Haa Ty Sir!

-k

Hi, title says it all: how can i create ‘true’ color atttribute, i.e. 3 float array with Color..subttype?

When i say ‘true’ color, i mean that when i look geometry spreadsheet, the coloum headers display r, g and b - e.g 'color', 'color' and 'color'.

If I try to do it like this, via wrangle:

v@color = { 1, 0, 0 };

Headers display ''color', 'color' and 'color', but if I do it via Attribute create, and set type to float and Color and size to 3..then headers display r,g and b.

Cheers
-k

Hi Tomas, i guess i kinda was expecting it to place it into template (= grrid) points in both cases. But if this is the way, it just means that when using Copy to points, my source geometry needs to be always in origin. Or, i need to store the sorce geo offset and apply it after Copy to points.

-k

Hi all, i'm trying to get my head around orient attribute, and how to create and use one. And it seems to work nice, until i'm trying to use it with objects that have local translation, i.e. they are not at the center of the world.

If you look at the attached file, teapot_1 has no translation and it is copied where i expected it to be, grid corners/points. But if i use teapot_2, whic have local translation, the result is off as much as the source object is off from the origin.

Is there a way to get around this kind of situation, or is that just another Houdini gotcha…or am i creating the orient attribute totally wrong

Cheers
-k

Hi, i'm trying to render line in mantra so that edges are transparent, and use the ‘free’ space for rotating line a tiny bit. But for some reason the shadow is pointing in the wrong direction.

If you look the attached image, there is a line where edges are treated as transparent. The line is ‘rotated’ (= controlling what part of the uv space is the center) to left. Now, i would assume that the shadow would be rotated to left also…

I'm missing something but what.

Cheers
-k

Is there a way to define the ‘width’ attribute, that Mantre uses when rendering lines, inside shader/material? I tried to export one from shader but Mantra doesn't seem to use it. Only way (so far) that does seem to work is to define it outside shader.

Cheers
-k

Try editing the self, maybe its there

Hi, how can i check if something is connected to subnet input? I'm using Is Connected VOP atm, but the subnet doesn't return anything (= my default value) if nothing is connected

Cheers
-k

Thank You!!! It works Fast test attached. Green color is for front face

Shader/material quickie: is there a way to use “Is Front Face” vop when adding displacement? Currently i have “i” and “n” from surface globals connected to IFF and it works fine. When i try to use returned value with displacement nodes Mantra cries out that the global variable is missing. Displacement globals has “n” but where do i get the required “i”. I'm trying to create a shader for an line that has displacement only on front face.

Cheers
-k

Question about offsetting animation so that animation finishes different time for each object…If you open the attached Houdini file you understand what i mean: a HIP file is more than a 1000 words

I have a box with animation. I scatter some points to grid, and then i copy the box to those points. Each copy i stamp using ‘@ptnum’ expression. Then i use TimeShift SOP with ‘$F-stamp(’../copy1', ‘cf’, 0)' expression.

The question: is there a way to achieve this without TimeShift and stamping?

Cheers
-kimmo

Ndrew Lowell made a tutorisl..short of..about this:
https://vimeo.com/97237290 [vimeo.com]

Camera culling in houdini

Hi all, noob question about particles and velocity/force, and how they are calculated.

I have an animation with 24 frames (1..25), with frame rate 24.

If i have a particle at position 0, 0, 0, and if i apply velocity 1, 1, 0 to it, particle position will be 1, 1, 0 at frame 25.

Now, if i add downward force 0, -1, 0 to it, i would expect that particle position at frame 25 is 1, 0.5, 0. But it's not - it's 1, 0.479167, 0..ish. Am i missing something here, or is this just some kind of rounding error.

If you look at the attached file, initial velocity is add via POP Wrangle (only at frame 1), in order to keep the point at pos 0, 0, 0 in frame 1. If i use Set initial velocity in POP Source, position will not be 1, 1, 0 at frame 24 (?!?!): initial velocity is add in frame 1, whereas velocity from wrangle is add after frame 1.

It doesn't seem to matter which method is used - when the downward force is applied, position is always a bit off. There is probably a very simple solution for this (there usually is) but i don't get it (as usual )

Cheers
-k

Make instance transform..very nice!…but: if i rotate the source geo, it doesn't rotate “arrow” in the desired direction.

If i understood you correctly Tomas, in order to ensure this, i must ensure that the source geo is created/rotated so that it points to Z? I was kinda hoping solution where i don't have to do that - we are in the procedural world after all

-k

Haa - thank you Sir!

Hi, could someone explain me how the N/up combo, or orient attribute works when used in in copy. And how we should use them in order to get expected results

If you look the attached image/scene file, i am trying to copy and align the “arrow” into target point, which have up (yellow) and N (blue..ish) vectors, and i am expecting that the “tip” of the arrow would point the same direction as the N. If i try to use orient, the result is the same.

I am trying to understand this, so that no matter what angle/location the geo is, i can get it to desired position/angle

Drives me crazy - spend almost entire day for this…and i am not any wiser than this morning!

Cheers
-kimmo

Hi, can i use ch VEX function for accessing strings? If you open the attached file, you will notice that i am trying to move one point to a specific location..marked with another point (Demo scene ). I will get the location via opinputpath and point functions. First i will get the path via opinputpath, and then i use it in point method via ch function. Now, it seems that if i use ch function, i will get invalid location. When i use chs, i will get the correct one. Documentation/help says that there is version of ch function that returns string.

What am i missing here?

Cheers
-kimmo

Hmmm..doesn't seem to work

-k

Hi, i was trying to access color (Cd) attribute in POP Force, to move my particles, using ‘$CR’, but it seems that those are not defined. In the old POP network, you could use that i.e. Accelerate node.

What is the ‘correct’ way to use attributes in the new (Houdini >= 15) POP network? I know that i can use POP VOP, but it would be nice to use them in existing nodes.

Cheers

-kimmo

Hi, when i right click in network editor, in Houdini 16, i get the “Tab menu”. When i do the same in Houdini 15, i get options menu - edit parameter interface, match current definition, etc…

Is there a way to return the H15 menu behavior into H16?

Cheers
-k