Particles render inconsistently without dynamic parameter module, when the dynamic parameter node is in their material

Submitted this using the bug report submission page. Posting here in case anyone else runs into this problem, I’ll update with a tracking number if the bug is accepted.

  1. Create a new blank project.

  2. Create a new material (M_DynamicParameter).

  3. Set M_DynamicParameter to a Translucent blend mode.

  4. Add a 3Vector and set it to R:1, G:0, B:0.

  5. Connect 3Vector into base color.

  6. Add a RadialGradientExponential node.

  7. Add a DynamicParameter node.

  8. Give the first pin a name of FadeOut.

  9. Add a multiply node.

  10. Connect the output of the RadialGradientExponential to the A input of the multiply node.

  11. Connect the output of the FadeOut pin from the Dynamic Parameter to the B input of the multiply node.

  12. Apply changes to M_DynamicParameter.

  13. Create a new particle system (P_DynamicParameter).

  14. Set the material of the default emitter in P_DynamicParameter to use M_DynamicParameter.

The particles will only display the proper transparency once every several particles spawned. View in wireframe to confirm that the same amount of particles being spawned, but not all of them display.

After viewing result:

  1. Add a DynamicParameter module.
  2. Review P_DynamicParamter. Now all the particles display and they all have the same transparency.

This behavior is new to 4.19, tested in 4.18 using the same steps and there is no difference between the particles whether the Dynamic Parameter module is on the emitter or not.

Reused materials don’t always need the same fine control, so it would be nice to not have to add the Dynamic Parameter module if the controls aren’t needed for that specific emitter. It would also be awesome to not have to go back through and add the module to all the emitters in all the particle systems that use that material :confused:


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Thanks, I was going crazy not knowing why only 1 particle was rendering at a time. I added the Dynamic Parameter module to the emitter and they all render now. I hope they fix this so it is the way it was before!