WARNING: (fairly basic) math/geometry inside. Number-allergic people can skip :P
Hi all,
I think I managed to create some sort of visual representation of the .geom file of GPB. Two important points first:
- This stuff is messy, hence I'm not 100% sure it is correct. Looks correct to me, but only Piboso could confirm. I doubt he'll waste his precious time to do this (and I can't blame him for that decision) so ...
- Thanks to neoraptor, who had the initial (and smart) idea to use GeoGebra for that task !
You can use GeoGebra in your browser (GeoGebra Web (http://www.geogebra.org/webstart/geogebra.html)) but the standalone application (Downloads (http://www.geogebra.org/cms/en/download/)) works better for me. In any case, it's free.
I've attached the .ggb file: it contains the 990 data in the "Spreadsheet".
If you want to change some data manually it is possible. If youwant to put another .geom model, do this:
- Copy/Paste the entire .geom file (except the collision sections) into Excel/ or similar (I used LibreOffice)
- Normally it will ask you to parse the data as a fixed/delimited file: use dleimited with "=" and "," as separators.
- Now select all the lines between "type" and "t-cam" (4 columns, A-D), copy it and thenm paste it into GeoGebra Spreadsheet (starting from the right cell, A4).
- You will have to enter manually the wheel sizes (front, rear) in cells B1 and B2: you can find them in GPB .tyre files (at the end, "Radius").
The sliders allow to change the bike configuration: SwingArm length, SwingArmPivot (no effect in GPB at the moment) and Rake are bike's parameters, while FLength and SwingRot are the "state" of the suspensions (how much the front fork is extended and how much the rear swingarm is rotated).
There are 2 bikes shown: the one the top is in the chassis reference frame, the wheels do not touch an horizontal line.
The one on the bottom is in the "world" frame: here the road is horizontal and the wheels are on it.
On the top part you have the individual components in their own reference system. You cam move them moving around the O* points (no impact on anything).
One thing you can see is how the various parameters influence important quantities as Wheelbase, effective rake, trail etc.
One thing I don't know at all , is what "rear_length" does in the .geom file. It seems to have no effect at all.
MaX.
thx Max and Neo 8)
This allow us to figure out how works geom in gpbikes :)
I have 2 questions now :
1) How should I put the chassis, the fork and the swing arm in 3dsmax scene before export ?
2) How should I collect all the coordinates points ?
3) is there a specific point defines as reference who would be at the center of the 3dsmax scene univers ? or can we just put the model as we want and after define the new location of each points ?
Quote from: JC#21 on January 25, 2014, 08:24:44 AM
I have 2 questions now :
Cheater :)
Quote from: JC#21 on January 25, 2014, 08:24:44 AM
1) How should I put the chassis, the fork and the swing arm in 3dsmax scene before export ?
I have no idea: 3d modelling is really something I do
not plan to look into, no time for that.
But for sure our modders know, given we already have plenty of bikes working.
For my tool it doesn't really matter, as far as iot is OK for GPB.
Quote from: JC#21 on January 25, 2014, 08:24:44 AM
2) How should I collect all the coordinates points ?
Which coord points ? The O* (O
sw, O
fu, O
st, O
ch) ?
These are just offsets to be able to move the components around.
In the .geom file they are all assumed to be in (0,0), then each component is moved to its correct position.
Quote from: JC#21 on January 25, 2014, 08:24:44 AM
3) is there a specific point defines as reference who would be at the center of the 3dsmax scene univers ? or can we just put the model as we want and after define the new location of each points ?
Can't answer this. I suspect that in 3ds you'll have to model/export each part separately and each will have his own reference point. In the .geom file, the points of a component are relative to that reference point. Example:
- Swingarm in 3ds has reference point Osw in (5,5) (let's keep it 2d). The swingarm joint is 1 left of this point, so in (4,5).
- In the .geom file, the coord of the joint will be (-1,0).
- In my tool you can move around Osw as you want, but the joint will always be 1 left of Osw
MaX.
Max have you understand this part of the geom file ?
rip_leftpos = -0.25, 0.2, -0.1
grip_leftdir = 1, 0, 0
grip_rightpos = 0.25, 0.2, -0.1
grip_rightdir = 1, 0, 0
I have tried to change the values but nothing change ingame
other question, I would like create the box colision with this information :
box0 = 0, -0.05, -0.45, 0.33, 0.18, 0.5, 0.19
but do you know how it works ? how should I read it ? length, width, height, ... ???
It's ok for the box code except the last 0.19.
For the other codes, I have no idea :-(
Looks like the hands position (in some reference frame) but ...
Maybe ODi knows (not sure from what I see in his .geom files).
But Piboso may know :)
MaX.
Do you know what is the pressure_center ?
Quote from: JC#21 on June 02, 2014, 04:23:16 PM
Do you know what is the pressure_center ?
The pressure center is the point at which the aerodynamic forces are applied (and around which axes the aero moments are applied).
MaX.
Quote from: HornetMaX on June 02, 2014, 06:21:58 PM
The pressure center is the point at which the aerodynamic forces are applied (and around which axes the aero moments are applied).
MaX.
thx Max :)
Sometimes I feel like this
(http://asset-6.soup.io/asset/1660/6871_6dbd.jpeg)
I'm gonna search more information about it and geom of motorcycle in general
Quote from: JC#21 on June 02, 2014, 09:50:39 PM
I'm gonna search more information about it and geom of motorcycle in general
Here: http://forum.piboso.com/index.php?topic=1165.0 (http://forum.piboso.com/index.php?topic=1165.0)
MaX.
