include/crbn/basic/bbox.hpp

#ifndef __bounding_box_hpp__
#define __bounding_box_hpp__

#include <crbn/basic/vec3.hpp>
#include <crbn/basic/mat4.hpp>

struct bbox
{
  vec3 min, max;

  bbox() : min(1e38f), max(-1e38f) {}
  bbox(const vec3& a, const vec3& b) : min(a), max(b) {}
  bbox(const bbox& b) : min(b.min), max(b.max) {}
};

inline bool inside( bbox& b, vec3& v ) {
  vec3& _min = b.min;
  vec3& _max = b.max;
  return ( (v.x > _min.x) && (v.y > _min.y) && (v.y > _min.y)
           &&
           (v.x < _max.x) && (v.y < _max.y) && (v.y < _max.y) );
}

// a = b U c
inline void merge( bbox& a, bbox& b, bbox& c ) {
  vmin( a.min, b.min, c.min );
  vmax( a.max, b.max, c.max );
}

// a = a U b
inline void merge( bbox& a, bbox& b ) {
  vmin( a.min, a.min, b.min );
  vmax( a.max, a.max, b.max );
}

// a = b * m
inline void transform( bbox& a, bbox& b, mat4& m ) {
    vec3& mi = b.min;
    vec3& ma = b.max;
    vec3 am, aM;
    vec3 vec, va, vb;

    // 1
    vec = vec3( mi.x, mi.y, mi.z );
    mmulp( va, m, vec );

    // 2
    vec = vec3( mi.x, mi.y, ma.z );
    mmulp( vb, m, vec );
    vmin( am, va, vb );
    vmax( aM, va, vb );

    // 3
    vec = vec3( mi.x, ma.y, mi.z );
    mmulp( va, m, vec );
    vmin( am, am, va );
    vmax( aM, aM, va );

    // 4
    vec = vec3( mi.x, ma.y, ma.z );
    mmulp( va, m, vec );
    vmin( am, am, va );
    vmax( aM, aM, va );

    // 5
    vec = vec3( ma.x, mi.y, mi.z );
    mmulp( va, m, vec );
    vmin( am, am, va );
    vmax( aM, aM, va );

    // 6
    vec = vec3( ma.x, mi.y, ma.z );
    mmulp( va, m, vec );
    vmin( am, am, va );
    vmax( aM, aM, va );

    // 7
    vec = vec3( ma.x, ma.y, mi.z );
    mmulp( va, m, vec );
    vmin( am, am, va );
    vmax( aM, aM, va );

    // 8
    vec = vec3( ma.x, mi.y, ma.z );
    mmulp( va, m, vec );
    vmin( a.min, am, va );
    vmax( a.max, aM, va );
}

// Are the two boxes overlapping ?
inline bool overlap(const bbox& a, const bbox& b) {
  return ( (a.min.x <= b.max.x) &&
           (a.min.y <= b.max.y) &&
           (a.min.z <= b.max.z) &&
           (b.min.x <= a.max.x) &&
           (b.min.y <= a.max.y) &&
           (b.min.z <= a.max.z) );
}

#endif // __bounding_box_hpp__

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