I have set up an animation of a quite large particle system (over 50,000 particles). The Rendered Shade Mode is quite heavy so I prefer to use Render > OpenGL Render Animation. Camera animation is out of question in such a scenario. However, I am in need of showing around the object emitting the particles and the only solution, in this case, is to rotate the object itself. The problem is that the physics animation doesn't keep track of the rotation of the emitter. Once the emitter is rotated, the physics animation continues as if the object was in its initial position.

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    $\begingroup$ Easiest solution will be to move the camera rather than rotate the object. Why do you think animating the camera is out of the question? $\endgroup$ – Rich Sedman Mar 24 '18 at 23:39
  • $\begingroup$ Following your comment, I must change the question to "Does OpenGL Render Animation allow camera animation" ? As an inexperienced user, my answer is "No". $\endgroup$ – Kar Mar 25 '18 at 8:16
  • $\begingroup$ Yes - the Render/OpenGL Render Animation renders from the point of view of the camera, in the same way as for a ‘full’ render. This is effectively the same as what you see in the 3D View when locked to the camera (Numpad 0). $\endgroup$ – Rich Sedman Mar 25 '18 at 10:28
  • $\begingroup$ Indeed you are right. By the way, due to the same memory-related issues mentioned in the original post that led me to opt for OpenGL Render Animation, I have another problem regarding the fact that it seems impossible to hide the emitter and particle system individually though they both feature the "eye icon" in the outliner. The option not to show the emitter given in the particle system panel is only useful in case of a full shade mode rendering. $\endgroup$ – Kar Apr 4 '18 at 17:23

One part of the problem - i.e. OpenGL-rendering an emitter and its particle system being spatially transformed at a definite keyframe of a physics animation - was solved thanks to Rich Sedman comment about locking the 3D View to the camera (Numpad 0). Yet, I also had two additional constraints:

  • make the physics animation as short as possible in an orthographic view and rely on its end (physics) state to produce a panoramic view of the particle system;
  • hide the emitter and leave the particle system alone while panoramically showing around the last frame of the physics animation;

To reach these goals, the particle animation render (Particle System ‣ Render) was chosen of type Object (or Group of objects) with a (small) UV sphere in place of each particle. In the Display panel of the emitter, I had to switch the Maximum Draw Type from Wire to Solid though Wire was enough for my purpose of showing the (haloed) particle system alone but with Object as render type it ran into the pitfall of drawing the edges of each single sphere. So, I had to rely on Transparency which had to be checked off in the same Display panel to enable the alpha channel of emitter Viewport Color set to 0 (Cycles Render). Having run and baked the animation and selected its end frame, pink vertex (I would like to generate a particle star field that I could keep as static background) provided a super script which allowed to supersede the particles with a real mesh of point-vertices. Then, using the DupliVerts technique (Object panel ‣ Duplication ‣ Vertices), a copy of the (small) sphere chosen for the physics animation render was used to replace each point-vertex. From this point forward, it was just a matter of making up the animation through the Dope Sheet (Action Editor) applying Restrict View / Restrict Render keyframes to show the original particle system for the actual duration of the physics animation and keep the duplicated one hidden at the same time. On the contrary, during the part of the animation which was not physically baked, the duplicated system was visible while the camera moved around and the original particle system was hidden.

  • $\begingroup$ I found a completely haloed version is possible with the same rationale of the object-in-place version described above. Just create a new particle system for the duplicated mesh of point-vertices and Emit From Verts. Change Emission Start and End to the value of the end frame of the physics animation. $\endgroup$ – Kar Apr 9 '18 at 9:39

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