Quote from: JC#21 on May 28, 2014, 10:38:32 AM
It's ok for the box code except the last 0.19.
For the other codes, I have no idea :-(
I think that is the radious of the sphere.
Quote from: Alone on June 06, 2014, 08:04:20 PM
Quote from: JC#21 on May 28, 2014, 10:38:32 AM
It's ok for the box code except the last 0.19.
For the other codes, I have no idea :-(
I think that is the radious of the sphere.
The radius of the sphere in a box ?
MaX.
I think that is the radious of the sphere.
[/quote]
The radius of the sphere in a box ?
MaX.
[/quote]
hahaha, I feel like an idiot :-[ Bad read, I thought that he was asking for the fsusp...so, no idea ;D
Noob question.. Can I use GeoGebra to adjust the tyre size/shape in-game?
Or are changes to the 3d model and everything else needed too?
Be kind lol ;D
Quote from: BOBR6 84 on September 01, 2015, 08:23:10 AM
Noob question.. Can I use GeoGebra to adjust the tyre size/shape in-game?
No.
Quote from: BOBR6 84 on September 01, 2015, 08:23:10 AM
Or are changes to the 3d model and everything else needed too?
It depends: do you want the tyre to look bigger or to feel (behave) bigger ?
For the 1st it's the 3d model, for the 2nd its the physics.
Quote from: BOBR6 84 on September 01, 2015, 08:23:10 AM
Be kind lol ;D
I'm always kind, no ? :D
MaX.
Yeah, to change the behaviour would be just fine! No chance of doing any 3d stuff haha
Just taking a look through the bike modding wiki, id like to figure out how to play around with the tyres.. Sizes, grip levels etc
So GeoGebra is used as a visual guide?
To be honest MaX, you are kind! ;D straight to the point.. I like it ;)
If I changed the tyres on the 600 from lets say 180/55 to 190/60 wouldnt it look strange in-game? Like a slight gap between tyre/track surface?
Quote from: BOBR6 84 on September 01, 2015, 09:31:50 AM
So GeoGebra is used as a visual guide?
Yes, it was just a way to visualize the bike geometry when we had to figure out what the different geom parameters were.
Quote from: BOBR6 84 on September 01, 2015, 09:55:39 AM
If I changed the tyres on the 600 from lets say 180/55 to 190/60 wouldnt it look strange in-game? Like a slight gap between tyre/track surface?
If the overall tyre diameters stays constant you will have no gap.
Notice however that GPB tyres are not described as real life tyres (i.e. 180/55 R16).
The relevant parameters (for tyre size) are the tyre radius, the tyre torus radius and the "width" (which I suspect to be the half-angle of the tyre profile width, in fact).
Out of memory, for the 990 murasama, these are 325mm, 130mm and 60deg.
For grip levels: if you only want to alter the overall grip (on the different surfaces) that's pretty easy. Anything else is a bit trickier and you'll have to read about the Pacejka's MF model (the stuff displayed by MaxTyre).
BTW: that reminds me of an unanswered potential issue on tyres ... http://forum.piboso.com/index.php?topic=1922.msg25790;topicseen#msg25790 (http://forum.piboso.com/index.php?topic=1922.msg25790;topicseen#msg25790)
MaX.
Thanks very much!
The pacejka formula is too complex for me. Doubt il make any sense of that but il take a look anyway.
For the tyre dimensions, Width.. So its measured from the top/centre?
Would be nice to undestand the tyre model but hey ho.. To adjust the overall surface grip levels that wont let me tune side slip and all that good stuff will it? :-\
Ps. Why no reply from piboso I wonder on your thread link? ???
Quote from: BOBR6 84 on September 01, 2015, 01:23:43 PM
For the tyre dimensions, Width.. So its measured from the top/centre?
As far as i understand it, the GPB tyre is a torus (https://en.wikipedia.org/wiki/Torus). With the conventions of the wikipedia page:
R is the distance from the center of the tube to the center of the torus,
r is the radius of the tube.GPB has R+r = 325mm and r = 130mm (for the murasama).
To figure out the tyre widht, the only thing I can come up with is: the 60 indicates the half-angle of the tyre profile, i.e. the green angle in this post (here (http://forum.piboso.com/index.php?topic=2555.msg37516#msg37516)) is 2*60= 120 degrees.
If that's correct (but here too, it would be nice to have a confirmation from Pib) then the tyre width as we intend it (e.g. 180mm, 190mm etc) is computed as 2*r*sin(60deg) = 2*130mm*sin(60deg) = 225mm. That seems a bit big, even for a MotoGp tyre (officially, current Bridgestone are "only" 190).
Quote from: BOBR6 84 on September 01, 2015, 01:23:43 PM
Would be nice to undestand the tyre model but hey ho.. To adjust the overall surface grip levels that wont let me tune side slip and all that good stuff will it? :-\
No, to do that you'd have (at least) to play with the Pacejka model of the tyre.
Quote from: BOBR6 84 on September 01, 2015, 01:23:43 PM
Ps. Why no reply from piboso I wonder on your thread link? ???
You search me.
MaX.
Nice one MaX! thanks very much.. good info ;) btw.. completely forgot about the tyre measurements :-[ still want them??
Quote from: BOBR6 84 on September 02, 2015, 04:54:09 PM
Nice one MaX! thanks very much.. good info ;) btw.. completely forgot about the tyre measurements :-[ still want them??
Only if you have time to waste. Anyway they are only potentially useful if Piboso takes a look, so ... not exactly granted.
MaX.