## Double Helix

Started by nikita, July 20, 2007, 05:52:13 pm

#### old_blaggard

##### July 21, 2007, 02:40:04 pm #15
Ah, that makes sense.  Thanks .
http://www.terragen.org - A great Terragen resource with models, contests, galleries, and forums.

#### bigben

##### July 21, 2007, 08:52:23 pm #16
Very cool nikita.

Maybe math teachers should introduce TG2 into classes to make math more interesting/ practical

#### Volker Harun

##### July 22, 2007, 03:18:22 am #17
Worth while patience! Thanks for sharing the technique!

#### Volker Harun

##### July 22, 2007, 04:06:59 am #18
What I do not understand, why do make x² and z², combine them to one scalar and make a square root - you can just delete all those nodes.

#### nikita

##### July 22, 2007, 07:51:52 am #19
sqrt(x²+z²) is not equal to x+z
(unlike sqrt(x²*z²) = x*y)

Of course you could delete those, but then you wont get a cone but a pyramid.

#### Volker Harun

##### July 22, 2007, 09:12:53 am #21
Hi Nikita,
well, x and z are not added in a numerous way but are combined to a scalar, where x and z are handled seperatly, aren't they.
For example x=4 and z=4 then the addition is (4|0|0)+(0|0|4)=(4|0|4) - if I should be right then the nodes can be deleted.
And a testrender shows a cone, not a pyramid.

#### nikita

##### July 22, 2007, 09:39:24 am #22
If I delete them, the cone turns into a wall or a pyramid if i add the necessary abs()'. There is no way you could get a cone without using at least the x2,z2 nodes.

This is the way how I understand it works:
X to scalar: (x,y,z) -> x (the function assigns to a vector its x-component [and doesn't remember that this has once been an x-value])
Y to scalar: (x,y,z) -> y
...

A scalar, that handled xyz seperately would be a vector. Why would we need the concept of a scalar if it was just a special form of vector?

#### Matt

##### July 22, 2007, 09:58:14 am #23 Last Edit: July 22, 2007, 10:02:55 am by Matt
Quote from: nikita on July 22, 2007, 09:39:24 am
If I delete them, the cone turns into a wall or a pyramid if i add the necessary abs()'. There is no way you could get a cone without using at least the x2,z2 nodes.

This is the way how I understand it works:
X to scalar: (x,y,z) -> x (the function assigns to a vector its x-component [and doesn't remember that this has once been an x-value])
Y to scalar: (x,y,z) -> y
...

A scalar, that handled xyz seperately would be a vector. Why would we need the concept of a scalar if it was just a special form of vector?

That is correct Nikita. Scalars only remember one component, but if you later feed a scalar into a node that expects a vector (or colour) it will copy the scalar into each of the 3 components.

Matt
Just because milk is white doesn't mean that clouds are made of milk.

#### Volker Harun

##### July 22, 2007, 10:03:58 am #24
You are right, but you are adding two different ordinates not two Xs.

See the attached image that 'if' you delete it will not be a pyramid.

#### Matt

##### July 22, 2007, 10:06:56 am #25 Last Edit: July 22, 2007, 10:10:55 am by Matt
Hi Volker,

This works in TG2 because TG2 conveniently converts vectors into scalars by taking the magnitude of the vector if you don't explicitly specify how that conversion should take place :-)

There is also a function in the Convert menu called "Length to scalar" which does the same thing.

Matt
Just because milk is white doesn't mean that clouds are made of milk.

#### nikita

##### July 22, 2007, 10:14:04 am #26
That explains everything

#### Volker Harun

##### July 22, 2007, 10:22:16 am #27
I had my final exams in maths - it was about vectors in 4-dimensions - I remember now very good, why I almost failed
But I 'd rather like to stop spamming this thread. Again I was just lucky with what I was doing ,-)