Day 49

So again I rendered over night with Wei Jie's shader. The rotation of the sprites were still there.

Through trial and error by offing the effect and render, I managed to find the problem. The problem was caused by the deformed geometry surface which emitted the particles.

simple illustration

The black line is the deformed geometry and the red line is the attribute transfer. So as soon as the geometry cross the red line the particles starts to emit. So surface1 will emit first since it passes the red line first then followed by surface2. So the sprites1 rotates first then the sprites2 rotates. This pattern repeats as there are new particles born. This gives a wavy illusion to the sprites.

So I changed the source of emission from the original impact wave.

not deformed geometry

In this case the sprites would not cause the same effect.

I also decided to change the rotation of the sprites to be rotating inwards the source instead of rotating outwards. 

illustration

Since I couldn't find any videos on aerodynamics references, I drew a example.