Hi guys

I`m new to Houdini and I had no problem understanding the principle of operation of the "For Each" nodes, more or less figured out most operations on vectors and other topics that some beginners having hard time understanding. But I unexpectedly completely stuck on "Object Merge" node in transform mode: "INTO SPECIFIC OBJECT". And I don't understand what's going on there at all, and most importantly, what its mode purpose.

For example we have two OBJ level nodes, one with a sphere and other one with the box inside. We create a object_merge node near the sphere node and choose the box to be copied inside inside the OBJ node where we already got the sphere.

- If you choose transform : "None" - it just copies the box object into the origin of our "sphere" OBJ node. Just where the sphere is. And its all understood.
- If you choose transform : "Into this object" - It copies the box into our "sphere" OBJ node but now its moved relative to its origin so it remans on same place as original box in global coordinates. Also if we move the sphere it "compensates" by moving the box points (or we can call it locally transforms it) in opposite direction so it will remain on same place globally. And its also understood.
- If you choose transform : "Into specific object" - Which is randomly placed null object in my case - pure chaos starts for me - I though it would copy the box to the coordinates of that "specific object" but it does not. Instead it copies the box to some weird coordinate for some reason, and when I move the sphere - it moves the box with it but when I move the "specific object" it starts to move the box simultaneously but in inverted direction. I think it tries to "compensate" the movement of that null (just like it did for sphere in 2 mode but now sphere is not moving so box should go in opposite direction) or something but what for ? And why sphere is not moving with the box in that case what purpose of that ?

So my main question is - what this weird looking transform tool is made for and why it behaves so strangely ? Why do I need that box moving in opposite direction. I`m sure there is some useful application for this or at least clear logic which I just do get.

Thank you


P.S : If someone would like to see the setup its attached or you can see it in one tutorial vid below where guys are explaining that node (failed for me).

https://www.youtube.com/watch?v=P2LKBOQnjYQ [www.youtube.com]

Object Merge will take geometry from local space of the Cube, optionally applies Transform and brings it into local space of the Sphere

so you can think about those transform modes in terms of what transform is added to the geo you are merging into your sphere and then obviously separate Sphere's object level transform will also be applied, since that geo lives within the sphere


None - will not apply any additional transform
Into This Object - a delta transform from Sphere to Cube is applied
Transform Into Specific Object - a delta transform from Reference Object to Cube is applied

which in other words means that the transform delta of the Cube geometry from the Sphere Object will be the same as transform delta of the Cube Object from the Reference Object

this can be useful if you have a hierarchy of Objects and you want to merge all of them into another Object relative to their Root Object for example

tamte
Object Merge will take geometry from local space of the Cube, optionally applies Transform and brings it into local space of the Sphere

so you can think about those transform modes in terms of what transform is added to the geo you are merging into your sphere and then obviously separate Sphere's object level transform will also be applied, since that geo lives within the sphere


None - will not apply any additional transform
Into This Object - a delta transform from Sphere to Cube is applied
Transform Into Specific Object - a delta transform from Reference Object to Cube is applied

which in other words means that the transform delta of the Cube geometry from the Sphere Object will be the same as transform delta of the Cube Object from the Reference Object

this can be useful if you have a hierarchy of Objects and you want to merge all of them into another Object relative to their Root Object for example

Yes, the DELTA indeed. Now its more clear. Thanx.