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July 12, 2020 19:05
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Minimalist dampened spring using glm
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#ifndef spring_hpp | |
#define spring_hpp | |
#include <glm/glm.hpp> | |
template <glm::length_t L, typename T, glm::qualifier Q = glm::defaultp> | |
class spring_ { | |
public: | |
spring_(T mass, T force, T damping, glm::vec<L, T, Q> zero = {}) | |
: _mass(mass) | |
, _force(force) | |
, _damping(damping) | |
, _target(zero) | |
, _value(zero) | |
, _velocity(zero) | |
, _zero(zero) | |
{ | |
} | |
spring_(const spring_& c) | |
: _target(c._target) | |
, _value(c._value) | |
, _velocity(c._velocity) | |
, _zero(c._zero) | |
, _mass(c._mass) | |
, _force(c._force) | |
, _damping(c._damping) | |
{ | |
} | |
spring_& operator=(const spring_& rhs) | |
{ | |
_mass = rhs._mass; | |
_force = rhs._force; | |
_damping = rhs._damping; | |
_target = rhs._target; | |
_value = rhs._value; | |
_velocity = rhs._velocity; | |
_zero = rhs._zero; | |
return *this; | |
} | |
void setTarget(glm::vec<L, T, Q> target) { _target = target; } | |
glm::vec<L, T, Q> target(void) const { return _target; } | |
void setValue(glm::vec<L, T, Q> v) | |
{ | |
_value = v; | |
_velocity = _zero; | |
} | |
glm::vec<L, T, Q> value(void) const { return _value; } | |
void setVelocity(glm::vec<L, T, Q> vel) { _velocity = vel; } | |
glm::vec<L, T, Q> velocity(void) const { return _velocity; } | |
bool converged(T epsilon = 0.001) const | |
{ | |
return glm::distance(_velocity, 0.0) <= epsilon && glm::distance(_value, _target) <= epsilon; | |
} | |
glm::vec<L, T, Q> step(T deltaT) | |
{ | |
if (deltaT < T(1e-4)) | |
return _value; | |
auto error = _target - _value; | |
auto dampingForce = _damping * _velocity; | |
auto force = (error * _force) - dampingForce; | |
auto acceleration = force / _mass; | |
_velocity += acceleration * deltaT; | |
_value += _velocity * deltaT; | |
return _value; | |
} | |
private: | |
T _mass, _force, _damping; | |
glm::vec<L, T, Q> _target, _value, _velocity, _zero; | |
}; | |
typedef spring_<3, float> spring3; | |
#endif |
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