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#ifndef PHYSICS_H
#define PHYSICS_H
#include "common.h"
typedef enum {
PHYS_SHAPE_BOX,
PHYS_SHAPE_SPHERE,
PHYS_SHAPE_CAPSULE,
PHYS_SHAPE_CYLINDER,
PHYS_SHAPE_CONVEX_HULL,
PHYS_SHAPE_STATIC_TRIMESH,
} PhysicsShapeTag;
typedef enum {
PHYS_JOINT_SPHERICAL,
PHYS_JOINT_REVOLUTE,
PHYS_JOINT_PRISMATIC,
PHYS_JOINT_WELD,
PHYS_JOINT_WHEEL,
PHYS_JOINT_DISTANCE,
} PhysicsJointTag;
typedef enum {
PHYS_JOINT_LIMIT,
PHYS_JOINT_SPRING,
PHYS_JOINT_MOTOR,
} PhysicsJointFlags;
typedef enum {
PHYS_MODE_STATIC,
PHYS_MODE_KINEMATIC,
PHYS_MODE_DYNAMIC,
} PhysicsMode;
typedef enum {
PHYS_MASK_DEFAULT,
PHYS_MASK_WORLD,
PHYS_MASK_PROP,
PHYS_MASK_PLAYER,
PHYS_MASK_PARTICLE,
PHYS_MASK_EDITOR_SELECTABLE,
PHYS_MASK_EDITOR_RAYCAST,
} PhysicsMask;
typedef struct {
PhysicsShapeTag tag;
union {
struct {
Vec3 sz;
} Box;
struct {
f32 radius;
} Sphere;
struct {
f32 height, radius;
} Capsule, Cylinder;
struct {
Vec3 *points;
u32 point_cnt;
} ConvexHull;
struct {
Vec3 *points;
u32 *indices;
u32 point_cnt, idx_cnt;
} TriMesh;
};
/* local to body */
Vec3 pos;
Quaternion rot;
f32 density, friction, restitution;
Flags32 category_bits, mask_bits;
} PhysicsShape;
typedef struct {
PhysicsShape *shapes;
u32 shape_cnt;
/* local to entity */
Vec3 pos;
Quaternion rot;
f32 linear_damping, angular_damping;
f32 gravity_scale;
PhysicsMode mode;
bool enable_sleep;
} PhysicsBody;
/*
physics joint fields meaning changes depending on their context.
anchor_a/frame_rot_a define the joint frame local to body_a.
anchor_b/frame_rot_b define the joint frame local to body_b.
frame rotations are normalized quaternions.
lower/upper are generic limits
- revolute: radians
- prismatic: metres
- distance: metres
- wheel: suspension travel
springs:
- spring_hz: frequency of the spring response; higher = stiffer/faster
- spring_damping: damping ratio; controls oscillation
motors:
revolute:
motor_speed = angular velocity
motor_force = maximum torque
prismatic:
motor_speed = linear velocity
motor_force = maximum force
wheel:
motor_speed = wheel angular velocity
motor_force = maximum drive/braking torque
*/
typedef struct {
PhysicsJointTag tag;
u32 body_a, body_b;
Flags32 flags;
Vec3 anchor_a, anchor_b;
Quaternion frame_rot_a, frame_rot_b;
// Vec3 axis_a, axis_b;
f32 lower, upper;
f32 spring_hz, spring_damping;
f32 motor_speed, motor_force;
} PhysicsJoint;
typedef struct {
u64 entity_id;
b3BodyId id;
b3ShapeId *shapes; // count is stored in PhysicsCmp
b3MeshData **meshes; // same count, null for non mesh types
} PhysicsBodyRuntime;
typedef struct {
b3WorldDef world_def;
b3WorldId world_id;
bool simulate;
} PhysicsInfo;
extern PhysicsInfo physics;
void physics_init(void);
void physics_exit(void);
void physics_update(void);
#endif
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