v/examples/pendulum-simulation/modules/sim/params.v

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module sim
import math
pub const (
default_rope_length = 0.25
default_bearing_mass = 0.03
default_magnet_spacing = 0.05
default_magnet_height = 0.03
default_magnet_strength = 10.0
default_gravity = 4.9
)
[params]
pub struct SimParams {
rope_length f64 = sim.default_rope_length
bearing_mass f64 = sim.default_bearing_mass
magnet_spacing f64 = sim.default_magnet_spacing
magnet_height f64 = sim.default_magnet_height
magnet_strength f64 = sim.default_magnet_strength
gravity f64 = sim.default_gravity
}
pub fn sim_params(params SimParams) SimParams {
return SimParams{
...params
}
}
pub fn (params SimParams) get_rope_vector(state SimState) Vector3D {
rope_origin := vector(z: params.rope_length)
return state.position + rope_origin.scale(-1)
}
pub fn (params SimParams) get_forces_sum(state SimState) Vector3D {
// force due to gravity
f_gravity := params.get_grav_force(state)
// force due to magnets
f_magnet1 := params.get_magnet1_force(state)
f_magnet2 := params.get_magnet2_force(state)
f_magnet3 := params.get_magnet3_force(state)
mut f_passive := vector(x: 0.0, y: 0.0, z: 0.0)
for force in [f_gravity, f_magnet1, f_magnet2, f_magnet3] {
f_passive = f_passive + force
}
// force due to tension of the rope
f_tension := params.get_tension_force(state, f_passive)
return f_passive + f_tension
}
pub fn (params SimParams) get_grav_force(state SimState) Vector3D {
return vector(z: -params.bearing_mass * params.gravity)
}
pub fn (params SimParams) get_magnet_position(theta f64) Vector3D {
return vector(
x: math.cos(theta) * params.magnet_spacing
y: math.sin(theta) * params.magnet_spacing
z: -params.magnet_height
)
}
pub fn (params SimParams) get_magnet_force(theta f64, state SimState) Vector3D {
magnet_position := params.get_magnet_position(theta)
mut diff := magnet_position + state.position.scale(-1)
distance_squared := diff.norm_squared()
diff = diff.scale(1.0 / math.sqrt(distance_squared))
return diff.scale(params.magnet_strength / distance_squared)
}
pub fn (params SimParams) get_magnet_dist(theta f64, state SimState) f64 {
return (params.get_magnet_position(theta) + state.position.scale(-1)).norm()
}
pub fn (params SimParams) get_magnet1_force(state SimState) Vector3D {
return params.get_magnet_force(0.0 * math.pi / 3.0, state)
}
pub fn (params SimParams) get_magnet2_force(state SimState) Vector3D {
return params.get_magnet_force(2.0 * math.pi / 3.0, state)
}
pub fn (params SimParams) get_magnet3_force(state SimState) Vector3D {
return params.get_magnet_force(4.0 * math.pi / 3.0, state)
}
pub fn (params SimParams) get_tension_force(state SimState, f_passive Vector3D) Vector3D {
rope_vector := params.get_rope_vector(state)
rope_vector_norm := rope_vector.scale(1.0 / rope_vector.norm())
return rope_vector_norm.scale(-1.0 * (rope_vector_norm * f_passive))
}