////////////////////////////////////////////////////////////
//~ Tweakable defines

/* How close can non-overlapping shapes be before collision is considered */
#define CLD_CollisionTolerance      0.005f

/* NOTE: Should always be less than tolerance, since colliding = 1 if origin is within this distance. */
#define CLD_MinUniquePtDistSq       (0.001f * 0.001f)

/* To prevent extremely large prototypes when origin is in exact center of rounded feature */
#define CLD_MaxEpaIterations        64

////////////////////////////////////////////////////////////
//~ Shape types

Struct(CLD_Shape)
{
    Vec2 points[8];
    u32 count;
    f32 radius;
};

////////////////////////////////////////////////////////////
//~ Menkowski types

Struct(CLD_SupportPoint)
{
    Vec2 p;
    u32 i;  /* Index of original point in shape */
};

Struct(CLD_MenkowskiPoint)
{
    Vec2 p;                 /* Menkowski difference point */
    CLD_SupportPoint s0;    /* Support point of first shape in dir */
    CLD_SupportPoint s1;    /* Support point of second shape in -dir */
};

Struct(CLD_MenkowskiSimplex)
{
    u32 len;
    CLD_MenkowskiPoint a, b, c;
};

Struct(CLD_MenkowskiFeature)
{
    u32 len;
    CLD_MenkowskiPoint a, b;
};

////////////////////////////////////////////////////////////
//~ Collision types

Struct(CLD_CollisionPoint)
{
    Vec2 point;
    f32 separation;
    u32 id;  /* Based on polygon edge-to-edge */
};

Struct(CLD_Prototype)
{
    Vec2 points[64];
    u32 len;
};

Struct(CLD_CollisionData)
{
    Vec2 normal;
    CLD_CollisionPoint points[2];
    u32 num_points;

    /* For debugging */
    b32 solved;
    CLD_MenkowskiSimplex simplex;
    CLD_Prototype prototype;

    /* For debugging */
    Vec2 a0, b0, a1, b1;
    Vec2 a0_clipped, b0_clipped, a1_clipped, b1_clipped;
};

Struct(CLD_ClosestPointData)
{
    Vec2 p0, p1;
    b32 colliding;

    /* For debugging */
    b32 solved;
    CLD_MenkowskiSimplex simplex;
    CLD_Prototype prototype;
};

////////////////////////////////////////////////////////////
//~ Clipping types

Struct(CLD_ClippedLine)
{
    Vec2 a0_clipped, b0_clipped;
    Vec2 a1_clipped, b1_clipped;
};

////////////////////////////////////////////////////////////
//~ Gjk types

Struct(CLD_GjkData)
{
    CLD_MenkowskiSimplex simplex;
    Vec2 final_dir;

    /* If 1, simplex represents triangle inside of CLD_Menkowski difference
     * encapsulating the origin. If 0, simplex represents the closest
     * feature on CLD_Menkowski difference to the origin. */
    b32 overlapping;

#if COLLIDER_DEBUG
    u32 dbg_step;
#endif
};

////////////////////////////////////////////////////////////
//~ Epa types

Struct(CLD_EpaData)
{
    Vec2 normal;
    CLD_MenkowskiFeature closest_feature;  /* Represents closest feature (edge or point) to origin on CLD_Menkowski difference */

#if COLLIDER_DEBUG
    CLD_Prototype prototype;
    u32 dbg_step;
#endif
};

////////////////////////////////////////////////////////////
//~ Debug helpers

#if COLLIDER_DEBUG
void CLD_DebugBreakable(void);

#define CLD_DBGSTEP \
    dbg_step++; \
    if (dbg_step >= GetGstat(GSTAT_DEBUG_STEPS)) \
    { \
        goto abort; \
    } \
    else if (dbg_step >= GetGstat(GSTAT_DEBUG_STEPS) - 1) \
    { \
        CLD_DebugBreakable(); \
    } (void)0
#else
#define CLD_DBGSTEP
#endif

////////////////////////////////////////////////////////////
//~ Shape operations

CLD_Shape CLD_ShapeFromQuad(Quad quad);

////////////////////////////////////////////////////////////
//~ Menkowski operations

CLD_SupportPoint CLD_SupportPointFromDirEx(CLD_Shape *shape, Xform xf, Vec2 dir, i32 ignore);
CLD_SupportPoint CLD_SupportPointFromDir(CLD_Shape *shape, Xform xf, Vec2 dir);
CLD_MenkowskiPoint CLD_MenkowskiPointFromDir(CLD_Shape *shape0, CLD_Shape *shape1, Xform xf0, Xform xf1, Vec2 dir);

////////////////////////////////////////////////////////////
//~ Aabb operations

Aabb CLD_AabbFromShape(CLD_Shape *shape, Xform xf);
Aabb CLD_CombineAabb(Aabb b0, Aabb b1);
b32 CLD_TestAabb(Aabb box0, Aabb box1);

////////////////////////////////////////////////////////////
//~ Gjk operations

#if COLLIDER_DEBUG
CLD_GjkData CLD_GjkDataFromShapes(CLD_Shape *shape0, CLD_Shape *shape1, Xform xf0, Xform xf1, f32 min_unique_pt_dist_sq, u32 dbg_step);
#else
CLD_GjkData CLD_GjkDataFromShapes(CLD_Shape *shape0, CLD_Shape *shape1, Xform xf0, Xform xf1, f32 min_unique_pt_dist_sq);
#endif

////////////////////////////////////////////////////////////
//~ Epa operations

#if COLLIDER_DEBUG
CLD_EpaData CLD_EpaDataFromShapes(CLD_Shape *shape0, CLD_Shape *shape1, Xform xf0, Xform xf1, CLD_GjkData gjk_result, f32 min_unique_pt_dist_sq, u32 max_iterations, u32 dbg_step);
#else
CLD_EpaData CLD_EpaDataFromShapes(CLD_Shape *shape0, CLD_Shape *shape1, Xform xf0, Xform xf1, CLD_GjkData gjk_result, f32 min_unique_pt_dist_sq, u32 max_iterations);
#endif

////////////////////////////////////////////////////////////
//~ Clipping operations

CLD_ClippedLine CLD_ClipLineToLine(Vec2 a0, Vec2 b0, Vec2 a1, Vec2 b1, Vec2 normal);
Vec2 CLD_ClipPointToLine(Vec2 a, Vec2 b, Vec2 p, Vec2 normal);

////////////////////////////////////////////////////////////
//~ Collision point operations

CLD_CollisionData CLD_CollisionDataFromShapes(CLD_Shape *shape0, CLD_Shape *shape1, Xform xf0, Xform xf1);

////////////////////////////////////////////////////////////
//~ Closest point operations

CLD_ClosestPointData CLD_ClosestPointDataFromShapes(CLD_Shape *shape0, CLD_Shape *shape1, Xform xf0, Xform xf1);

////////////////////////////////////////////////////////////
//~ Time of impact operations

f32 CLD_TimeOfImpact(CLD_Shape *c0, CLD_Shape *c1, Xform xf0_t0, Xform xf1_t0, Xform xf0_t1, Xform xf1_t1, f32 tolerance, u32 max_iterations);

////////////////////////////////////////////////////////////
//~ Point cloud debugging operations

Vec2Array CLD_Menkowski(Arena *arena, CLD_Shape *shape0, CLD_Shape *shape1, Xform xf0, Xform xf1, u32 detail);
Vec2Array CLD_PointCloud(Arena *arena, CLD_Shape *shape0, CLD_Shape *shape1, Xform xf0, Xform xf1);