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Thomas de Groot <tho### [at] degrootorg> wrote:
> Well, I am interested in modelling wind patterns over a reed field, or a
> corn field. What I seem to observe are turbulent wave patterns moving
> the stalks back and forward while going over the field.
>
> This is a first approximation. I am not really satisfied yet with the
> pattern. What I did is:
>
> 1) Make an image_map with a more or less turbulent ripple pattern.
> 2) Make a height_field based on that image_map.
> 3) Build a reed stalk with Inverse Kinematic properties (macro with Bend
> parameter).
> 4) Select random locations on the height_field;
> 4a) calculate the vertical angle between the normal at that location and
> a horizontal plane (using: VAngleD(V1,V2));
> 4b) calculate the horizontal angle between (arbitrarily) the +z-axis
> direction (direction of primary bending of the reed stalks) and the
> normal of the random location point (using: VRotationD(V1,V2,axis)).
> 5a) bend the stalk with a proportion of the vertical angle (4a);
> 5b) orient the bended stalk by rotating through the horizontal angle (4b);
> 5c) place the reed stalks at the random locations on a flat surface.
>
> The image shows 15000 reed stalks. About 4.5 minutes render time.
>
> suggestions are more than welcome of course.
>
> Thomas
Wow, like a painting.
What are the povray objects you use?
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From: Thomas de Groot
Subject: Re: Proof of concept: The wind in the reeds
Date: 18 Sep 2014 03:25:57
Message: <541a8905@news.povray.org>
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On 17-9-2014 22:34, MichaelJF wrote:
> Looks very much better in my eyes. In fact I'm working on a somewhat similiar
> issue at the moment. That is why I came up with suggestions to control the
> bending and length of the straws depending on the position (and the normal
> provided by the trace()-command). I'm trying to give a certain model a special
> hair-style. (Stephen will recognize the source of my inspiration most likely.) I
> admit, there is room to improvement...
Ah yes, I can see the similarities indeed. Interesting hair model!
There is great potential in using the normal. In my case length control
does not make really sense, derived from the normal - except if I were
using /another/ image_map for controlling reed height in determined
areas; evalpig would be my friend in that case.
Thomas
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From: Thomas de Groot
Subject: Re: Proof of concept: The wind in the reeds
Date: 18 Sep 2014 03:28:40
Message: <541a89a8@news.povray.org>
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On 18-9-2014 1:43, Jörg 'Yadgar' Bleimann wrote:
> And they do not intersect each other? That in fact would be stunning!
Alas! There is no collision control available. However, intersections
are probably only visible to the really discerning eye ;-)
Thomas
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From: Thomas de Groot
Subject: Re: Proof of concept: The wind in the reeds
Date: 18 Sep 2014 03:34:11
Message: <541a8af3@news.povray.org>
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On 18-9-2014 7:25, And wrote:
> Wow, like a painting.
>
> What are the povray objects you use?
>
Thanks. Mesh2 objects, modelled in Silo. This one still has a couple of
small issues that need correction. When finished, I shall upload
everything to p.b.s-f.
Thomas
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Hi Thomas,
This is looking really great, I pobably am missing some step but how exactly can
you bend a mesh2 object in pov?
Thanks
Sean
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On 18-9-2014 10:08, s.day wrote:
> Hi Thomas,
>
> This is looking really great, I pobably am missing some step but how exactly can
> you bend a mesh2 object in pov?
>
I shall upload the model soon, when I have finished some corrections.
In the mean time, you need to build the model following inverse
kinematic principles. This means that the model subdivided in discrete
elements and articulated at their juncture, but not in a haphazardly
way. Here follows the construction of the reed stalk as I use it. You
can already study its inner workings:
#macro Reed(Bend)
//random rotation for the whole stalk:
#local Rot = RRand(-180, 180, R);
//construction of the Inverse kinematic stalk:
#local Bend1 = Bend+((2*Bend)/10);
#local Plume =
union {
object {ReedMesh_03_ik_Reed01_plume_ material{Reed01_plume_} hollow
translate -10.40*y rotate Rot*y rotate Bend1*x translate (10.40-10.18)*y }
object {ReedMesh_03_ik_Reed01_11_ material{Reed01_11_} hollow
translate -10.18*y rotate Rot*y}
}
#local Bend2 = Bend+(Bend/10);
#local Top =
union {
object {Plume rotate Bend2*x translate (10.18-9.86)*y}
object {ReedMesh_03_ik_Reed01_10_ material{Reed01_10_} hollow
translate -9.86*y rotate Rot*y}
}
#local Stem9 =
union {
object {Top rotate Bend*x translate (9.86-9.54)*y}
object{ReedMesh_03_ik_Reed01_9_ material{Reed01_9_} hollow translate
-9.54*y rotate Rot*y}
}
#local Bend = Bend-(Bend/20);
#local Stem8 =
union {
object {Stem9 rotate Bend*x translate (9.54-9.165)*y}
object{ReedMesh_03_ik_Reed01_8_ material{Reed01_8_} hollow translate
-9.165*y rotate Rot*y}
}
#local Bend = Bend-(Bend/20);
