how can one produce a hex grid in houdini ?

Forums Houdini Indie and Apprentice how can one produce a hex grid in houdini ?

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pheryel: Member; 11 posts; Joined: Sept. 2016; Offline

April 27, 2017 11:43 p.m.

silly question but is there any quick or easy way to make a hexagonal grid in houdini ? would like to make a map based off a system using said grid in order to make a procedural map with more polished peaces to puzzle together.


mestela: Member; 1798 posts; Joined: May 2006; Online

April 28, 2017 11:32 a.m.

there's probably a sweet mathematical way, and my idiot way;

-put down a grid
-divide sop, enable ‘compute dual’
-transform sop rotate 45 degrees around Y
-another transform to scale it along x so the hexagons are symmetrical
-delete in bounds mode to trim it back to a square of hexagons

Attachments:
hexagons.gif (105.7 KB)
hexagons.hipnc (55.5 KB)

http://www.tokeru.com/cgwiki [www.tokeru.com]
https://www.patreon.com/mattestela [www.patreon.com]


anon_user_37409885: Member; 4189 posts; Joined: June 2012; Offline

April 28, 2017 3:30 p.m.

haha nice! I think the platonic soccer ball copied your idea


Konstantin Magnus: Member; 682 posts; Joined: Sept. 2013; Online

April 28, 2017 6:18 p.m.

A rough implementation of a hexgrid algorithm would be connecting two attribwrangles: Set the first one to detail and the second one to run over points.

// Creates a point grid in detail mode
for(int j = 0; j < 10; j++){
    float shift_x = ( (j + 1) % 2 ) * 0.5;
    float shift_z = j * 0.75;
    for(int i = 0; i < 10; i++) {
        vector pos = set(i + shift_x, 0, shift_z);
        addpoint(0, pos);
    }
}

// Draws hexagonal polygons on the grid
int prim = addprim(0, "poly");
float height = (sqrt(3)/2) * 0.5;
float width  = 0.5;
for(int i = 0; i < 6; i++) {
    float angle_deg = 60 * i + 30;
    float angle_rad = $PI / 180 * angle_deg;
    vector pos      = set(@P.x + width * cos(angle_rad), 0, @P.z + height * sin(angle_rad) );
    
    int pt = addpoint(0, pos);
    addvertex(0, prim, pt);
}

If you want to dig a tiny little deeper, here is the source:
http://www.redblobgames.com/grids/hexagons/ [redblobgames.com]
http://www.redblobgames.com/grids/hexagons/implementation.html [redblobgames.com]

Attachments:
hexgrid.jpg (28.5 KB)

https://procegen.konstantinmagnus.de/ [procegen.konstantinmagnus.de]


pheryel: Member; 11 posts; Joined: Sept. 2016; Offline

April 30, 2017 11:13 a.m.

thank you all for the help. was stuck at work last few days. will be trying some of these methods out tonight.


RyuKu: Member; 171 posts; Joined: Oct. 2016; Offline

Nov. 22, 2017 5:19 a.m.

Hey!
Thanks for the examples shown.

@mestela
How you understood that we need to put 0.6 in second transform's x Scale to make polygons symmetrical? Is there a kind of logic in it or you've found that it works by tweaking scale?

@Konstantin Magnus
You have four nodes for this (grid + attribute wrangle + attribute wrangle + null)? I have source grid visible after hexagons are created, you've added some anoter node to delete it, or I did a mistake in code retyping and something there delete grid? Yours hexagons look the same sized on the image uploaded, but how do you know that they are? Is there something in written shows you that it is so? Using what in code you adjust spacing between hexagons?

Thanks for possible replies and advices

Edited by RyuKu - Nov. 22, 2017 06:06:35


mestela: Member; 1798 posts; Joined: May 2006; Online

Nov. 22, 2017 7:23 a.m.

The 0.6 I just got by eyeballing it.

http://www.tokeru.com/cgwiki [www.tokeru.com]
https://www.patreon.com/mattestela [www.patreon.com]


RyuKu: Member; 171 posts; Joined: Oct. 2016; Offline

Nov. 22, 2017 1:37 p.m.

@mestela Thanks


Konstantin Magnus: Member; 682 posts; Joined: Sept. 2013; Online

Nov. 22, 2017 7:27 p.m.

Hi Ryu,

Ryu Ku
You have four nodes for this (grid + attribute wrangle + attribute wrangle + null)?

No, just two wrangles (see attachment).

Ryu Ku
Using what in code you adjust spacing between hexagons?

Multiply the same value on height and width.

Attachments:
hexagons.hipnc (70.9 KB)

https://procegen.konstantinmagnus.de/ [procegen.konstantinmagnus.de]


RyuKu: Member; 171 posts; Joined: Oct. 2016; Offline

Nov. 23, 2017 2:59 a.m.

