MaxToHou | Creating peeling/cracked paint [using image to ontrol geom

[MichaelK]

Hello od|forum!

 

I am (very) slowly transitioning from Max to Houdini as I see no future with Autodesk.

I am trying to recreate Max-workflows in Houdini (or rather trying to understand how Houdini works)

 

Can someone here help me translate the following?

 

I am trying to achieve a torn/cracked mesh effect on a cylinder (a geometric one, no alpha map trickery)

 

 

 

 

 

create mesh with UVs

draw high resolution black/white texture map in Photoshop (like an alpha map)

 

 

in 3ds max:

 

Cylindrical low poly mesh with UVs

 

>>  Turbosmooth Modifier (subdivide)

>>  Vol.Select Modifier by b/w texture map (select vertices or polygons via texture map)

>> MeshSmooth Modifier (subdivide selected area only)

>> Vol.Select by same texture map

>> MeshSmooth selected area again (increasing polycount only in areas where it's needed)

>> Vol. Select by same texture map

>> DeleteMesh modifier

 

...with maxscript  >> Automatically select all boundary edges

 

>> Edit Poly / Soft Selection + Grow Selection

>> Mesh Select

>> Noise Modifier (randomly displace selected/cracked edges)

 

 

If I prepare a new custom texture map I will have the parametric setup to generate new "cracked" geometry.

 

Thank you for reading.

 

Cheers

Michael

[Yader]

You could utilize the Attribute from Map Sop to get your map colors onto your mesh,

followed by a group node with the Operation set to Group by Expression with something

like @Cd<0.1 to select all darker tones of your point colors, after that subdivide with the group you just created,

repeat as much as you like, you can use the expression above in a delete sop as well.

In the group sop there's also an option, which when you select Edges as Entity allows to

select just the unshared edges.

Edited February 8, 2016 by Yader

[konstantin magnus]

here is an example. i would not use local subdivision hence the switch.

paint.hipnc

Edited February 9, 2016 by konstantin magnus

[MichaelK]

Hello Yader and hello Konstantin!!

 

thank you for the swift reply, for your insightful answers and example file, but ....oh boy....

...I am humbly and slowly crawling through Konstantin's SOP + VOP network and experimenting with the values and txtrmap in order to understand it.

 

And I am yet to recreate Yader's suggestion.

@Yader, when you say Map SOP do you mean Attribute from Map?

 

@Konstantin, why wouldn't you use local subdivision? Isn't it less taxing for the computer?

 

I'll get back to it!

 

Cheers guys and thank you!

Michael

[Yader]

Attached is a file with a some of the sops you could use for your setup. 

Just replace the image in the attribute from map sop with yours.

Peeling_Paint_02.hipnc

Edited February 10, 2016 by Yader

[konstantin magnus]

@michaelk: i think you get a cleaner mesh using all regular quads. also you can still use "polyreduce" afterwards if you want to save polygons.

VOPs can run through all points in no time while creating groups for certain polygons and looping them through "for each"-sops may get costly indeed.

 

Maybe you can learn some from this, too:

Edited February 10, 2016 by konstantin magnus

[MichaelK]

Hello Yader and Konstantin!


@Yader
Thank you for your .hipnc file.
I have been trying to modify the node setup a little bit. Unfortunately, I am having a hard time reproducing the simplest things like
creating a soft/smooth selection from the group-SOP "selection" (from the Cd attribute..)
I searched the forums, tried softTransform-SOP, attribute transfer + smooth SOP, etc. ..to no avail.


How does one "convert"/modify the group-SOP selection to a soft selection/ selection with falloff for further use down the chain?


@Konstantin
In your file there is a peel_shape node and a displacement node inside the attribute vop (pointvop1), but , interestingly,
I am not able to manipulate any of the peel shapes by changing values within those nodes. The mountain SOPs however, do exactly that.
You do you use vecgetcompon, ramp and perhaps compare in your tutorial as well to create the bulge, but I fail to see what exactly it does in the vop node.
Your tutorial on how to model a shampoo bottle shows a very elegant and nifty approach. It is however, at the moment,
way too advanced for me. I will have to tackle expressions and VOP nodes step by step and hopefully soon I will have caught up
with your train of thought.


Thank you guys!

Cheers
Michael
 

[konstantin magnus]

it should be possible to manipulate these values one level above (when you dont dive into the vop node, you can just check its own parameters).

 

try kim goossens tutorials on procedural modeling:

https://www.youtube.com/playlist?list=PLShEm1_z6_cyBOAKQSH2ck-enGSnovMjD

 

i think with houdini tutorials you should not expect to fully understand them right away ; ) it may take some repetitions here and there.

Edited February 13, 2016 by konstantin magnus

[MichaelK]

it should be possible to manipulate these values one level above (when you dont dive into the vop node, you can just check its own parameters).

 

try kim goossens tutorials on procedural modeling:

https://www.youtube.com/playlist?list=PLShEm1_z6_cyBOAKQSH2ck-enGSnovMjD

 

i think with houdini tutorials you should not expect to fully understand them right away ; ) it may take some repetitions here and there.

 

Yes it is possible in the mountainSOPs.

I am still dissecting and scrutinizing your vop node (and those in your tutorial) since the changes I make to it do not produce any visible effects.. :-)