MayaApi python issue

Coding
1

Hi guys,

I’m trying to get data from fluid shape and stuck on getColors() method.


oFlu = _mapiGetObject( fluidName ) # returns MObject
fnFlu = OpenMayaFX.MFnFluid( oFlu )
        
ptrR = OpenMaya.MScriptUtil().asFloatPtr()
ptrG = OpenMaya.MScriptUtil().asFloatPtr()
ptrB = OpenMaya.MScriptUtil().asFloatPtr()  
        
fnFlu.getColors( ptrR, ptrG, ptrB )

This always returns

Error: TypeError: in method ‘MFnFluid_getColors’, argument 2 of type ‘float *&’

I tried others ways for to produce ‘float *&’, like:

 
import ctypes as ct
ptrR = ct.POINTER(ct.c_float)()

but still does nothing. Could you tell me is this correct way or Maya’s python api just has a bug? Thanks

2

Maybe try initializing the script util object before you create the pointer.


rParam = maya.OpenMaya.MScriptUtil()
rParam.createFromDouble(0.0)
rPtr = rParam.asFloatPtr()

gParam = maya.OpenMaya.MScriptUtil()
gParam.createFromDouble(0.0)
gPtr = gParam.asFloatPtr()

bParam = maya.OpenMaya.MScriptUtil()
bParam.createFromDouble(0.0)
bPtr = bParam.asFloatPtr()

fnFlu.getColors( rPtr, gPtr, bPtr )

maya.OpenMaya.MScriptUtil(rPtr).asFloat()
maya.OpenMaya.MScriptUtil(gPtr).asFloat()
maya.OpenMaya.MScriptUtil(bPtr).asFloat()

But I’ve only used that code in places that work asking for a float &, never a float*&.

You maybe on the right track with ctypes, but you need to create a float array pointer, not just a single float pointer. Also I would recommend initializing it with some values before you pass it to Maya.

Good luck,

Keir

3

You maybe on the right track with ctypes, but you need to create a float array pointer, not just a single float pointer. Also I would recommend initializing it with some values before you pass it to Maya.

Keir, thank you for an advice. I suppose, it must be exactly float *&, because this method returns pointers to internal storage color data of fluid container.

according information from help:

This method returns pointers to the storage for the color data in the fluid.
…
If you modify the data via the pointers returned, you must call the “updateGrid” call or you will not see your changes.

4

This post isveryinformative.*Thank you!