github(第一次用 ) https://github.com/hakic/GAME201_HW1

把大部分 **README.md**复制过来

Implemented explicit and implicit euler of **mass spring** .

Explicit euler, implemented

- Forward euler
- RK2
- RK3
- RK4

Implicit euler, implemented

- Backward euler with jacobi iteration (#iteration=20)

More details:

- Code was based on
**mass_spring_explicit.py**example. - Moved “Collide with ground” to after “Compute new position” because my explicit code updates
*x*and*v*at the same time (I didn’t know whether this was acceptable or not) - Didn’t know how to compute gradient in implicit euler. Used auto-grad in
**taichi**to compute the gradient. - Settings:
- #particles = 10
- damping = 20.0
- dt = 1e-3

Comparsion

表格复制有格式问题，请前往github查看

## Observation

- When damping exists, energy stableness of implicit euler is better; otherwise, all methods are great.
- When damping exists, all simulation looks similar; otherwise, all looks different (please check the following GIFs)
- RK3 / RK4 / implicit euler provide good max spring stiffness.
- Implicit euler provides much better max dt.