@cyberlecs (Leandro Cavalheiro) posted a new topic, subject "Vertex Weight Proximity Modifier can't affect particles density". It read:

   Hi folks,
    
    Is there a way to control a particle system density falloff based on distance from active camera? It's a concept very similar to LOD.  
    Peter Guthrie (http://www.peterguthrie.net/) describes a similar method to create grass and save rendertimes in this article: http://www.cgrecord.net/2013/11/soa-academy-day-4-diary-part-3.html \- (read paragraph “LIGHTING & MOOD”)  
    I think he uses 3DS Max, but I'm looking for a solution in blender.
    
    As a workaround I'm currently using a weightpaint group to control it but when using multiple cameras its not a cleaver solution. :spin:
    
    Any tips?

So @cyberlecs (Leandro Cavalheiro) replied

    Vertex Weight Proximity Modifier does exactly what I need!
    
    edit:  
    For some unknown reason this modifier have no effect over the Density slot.  
    If I put it over the Length slot it works as expected.  
    Only works over Density slot if I apply the Weight modifier first.
    
    Anyone could confirm if this a default behavior ou it's a bug?

@cyberlecs (Leandro Cavalheiro) replied

    I made a test sample file. Anyone could test it to confirm if this is a bug?
    
    Blender bug trackers are temporarily read-only due to migration, I have to wait to report it.
    
    ### Attachments
    
    VertexWeightProximity_issue.blend (161 KB)

To which @J_the_Ninja (J_the_Ninja) replied

    cyberlecs:
    
    > I made a test sample file. Anyone could test it to confirm if this is a bug?
    > 
    > Blender bug trackers are temporarily read-only due to migration, I have to wait to report it.
    
    Switch on “use modifier stack” in the emission settings, that will have any simulation options take modifiers into account first.
    
    Although I'm a bit confused why length works without it. That's odd.

So @cyberlecs (Leandro Cavalheiro) replied

    Thanks. It works!
    
    But after any change to the modifier, I have to disable and enable again “Use Modifier Stack” button to update particles and see the changes.


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