explicit.py

scene = 1

if __name__ == "__main__":
    if scene == 1:
        from scene1 import *
    elif scene == 2:
        from scene2 import *

    @ti.kernel
    def substep():
        # Compute force and new velocity
        n = num_particles[None]
        for i in range(n):
            total_force = ti.Vector(gravity) * particle_mass
            for j in range(n):
                if rest_length[i, j] != 0:
                    x_ij = x[i] - x[j]
                    v_ij = v[i] - v[j]
                    total_force += -damping[None] * x_ij.normalized() * v_ij * x_ij.normalized()  # damping
                    total_force += -spring_stiffness[None] * (x_ij.norm() - rest_length[i, j]) * x_ij.normalized()  # spring
            v[i] += dt * total_force / particle_mass


    init_mass_spring_system()

    while True:
        process_input()

        if not paused[None]:
            for step in range(10):
                substep()
                update_position()
                collide_with_ground()
                compute_damp_energy()
            compute_current_energy()
        process_output()