lg_quaternions.h

/*
 *      LibGame - Copyright (C) Emmanuel Thomas-Maurin 2011-2025
 *      All rights reserved
 */
 
#ifndef LG_QUATERNIONS_H
#define LG_QUATERNIONS_H
 
#define POW2(x)         (x * x)
#define POW3(x)         (x * x * x)
 
#define RAD_TO_DEG      57.295779513    /* or (180.0 / (float)M_PI) */
#define DEG_TO_RAD      0.017453293     /* or ((float)M_PI / 180.0) */
 
/* Euler angles */
typedef struct {
        double          x_rot;  /* Rotation around X axis in radians - Use DEG_TO_RAD macro when necessary */
        double          y_rot;
        double          z_rot;
} LG_EulerAng;
 
/* Axis and angle */
typedef struct {
        vec3_t          axis;   /* Unit vector - should/must always be normalized ? */
        double          angle;  /* In radians */
} LG_AxAng;
 
/* Quaternion */
typedef struct {
        double          x;      /* Vector part */
        double          y;
        double          z;
        double          w;      /* Scalar part */
} LG_Quat;
 
#define q_id            {0, 0, 0, 1}
 
/* 3 x 3, column-major order matrix -> move that to math_3d.h ? */
typedef union {
        float m[3][3];
        struct {
                float m00, m01, m02;
                float m10, m11, m12;
                float m20, m21, m22;
        };
} mat3_t;
 
#define ROT_SEQ         "XYZ"
/*
 * Convenient precomputed quat values
 *
 * half_pi_up   = -(M_PI / 2.0) * 0.925
 * half_pi_down = -(M_PI / 2.0) * 1.15
 */
typedef struct {
        LG_Quat         id;
        LG_Quat         x_pi;
        LG_Quat         x_half_pi;
        LG_Quat         x_half_pi_inv;
        LG_Quat         x_half_pi_up;
        LG_Quat         x_half_pi_down;
        LG_Quat         y_pi;
        LG_Quat         y_half_pi;
        LG_Quat         y_half_pi_inv;
        LG_Quat         y_half_pi_up;
        LG_Quat         y_half_pi_down;
        LG_Quat         z_pi;
        LG_Quat         z_half_pi;
        LG_Quat         z_half_pi_inv;
        LG_Quat         z_half_pi_up;
        LG_Quat         z_half_pi_down;
        LG_Quat         x_small;
        LG_Quat         x_small_inv;
        LG_Quat         y_small;
        LG_Quat         y_small_inv;
        LG_Quat         z_small;
        LG_Quat         z_small_inv;
}  LG_QuatV;
 
LG_Quat         lg_quat(double, double, double, double);
 
void            lg_quat_normalize(LG_Quat *);
 
LG_Quat         lg_quat_get_normalized(LG_Quat);
 
LG_Quat         lg_quats_multiply(LG_Quat, LG_Quat);
 
LG_Quat         lg_quat_from_euler_ang(LG_EulerAng, const char *);
 
LG_Quat         lg_quat_from_axis_angle(LG_AxAng);
 
void            lg_quat_to_axis_angle(LG_Quat q, LG_AxAng *);
 
LG_Quat         lg_quat_from_3x3_rot_matrix(mat3_t);
 
mat4_t          lg_quat_to_rot_matrix(LG_Quat);
 
vec3_t          lg_quat_rotate_vec3(LG_Quat, vec3_t);
 
int             lg_quat_copy(LG_Quat *, const LG_Quat *);
 
zboolean        lg_quats_are_equal(LG_Quat *, LG_Quat *);
 
void            lg_quat_conjugate(LG_Quat *);
 
LG_Quat         lg_quat_get_conjugate(LG_Quat);
 
void            lg_quat_invert(LG_Quat *);
 
LG_Quat         lg_quat_get_invert(LG_Quat);
 
double          lg_quat_magnitude(LG_Quat);
 
double          lg_quats_dot(LG_Quat *, LG_Quat *);
 
void            lg_quat_set_identity(LG_Quat *);
 
LG_Quat         lg_quat_get_identity();
 
LG_Quat         lg_quat_slerp(LG_Quat *, LG_Quat *, float);
 
LG_EulerAng     lg_euler_ang(double, double, double);
 
LG_AxAng        lg_axis_ang(vec3_t, double);
 
LG_EulerAng     lg_axis_angle_to_euler_ang(LG_AxAng);
 
mat3_t          mat3(float, float, float, float, float, float, float, float, float);
 
mat3_t          m3_transpose(mat3_t);
 
LG_QuatV        *lg_quatv();
 
/* === WARNING: FOLLOWING STUFF IS EXPERIMENTAL - USEFUL ? === */
 
LG_EulerAng     lg_quat_to_euler_ang(LG_Quat);
 
vec3_t          lg_quat_get_yaw_pitch_roll(LG_Quat *);
 
float           lg_quat_get_yaw(LG_Quat *);
 
float           lg_quat_get_pitch(LG_Quat *);
 
float           lg_quat_get_roll(LG_Quat *);
 
#endif /* LG_QUATERNIONS_H */