newbie Q:

newbie Q:

Post by Igor Crnkovi » Thu, 03 Jul 2003 20:57:49



im working on a model of chemical element (NH4).

how to put stick like object,that is connecting two spheres, to begin in
centre of one, and end in centre of another sphere.

thnx very much

 
 
 

newbie Q:

Post by Igor Crnkovi » Fri, 04 Jul 2003 18:55:00



Quote:

> im working on a model of chemical element (NH4).

> how to put stick like object,that is connecting two spheres, to begin
> in  centre of one, and end in centre of another sphere.

> thnx very much

i didn't explain it very well. I mean how to give it angle an
coordinates, not to position it manualy.

thnx again

 
 
 

newbie Q:

Post by Frank Bus » Thu, 10 Jul 2003 11:27:57




>> im working on a model of chemical element (NH4).

>> how to put stick like object,that is connecting two spheres, to begin
>> in  centre of one, and end in centre of another sphere.

I don't know, how you can align an object to the center of an sphere,

Quote:> i didn't explain it very well. I mean how to give it angle an
> coordinates, not to position it manualy.

but if you want to enter the coordinates, that's possible. For NH4 there
are 4 H atoms in a tetrahedron around a N atom, so we have to calculate the
edges of a tetrahedron, first:

http://www.frank-buss.de/tmp/tetrahedron.jpg

If you start like this with the left edge at (0, 0, 0), then the center
will be at (a/2, sqr(3)*a/6, a/2/sqr(6)). So if you choose a=100, the
center will be at (50, 28.8675, 20.4124) and the four surounding points
will be at (0, 0, 0), (100, 0, 0), (50, 86.6025, 0) and (50, 28.8675,
81.6497). In Cinema 4D you must specify the radius (the distance between an
edge and the center), which is a*sqr(3/2)/2, for a=100 it is 61.2372.

Ok, now construct your NH4 with sticks. First the sticks:

- add a new platonic object
- change type to "Tetra" and set radius to 61.237 (in the "Object" card)
- rotate P: 90 and B: 180
- enter "C" to make it editable
- change position to x: 0, y: 0 and z: 0,
- make 3 copies
- change position from copy 1 to x: 100
- change position from copy 2 to x: 50 and y: 86.6025
- change position from copy 3 to x: 50, y: 28.8675 and z: 81.6497
- select the first object and scale it to 0.2
- select the 2. object and scale it to 0.2
- select the 3. object and scale it to 0.2
- select the 4. object and scale it to 0.2
- extrude the ploygon from the first object to the center
- the same for the other three polygons
- do "Normal Move" to adjust the endpoints, if necessary

Now it should look like this:

http://www.frank-buss.de/tmp/sticks.jpg

If you want round sticks, try to add the objects to HyperNURBS. Delete one
end point and scale the center end to make it tubes.

Now the atoms:

- add a sphere with radius 20 at the center at x: 50, y: 28.8675 and z:
20.4124
- add 4 spheres with radius 15 at (0, 0, 0), (100, 0, 0), (50, 86.6025, 0)
and (50, 28.8675, 81.6497)

After adding some background, material, light and copying the molecule, you
should see something like this:

http://www.frank-buss.de/tmp/nh4.jpg

Note: I'm a Cinema 4D newbie, too, and I'm sure that there is an easier way
to construct the molecule, but at least this description works.

--

http://www.frank-buss.de, http://www.it4-systems.de

 
 
 

newbie Q:

Post by Frank Bus » Fri, 11 Jul 2003 07:20:37



> Note: I'm a Cinema 4D newbie, too, and I'm sure that there is an
> easier way to construct the molecule, but at least this description
> works.

It is really simple:

- create a cylinder with radius 20 and height 200
- hit "C" for "Make Editable"
- "Use Object Axis Tool" and change y = 100
- add a sphere with radius 50
- change y = -100
- group the sphere below the cylinder in the objects view
- select the cylinder
- "Use model tool" and change y = 0 (because the sphere is grouped, it
should move with the cylinder)

Ok, some math is still needed for perfect results: I calculated that the
angle between two polygons is arcussin(2*sqr(2)/3), which is ca. 70.5288
degree. So the second cylinder needs to be rotated by 180+70.5288=250.529
degree and the third and fourth cylinders from this point additional +120
and -120 degree around the other axis:

- copy and paste the cylinder
- rotate p = 250.529
- copy and paste the cylinder
- rotate h = 120
- copy and paste the cylinder
- rotage h = -120

At this point it should look like this:

http://www.frank-buss.de/tmp/sticks2.jpg

And last you can add another sphere with radius 100 at the center and add
some material:

http://www.frank-buss.de/tmp/nh4_2.jpg

--

http://www.frank-buss.de, http://www.it4-systems.de

 
 
 

newbie Q:

Post by Igor Crnkovi » Sat, 12 Jul 2003 17:48:07


THANK YOU!!!!

this is the aproach I was looking for !
It'll be helpfull for future work too.
I'll try it this afternoon.

again thnx a lot

igor

 
 
 

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