How To Refresh A Custom Shading Node?

[ahimsa]

Hi, I'm writing a plugin which is registered as "texture/2d".
It draws something onto the texture, using the "compute" method.

The problem is, "compute" is called only once when "myShader" is created via Hypershade (which executes "shadingNode -asTexture myShader;" internally).

Is there any way to FORCE Maya to refresh the shading node so it can re-compute the texture?
I tried "refresh -f;" in the script editor, nothing happened.

I need this because the content of the texture is animating (changes in time) and needs to be refreshed.

Besides, how can I make the "Output Window" show up?
I called "cout" many times for debugging, but never can see anything!

[codebox]class myShader : public MPxHwShaderNode
{
...
virtual MStatus compute(const MPlug&, MDataBlock&);
...
}

MStatus myShader::compute(const MPlug& plug, MDataBlock& block )
{
// Draw something!
}[/codebox]

[joojaa]

Your shader needs to declare a affect network so you must tell maya at node crateion what input affects what output thisway maya will magically know to do it.

The update of textures suring playback is intentionally suspended because its so heavy a operation.

QUOTE
Besides, how can I make the "Output Window" show up?

render something, ususally the problem is rather how to get rid of the window. Doe not bother me but bothers some.

Anyway it should be open when you start maya dont kill it just minimize it.

[plipson]

I've got a similar problem - I've got an MpxHwShaderNode built around the ATI AshliShader sample. I've added some ability to control the global environment (affecting all instances of the shaders), and added some semantic definitions to introduce special values into my shader code.
But when I use a command to change these parameters, I need to have glBind called on all the nodes. Unless I set some attribute in each node, or change the view (scrolling it, or even forcing a change in window focus) I don't get that call to happen.
There's got to be some simple "setDirty" call that I can use. This is a bit different than typical DG node update issues, though, since I don't -think- that the compute() function is directly related to the rendering traversal (what the white paper on HWShaders calls the "refresh architecture".

any thoughts?

[joojaa]

Yes you can use the mel command dgDirty. Its for debufgging so if you sue it you are in the gary land of doing hacks. (also you can iterate all the plugs and set them dirty read docs on mPlug but thats basically what dgdirty does)

Whats wrong with having a extra attribute (it doent tax you NEARLY as much as uppdating them all dirty) Just mark the connection as auxilliary and no one knows it there. I suggest you use a set as basis for the connector. Then assign all your affetees to that set and update something in the set. (also elegant for man other things)