Unfortunately I was able to pretty easily break this system :(
While playing around with all kinds of edits, I noticed that when I had
Material1 assigned to my object the hierarchical eval id was 20 less than
when I had Material2 assigned. I also noticed that if the object had a
bend modifier on it, changing the bend angle would increment the
hierarchical eval id by 2. So with this sequence of events, I got the same
eval id before and after edits.
*Hierarchical eval id of the sphere is shown in brackets at each step*
Start: sphere with bend modifier, Material2 assigned (226)
Assign material 1 (206)
Change the bend angle 10 times (226)
The problem is the way the hierarchical eval id is computed by simply
summing the eval ids up the hierarchy. Maybe instead, I could crawl the
hierarchy myself (annoying but not a big deal) and compute a hash from all
eval ids in the hierarchy of the object. Assuming a suitable hash
function, any change to any eval id in the hierarchy would cause big
changes in the hash and bring the probability of a false negative down to
some infinitesimally small amount.
On Fri, May 4, 2012 at 6:12 PM, Nicolas Burtnyk <nico...@redshift3d.com>wrote:
> To Steven : if the application of the shader to the object creates a
> shader and a material and connects the shader to the material, then yeah,
> those events are called. But if you assign an existing material, they're
> not.
>
> To Jo: I'm playing with this right now and it's very promising. I wonder
> though if it's possible to get the same hierarchical evaluation id after
> some edits. The reason I'm worried about this is that I noticed that
> assigning different materials to an object caused the hierarchical
> evaluation id to go up and down. I wonder if some combination of edits
> could result in the same evaluation id and therefore cause my system to
> think nothing has changed which would obviously be pretty bad! Other than
> this worry, and verifying that this is valid for all kinds of edits that
> might change the way an object is rendered, this technique of checking the
> hierarchical object id might be a lot simpler than chasing down every last
> little command, callback, etc.. that can change the scene.
>
> Thanks guys!!
>
>
> On Fri, May 4, 2012 at 6:02 PM, Steven Caron <car...@gmail.com> wrote:
>
>> in my quick test i applied multiple shader's from the menu, both standard
>> and custom. both seemed to get fired. i could have been wrong.
>>
>>
>> On Fri, May 4, 2012 at 5:20 PM, Nicolas Burtnyk
>> <nico...@redshift3d.com>wrote:
>>
>>> Thanks Steven!
>>>
>>> I already use siOnConnectShader (and siOnDisconnectShader) to track
>>> changes to the shader tree. These don't get fired as a result of assigning
>>> a material to an object. siOnCreateShader only gets called when you create
>>> a shader node and in fact partially fails at even that since it doesn't get
>>> called when you create a material (which creates a shader as well).
>>>
>>> Thanks for the tip on material assignment via drag & drop. Kind of a
>>> shame that it ends up calling CopyPaste command but it should be simple
>>> enough to monitor for that command as well.
>>>
>>> -Nicolas
>>>
>>>
>>>
>>> On Fri, May 4, 2012 at 4:54 PM, Steven Caron <car...@gmail.com> wrote:
>>>
>>>> have you tried... siOnCreateShader? i generated this event from the
>>>> wizard and it seems to log a lot of relevant info. also there is
>>>> siOnConnectShader
>>>>
>>>> " *Question*: Can material assignment happen without this command
>>>> being run? In other words, is catching this command sufficient for
>>>> monitoring all the ways that a material can be assigned to an object? I'm
>>>> not very experienced with using Softimage, but I know that in Maya there
>>>> are a million and one ways to assign materials. "
>>>>
>>>> -one could change the shader graph but not the material assignment.
>>>> -one could 'drag and drop' a material from the material view in the
>>>> explorer on to an object. that calls 'CopyPaste()' command. i have always
>>>> been on the fence whether that command is good or bad)
>>>>
>>>>
>>>> On Fri, May 4, 2012 at 4:39 PM, Nicolas Burtnyk <nico...@redshift3d.com
>>>> > wrote:
>>>>
>>>>> Hi list people!
>>>>>
>>>>> For my custom renderer, I'm trying to keep track of when materials get
>>>>> assigned to objects.
>>>>> This is part of an overall system which tracks changes to the scene so
>>>>> that I can incrementally process only the parts of the scene that change
>>>>> between renders.
>>>>>
>>>>> Since there is no specific event that gets fired when a material is
>>>>> assigned to an object (that I know of - please correct me if I'm wrong!),
>>>>> I'm trying to use *siOnEndCommand *to catch the *AssignMaterial *command.
>>>>> *By the way Softimage devs: please add a OnMaterialAssigned event :)*
>>>>>
>>>>> I have 1 question and 1 issue:
>>>>>
>>>>> *Question*: Can material assignment happen without this command being
>>>>> run? In other words, is catching this command sufficient for monitoring
>>>>> all the ways that a material can be assigned to an object? I'm not very
>>>>> experienced with using Softimage, but I know that in Maya there are a
>>>>> million and one ways to assign materials.
>>>>>
>>>>> *Issue*: While I'm correctly receiving the ApplyMaterial command in
>>>>> the siOnEndCommand callback, I'm having trouble deciphering the command
>>>>> arguments.
>>>>> Basically I want to know the Material that was assigned and the
>>>>> Object(s) it was assigned to. Simple, right?
>>>>> In the siOnEndCommand callback, I get the "Command" attribute from the
>>>>> context and create a Command object from it. I then retreive the
>>>>> arguments
>>>>> using Command::GetArguments(). The ArgumentArray always has a count of 2
>>>>> (whether I assign the material to 1 or more objects).
>>>>> The second argument (ActionWhenLocalMaterialsOverlap) is irrelevant to
>>>>> me. The first argument is a CValueArray that has a CRef for the Material
>>>>> being assigned as its first element and some mysterious CRef as its second
>>>>> item. *My issue is that I don't know what to do with this strange
>>>>> CRef*.
>>>>>
>>>>> Here is a concrete example:
>>>>>
>>>>> I have 2 objects and 1 material in my scene and assign the material to
>>>>> both objects in a single action:
>>>>> Application.AssignMaterial("Sources.Materials.DefaultLib.Material,sphere,cylinder",
>>>>> "siLetLocalMaterialsOverlap")
>>>>>
>>>>> In the siOnEndCommand callback I get:
>>>>>
>>>>> Command(Context(in_ctxt).GetAttribute(L"Command")).GetArguments()[0].GetValue()returns
>>>>> a CValueArray with 2 items.
>>>>>
>>>>> Item 0 : CValue, m_t=siRef - this is a CRef to the Material being
>>>>> assigned, as expected. GetAsText() return
>>>>> "Sources.Materials.DefaultLib.Material" and GetClassIDName() returns
>>>>> "Material". Good to go.
>>>>>
>>>>> Item 1 : CValue, m_t=siRef - this is some kind of weird CRef that I
>>>>> don't know how to handle. GetAsText() returns "sphere,cylinder" and
>>>>> GetClassIDName() returns "Object". What do I do now? How can I get those
>>>>> objects as CRefs? Do I have to tokenize the string and parse out the
>>>>> object names? It's not hard, but I'd like to do something cleaner if
>>>>> possible.
>>>>>
>>>>> Thanks!!
>>>>>
>>>>> -Nicolas
>>>>>
>>>>
>>>>
>>>
>>
>