@Konstantin Magnus
Couldn't imagine that we don't need grid object for this. Now it's clear. With width and height too. Thanks


vusta: Member; 555 posts; Joined: Feb. 2017; Offline

Nov. 24, 2017 2:28 a.m.

so here's my way…it boils down to divide and conquer…or translated to: create a unit of something, clone it, offset it, radial clone it…whatever….it's just cloning…

I'm not a coder so cannot cram things into one wrangle…but for other non-programming ppl out there..you can look at my files here:

https://www.facebook.com/groups/HoudiniArtists/permalink/1467625033353296/ [www.facebook.com]

step-by-step are pretty easy to understand…it's just cloning, offsetting…

(oh yes…mine produces points…so technically not a grid)

Edited by vusta - Nov. 24, 2017 02:37:16


RyuKu: Member; 171 posts; Joined: Oct. 2016; Offline

Nov. 24, 2017 3:10 a.m.

@vusta If you're talking about hex grid example, would be nice if you'll upload it here, interested to look in , but I don't have Facebook account


anon_user_89151269: Member; 1755 posts; Joined: March 2014; Offline

Nov. 24, 2017 4:59 a.m.

Cool!
Mestela's approach shows how a bit of node-fu and creativity can quickly take you out of a ditch.
Konstantin's vex method is the preferable one if you want your hexagons to be “perfect”.
Thanks for sharing these guys!

Edited by anon_user_89151269 - Nov. 24, 2017 04:59:48


vusta: Member; 555 posts; Joined: Feb. 2017; Offline

Nov. 24, 2017 5:52 a.m.

Ryu Ku
@vusta If you're talking about hex grid example, would be nice if you'll upload it here, interested to look in , but I don't have Facebook account

Edited by vusta - Nov. 24, 2017 06:03:18

Attachments:
vu_honeycomb_02.hipnc (105.5 KB)


RyuKu: Member; 171 posts; Joined: Oct. 2016; Offline

Nov. 24, 2017 1:19 p.m.

@vusta
Very interesting approach to create hexagon, you've reminded me that I need to find out how to work with For-Each Loops still don't know it

Changed you packing tube to six Columns, like the effect it gives and like how you've called the file, didn't think about miel before it relatively to hexagons

Thanks for the example

Edited by RyuKu - Nov. 24, 2017 13:20:51


Schmauch: Member; 21 posts; Joined: Aug. 2014; Offline

May 4, 2018 2 p.m.

I tried to replicate the code of Konstantin Magnus and the hex was always squished a bit. What gave me an regular hex was this. Took me some time to figure out because I don´t know my way around math very well. Perhaps it can be of help to someone.

@Konstantin Magnus Thanks for the starting point and the wonderful Red Blob Games [www.redblobgames.com] link

int prim = addprim(0, "poly");
float size = 0.5;
for(int i = 0; i < 6; i++) {
    float angle_deg = 60 * i-30;
    float angle_rad = $PI / 180 * angle_deg;
    vector pos      = set(@P.x + size * cos(angle_rad), 0, @P.z + size * sin(angle_rad) );
    
    int pt = addpoint(0, pos);
    addvertex(0, prim, pt);
}


BabaJ: Member; 2127 posts; Joined: Sept. 2015; Offline

May 4, 2018 9:35 p.m.

Saw this post a while back and wanted to give it a whirl but didn't have the time…had time today.

I seperated the hexagons into two vex nodes - one for just creating the hexagons points (their hex “corners”).

And the second to make them into polylines or polygons.

The third node is an add node just to quickly create the polygons by attribute ( in this case the hex number ).

Both vex nodes have a folder tab with control paramters.

The first vex node name “Create Hexagon Points” has the following controls:

* Hexagon starting point
* Hexagon Radius
* Number of Hexagons per row
* Number of Rows

The second vex node has the parameter to switch back between polys or polylines.

Edited by BabaJ - May 4, 2018 21:37:47

Attachments:
Hexagons.hiplc (80.1 KB)


Konstantin Magnus: Member; 682 posts; Joined: Sept. 2013; Online

May 5, 2018 3:39 a.m.

A non-mathematical approach would be

a grid with alternating triangles,
grouping its crossing points,
scaling it by ~1.7 along X,
and copying six sided circles on them.
A fuse will cover tiny imprecisions.

Attachments:
hex_grid.hipnc (72.3 KB)

https://procegen.konstantinmagnus.de/ [procegen.konstantinmagnus.de]


Nick Wood: Member; 1 posts; Joined: April 2015; Offline

May 19, 2018 4:40 p.m.

Because there's always room for more methods?

Here's a super simple solution based on a tetrahedral Points From Volume SOP.

There used to be more here, until I realised that I didn't need most of what I'd put down. Delete delete delete…

Edited by Nick Wood - May 23, 2018 11:32:16

Attachments:
hex grid 2.hiplc (209.3 KB)


STEVLTH: Member; 1 posts; Joined: Sept. 2018; Offline

March 31, 2019 3:51 p.m.

Thanks to everyone for your methods. I made my own super simple method, that converts the default grid to hexagonal grid using ‘pointsfromvolume’ node with Tetrahedral point configuration.
You can easily control grid size, hexagon size (Point separation in the ‘pointsfromvolume’ and hexagon offset (circle radius).

Attachments:
hex_grid_STEVLTH_edition.hipnc (110.8 KB)

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