66 lines
1.7 KiB
C
66 lines
1.7 KiB
C
#ifndef OVM_PHYSICS_H
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#define OVM_PHYSICS_H
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#include "base.h"
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#include <math.h>
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#define G 6.67428e-11
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#define Me 6.0e24
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#define Re 6.357e6
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typedef struct {
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gdouble x, y;
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} vector_t;
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typedef struct {
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vector_t g, v;
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gdouble v_abs;
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} move_data_t;
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typedef struct {
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vector_t pos_old, pos;
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gdouble rad2_old, rad_old, rad2, rad;
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vector_t dv_old, dv;
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gboolean b_old, b; /* whether the following was calculated */
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move_data_t move_old, move;
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} satellite_t;
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static inline void satellite_update_pos(satellite_t *s, gdouble x, gdouble y) {
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s->pos_old = s->pos;
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s->rad2_old = s->rad2;
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s->rad_old = s->rad;
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s->dv_old = s->dv;
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s->b_old = s->b;
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s->move_old = s->move;
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s->pos.x = x; s->pos.y = y;
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s->rad2 = s->pos.x*s->pos.x + s->pos.y*s->pos.y;
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s->rad = sqrt(s->rad2);
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s->dv.x = 0.0; s->dv.y = 0.0;
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s->b = FALSE;
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}
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static inline void satellite_update_move(satellite_t *s) {
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if (!s->b_old) {
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s->move_old.g.x = -(G*Me/(s->rad2_old*s->rad_old)) * s->pos_old.x;
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s->move_old.g.y = -(G*Me/(s->rad2_old*s->rad_old)) * s->pos_old.y;
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s->move_old.v.x = s->pos.x - s->pos_old.x - 0.5*(s->move_old.g.x + s->dv_old.x);
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s->move_old.v.y = s->pos.y - s->pos_old.y - 0.5*(s->move_old.g.y + s->dv_old.y);
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s->move_old.v_abs = sqrt(s->move_old.v.x*s->move_old.v.x+s->move_old.v.y*s->move_old.v.y);
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s->b_old = TRUE;
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}
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if (!s->b) {
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s->move.g.x = -(G*Me/(s->rad2*s->rad)) * s->pos.x;
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s->move.g.y = -(G*Me/(s->rad2*s->rad)) * s->pos.y;
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s->move.v.x = s->move_old.v.x + s->dv_old.x + 0.5*(s->move_old.g.x + s->move.g.x);
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s->move.v.y = s->move_old.v.y + s->dv_old.y + 0.5*(s->move_old.g.y + s->move.g.y);
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s->move.v_abs = sqrt(s->move.v.x*s->move.v.x+s->move.v.y*s->move.v.y);
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s->b = TRUE;
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}
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}
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#endif
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