#local Stem7 =
union {
object {Stem8 rotate Bend*x translate (9.165-8.79)*y}
object{ReedMesh_03_ik_Reed01_7_ material{Reed01_7_} hollow translate
-8.79*y rotate Rot*y}
}
#local Bend = Bend-(Bend/20);
#local Stem6 =
union {
object {Stem7 rotate Bend*x translate (8.79-7.72)*y}
object{ReedMesh_03_ik_Reed01_6_ material{Reed01_6_} hollow translate
-7.72*y rotate Rot*y}
}
#local Bend = Bend-(Bend/20);
#local Stem5 =
union {
object {Stem6 rotate Bend*x translate (7.72-6.20)*y}
object{ReedMesh_03_ik_Reed01_5_ material{Reed01_5_} hollow translate
-6.20*y rotate Rot*y}
}
#local Bend = Bend-(Bend/20);
#local Stem4 =
union {
object {Stem5 rotate Bend*x translate (6.20-4.65)*y}
object{ReedMesh_03_ik_Reed01_4_ material{Reed01_4_} hollow translate
-4.65*y rotate Rot*y}
}
#local Bend = Bend-(Bend/20);
#local Stem3 =
union {
object {Stem4 rotate Bend*x translate (4.65-3.10)*y}
object{ReedMesh_03_ik_Reed01_3_ material{Reed01_3_} hollow translate
-3.10*y rotate Rot*y}
}
#local Bend = Bend-(Bend/20);
#local Stem2 =
union {
object {Stem3 rotate Bend*x translate (3.10-1.55)*y}
object{ReedMesh_03_ik_Reed01_2_ material{Reed01_2_} hollow translate
-1.55*y rotate Rot*y}
}
#local Bend = Bend-(Bend/20);
#declare ReedMesh_03 =
union {
object {Stem2 rotate Bend*x translate 1.55*y}
object{ReedMesh_03_ik_Reed01_1_ material{Reed01_1_} hollow rotate Rot*y}
}
#end //macro
As you can see, the construction starts at the top of the stalk and
gradually incorporates adjacent elements until the base is reached. Note
that /only/ rotations can be used as transformations inside the IK
model. All other transformations must be applied to the /complete/ model
or not at all. Note also that /all/ internal rotations of the model are
applied *at the origin*.
Thomas
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Thomas de Groot <tho### [at] degrootorg> wrote:
> I shall upload the model soon, when I have finished some corrections.
>
> In the mean time, you need to build the model following inverse
> kinematic principles. This means that the model subdivided in discrete
> elements and articulated at their juncture, but not in a haphazardly
> way. Here follows the construction of the reed stalk as I use it. You
> can already study its inner workings:
>
Thanks Thomas,
I hadn't thought about having separate sections, I thought you were somehow
bending the acutal mesh (doh!).
Sean
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From: Thomas de Groot
Subject: Re: Proof of concept: The wind in the reeds
Date: 19 Sep 2014 08:19:18
Message: <541c1f46@news.povray.org>
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I have attached my code and the used reed stalk, in p.b.s-f.
Explore and enjoy!
Thomas
Post a reply to this message
Attachments:
Download 'wind_pattern.png' (662 KB)
Preview of image 'wind_pattern.png'
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"s.day" <s.d### [at] uelacuk> wrote:
> Hi Thomas,
>
> This is looking really great, I pobably am missing some step but how exactly can
> you bend a mesh2 object in pov?
>
> Thanks
>
> Sean
If you have a proper inside vector you can bend mesh2 objects with the approach
by Chris Colefax. In this case, mesh2 objects can be handled like other CSG
objects (spheres, boxes and so on). I have done this with my snails
(http://www.tc-rtc.co.uk/imagenewdisplay/stills/index345.html) which consists of
a mesh2 object and a blob with thousands of components. In fact I did not
understood Chris's parameters and wrote an own approach, but very similiar to
Chris, since I judged it easier to implement it by myself than to understand his
parametrisations.
@Thomas: The Mud Maid at the "Lost Gardens of Heligan" (I spend my holydays this
year very close to this garden) is a sculpture consisting of mud, clay, cement,
gras, ivy and moss and she is laying at the left side of her body to the ground,
so no much grass at the left side if standing;-)
Best regards,
Michael
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On 20-9-2014 19:51, MichaelJF wrote:
> If you have a proper inside vector you can bend mesh2 objects with the approach
> by Chris Colefax. In this case, mesh2 objects can be handled like other CSG
> objects (spheres, boxes and so on). I have done this with my snails
> (http://www.tc-rtc.co.uk/imagenewdisplay/stills/index345.html) which consists of
> a mesh2 object and a blob with thousands of components. In fact I did not
> understood Chris's parameters and wrote an own approach, but very similiar to
> Chris, since I judged it easier to implement it by myself than to understand his
> parametrisations.
Not sure, but I think that /bending/ an object will be much slower to
render, especially if there are 15000 of them ;-)
>
> @Thomas: The Mud Maid at the "Lost Gardens of Heligan" (I spend my holydays this
> year very close to this garden) is a sculpture consisting of mud, clay, cement,
> gras, ivy and moss and she is laying at the left side of her body to the ground,
> so no much grass at the left side if standing;-)
Ah yes, the Lost Gardens! I unfortunately missed those when I stayed in
Penzance many years ago. Only much later I heard about them. I hope
/your/ Mud Maid will make it here or perhaps at the TC-RTC.
Thomas
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