MFnMesh.setVertexNormal Huge performance issue

[justin hidair]

I made a cool script (just starting in the Python API game)
it works like intend but the problem is speed, therefor performances..

Imagine a set of faces ... why not something like 5984 polygons(=11800 tris)

now imagine you iterate over these faces and for each you get their set of vertex, and within that set you iterate through each vertex to set the normal (With MFnMesh.setVertexNormal() )

like you can imagine that's Reeally quick with a thing like a beveled cube (26 polys)

NOW, how Maya can update its vertex normals on the fly even with huge dense objects, and I get slow, and laggy with simply setting vertex normals???, even though It's not C++
that's not fair ! there must be a way ^_^

[Christopher Crouzet]

MFnMesh.setVertexNormals()?

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Christopher Crouzet
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[Justin Israel]

I don't have much to offer in terms of specifics to the right api calls, but I can imagine 10k python functions calls is insanely slower than 10k C++ calls. 

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[justin hidair]

Using this it'll be faster ? the problem with this one is it requires mvectorArray to be as the same size as the vertex list, while I only have one common normal to apply ... Should I duplicate it time the number of vertices within the list ?

And is there a cool way to duplicate element within a list x number of time in python ?
Also I'm so happy this group exist

[justin hidair]

Le samedi 25 février 2017 01:03:25 UTC-8, Justin Israel a écrit :

I don't have much to offer in terms of specifics to the right api calls, but I can imagine 10k python functions calls is insanely slower than 10k C++ calls. 

What you just said hurt my feelings lol I don't like that

[Justin Israel]

Hah. I'm sorry to be the bearer of bad news. But that benefit you gain in fast prototyping and expressiveness in the dynamic python language is always going to come at a cost. If you are comparing many of thousands of functions calls, attribute accesses, etc, of a dynamically typed interpreted language to a compiled statically typed language, you will find a wide gap. 

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[Michael Boon]

Slower than C++ for sure, but depending on your needs it might still be fine. I often set normals on meshes up to about 100k verts using Python.

To create your MVector array (in Python API 2.0), something like this will do it in less than a millisecond:

    normals = [om.MVector(0,0,1)]*100000

Creating your id list takes about a millisecond too:

    ids = range(100000)

Then, like Christopher said:

    mesh.setVertexNormals(normals, ids)

Trying it on a sphere with 40,000 normals, I can create and set all the normals in 0.03 seconds.

On Saturday, 25 February 2017 20:49:10 UTC+11, Justin Israel wrote:

On Sat, Feb 25, 2017, 10:12 PM justin hidair <justin...@gmail.com> wrote:

Le samedi 25 février 2017 01:03:25 UTC-8, Justin Israel a écrit :

I don't have much to offer in terms of specifics to the right api calls, but I can imagine 10k python functions calls is insanely slower than 10k C++ calls. 

What you just said hurt my feelings lol I don't like that

Hah. I'm sorry to be the bearer of bad news. But that benefit you gain in fast prototyping and expressiveness in the dynamic python language is always going to come at a cost. If you are comparing many of thousands of functions calls, attribute accesses, etc, of a dynamically typed interpreted language to a compiled statically typed language, you will find a wide gap. 

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[justin hidair]

Le dimanche 26 février 2017 15:39:39 UTC-8, Michael Boon a écrit :

Slower than C++ for sure, but depending on your needs it might still be fine. I often set normals on meshes up to about 100k verts using Python.

To create your MVector array (in Python API 2.0), something like this will do it in less than a millisecond:

    normals = [om.MVector(0,0,1)]*100000

Creating your id list takes about a millisecond too:

    ids = range(100000)

Then, like Christopher said:

    mesh.setVertexNormals(normals, ids)

Trying it on a sphere with 40,000 normals, I can create and set all the normals in 0.03 seconds.

Woah , great ! Thank you