feat: apply ground friction on predictive velocity correction too - #7
feat: apply ground friction on predictive velocity correction too#7sebcrozet wants to merge 1 commit into
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Noticeable improvement in the 2D examples. The material doesn't seem to slide as on ice, see the screenshots below. Before: After: |
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Hmm, it does look like the fluid example is worse off as the number of escaping particles is increased. I'm not sure why that is. |
Vollkornaffe
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Vollkornaffe
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I think changing the margin from half a grid cell to one-and-a-half is a good idea.
| @@ -125,25 +126,29 @@ fn update_single_cell( | |||
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| if apply_friction { | |||
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This could be a better name
| if apply_friction { | |
| if apply_friction_and_cancel_penetration { |
| let tangent_vel = cell_velocity - normal_vel * normal.into_inner(); | ||
| let tangent_vel_norm = tangent_vel.norm(); | ||
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| let new_normal_vel = normal_vel.max(-dist_with_margin / dt); |
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Even if we zero the normal velocity out completely, particles can still approach the boundary as their non-zero-kernel space goes further. We may want to extend the margin s.t. we cover the whole range of an approaching particle.
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This amounts to changing the line above to let dist_with_margin = (dist - cell_width * 1.5).max(0.0);.
This also restores the previous behavior in the fluid example btw.
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Before this change, ground friction was only applied on grid cells below the ground. Now, just like grid cells below the ground induce a friction impulse proportional to the normal velocity, the grid cells above the ground now apply friction proportional to the removed normal velocity due to the predictive contact.