my banking problem
>>in that corkscrews and loops work (See my post on p.general), though
>>loops with little lateral movement will show a glitch, which shows
>>itself in one of the loops in this ride.
>>
>>I need to change the method of interpolation though...through the
>>corkscrews, the ride kind of wobbles because the interpolation is
>>linear.  I know that No Limits uses some sort of bezier interpolation,
>>but I'm not sure how exactly to implement it for banking.  I might
>>settle for 3rd order b-spline interpolation.  While it may end up being
>>very smooth, it won't be as accurate to the original track.
>>
>>-DJ
> 
> 
> Got any barf bags?  That was kind of fun.
> 
> As a note, you have a kink in your track, ascending the loop at about the
> 38sec mark.
> 
> -tgq
> 
> 

I know about the kink, that's why I noted above that vertical loops with 
very little lateral movement will show a glitch.

The problem is with vertical track.  If a track is exactly 90 degrees 
down, how do you know which way is up?  To make an up vector, I use 
VPerp_To_Plane to find a vector that is perpendicular to a plane defined 
by a vector that points "foward" along the track and the vector y.  This 
creates a vector pointing right.  I then use vaxis_rotate to rotate that 
by the amount of banking defined by the track.

Of course, this creates the problem that as track gets closer and closer 
to going 90 degrees either straight up or down, you get rounding errors 
that result in those kinks.

The author of No Limits found a way around it by allowing the user to 
specify that a banking angle is "relative" to the previous control 
points banking.  Not sure how I could implement that though.  I might 
have to do a lot of reworking.

-DJ

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David Brickell wrote:

> If you require any rendering done I have a lot of CPU time I could 
> spare.  Also I get to see how you are working things ;)
> 
> Let me know.
> 
> Dave.
> 

Test renders are quick.  Because I'm using spheres/cylinders rather than 
sphere_sweeps, it only takes about 6 seconds per frame, and most of my 
test renders are just single frames to make sure something is being 
calculated correctly.

-DJ

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> The problem is with vertical track.  If a track is exactly 90 degrees
> down, how do you know which way is up?  To make an up vector, I use
> VPerp_To_Plane to find a vector that is perpendicular to a plane defined
> by a vector that points "foward" along the track and the vector y.  This
> creates a vector pointing right.  I then use vaxis_rotate to rotate that
> by the amount of banking defined by the track.
>
> Of course, this creates the problem that as track gets closer and closer
> to going 90 degrees either straight up or down, you get rounding errors
> that result in those kinks.

I've once written a small script to create a mesh-tube running along a
spline, and ran into similiar problems. What was suggested to me then by
Rune and someone else who's name I've forgotten (sorry) to update the
up-vector successively, instead of independantly for each frame (in my case,
for every ring of the tube, in your case, it's the frames).

I start with the initial direction I'm heading to, and an initial up vector.
On the next frame, use the old up-vector, and double vcross it with the new
direction to get the new up-vector.

  #local Up = vnormalize(vcross(vcross(New_Direction,Last_Up),
New_Direction));

Since the new direction and the old up-vector aren't perpendicular, you'll
create a new up-vector that is aligned along the plane defined by the old
up-vector and new-direction... Quite simple, once you think it through.

Additionally, since this only affects corkscrew or other loopings, you could
create a parsing step that'll just do that when it's needed. Needs a little
more though, but would be worthwhile in case you plan on distributing the
render and making the animation independant of former frames.

Regards,
Tim

-- 
aka "Tim Nikias"
Homepage: <http://www.nolights.de>

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