48 lines
1.1 KiB
V
48 lines
1.1 KiB
V
module sim
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pub struct SimState {
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mut:
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position Vector3D
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velocity Vector3D
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accel Vector3D
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}
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pub fn new_state(state SimState) SimState {
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return SimState{
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...state
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}
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}
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pub fn (mut state SimState) satisfy_rope_constraint(params SimParams) {
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mut rope_vector := params.get_rope_vector(state)
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rope_vector = rope_vector.scale(params.rope_length / rope_vector.norm())
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state.position = vector(z: params.rope_length) + rope_vector
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}
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pub fn (mut state SimState) increment(delta_t f64, params SimParams) {
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// 1. add up all forces
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// 2. get an accelleration
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// 3. add to velocity
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// 4. ensure rope constraint is satisfied
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// sum up all forces
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forces_sum := params.get_forces_sum(state)
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// get the acceleration
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accel := forces_sum.scale(1.0 / params.bearing_mass)
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state.accel = accel
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// update the velocity
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state.velocity = state.velocity + accel.scale(delta_t)
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// update the position
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state.position = state.position + state.velocity.scale(delta_t)
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// ensure the position satisfies rope constraint
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state.satisfy_rope_constraint(params)
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}
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pub fn (state SimState) done() bool {
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return state.velocity.norm() < 0.05 && state.accel.norm() < 0.01
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}
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