Operating system: Windows 10
Graphics card: GTX1070
Short description of error
If I create a vertex group/weight paint without assigning any faces to it and then use it as a "density" in the vertex groups for particles it still creates particles.
You might not think this is a bug, but together with "Dynamic Paint" it gets to be one.
This because there you can use type "weight" on particles.
In most cases you will then get frames of unused weight paints when particles are not affecting the weight paint.
In those cases there is a leakage of particles in the center of the weight paint, which creates a lot of disturbance in almost all cases when you are trying to do some stuff where you mix weight paint and particles.
Exact steps for others to reproduce the error
You can do this in many ways. I will show two;
Way no 1.
- Create a plane as emitter.
- Create a vertex group on that plane
- Add a particle system to that plane.
- Add the vertex group you created in step 2 to "Density" in "Vertex groups" section for particles.
Run an animation... the particles are coming even if the weight paint now is unused and "blue".
Way no 2 using mask modifier and dynamic paint. "The hard" way.
- Create a plane as an emitter and call it "emitter".
- Create an icosphere called "Particle" and move it a bit so it is away from the plane.
- Now create another plane called "canvas" below the first plane.
- Subdivide "canvas" like 10 times so you get a lot of faces on it.
- Create a vertex group called "MyVertexGroup" on the "Canvas"
- In "Emitter", just create a default particle system.
- Set "render" to object and Instance Object to "Particle"
- Bake it.
- Now add dynamic paint of type "Brush" to the "Emitter" plane.
- Set the brush to "Particlesystem" and select the particlesystem you created
- Select the "Canvas" and do a dynamic paint of type "Canvas" on that one.
- Set Surface type to "Weight", check "Dissolve" and set it to 5 frames and uncheck "Slow".
- Save your .blend file.
- In "Output" of the canvas for the dynamic paint, select the vertex group "MyVertexGroup"
- Run an animation in "Weight paint" mode and see so it works (creates red areas when a particle hits the weight paint)
- Go back to object mode (if 16 works, which it should).
- Select the "Canvas" and add modifier "mask". In mask select vertex group "MyVertexGroup"
- Run animation and see so the mask seems to work.
- Select "Canvas" and create a particlesystem.
- In "Source" for that system, check "Use Modifier stack".
- Run animation.
Now the particles are created when the mask is visible... but if the mask is NOT visible, the particles are still created in the center of the object instead of being "off".
If you use "density" or not on that particlesystem does not matter. Still same behavior.
Can't create particles with the current modifier stack, disable destructive modifiers