cpBB.h

/* Copyright (c) 2007 Scott Lembcke
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */


typedef struct cpBB{
  cpFloat l, b, r ,t;
} cpBB;

static inline cpBB cpBBNew(const cpFloat l, const cpFloat b, const cpFloat r, const cpFloat t)
{
  cpBB bb = {l, b, r, t};
  return bb;
}

static inline cpBB cpBBNewForCircle(const cpVect p, const cpFloat r)
{
  return cpBBNew(p.x - r, p.y - r, p.x + r, p.y + r);
}

static inline cpBool cpBBIntersects(const cpBB a, const cpBB b)
{
  return (a.l <= b.r && b.l <= a.r && a.b <= b.t && b.b <= a.t);
}

static inline cpBool cpBBContainsBB(const cpBB bb, const cpBB other)
{
  return (bb.l <= other.l && bb.r >= other.r && bb.b <= other.b && bb.t >= other.t);
}

static inline cpBool cpBBContainsVect(const cpBB bb, const cpVect v)
{
  return (bb.l <= v.x && bb.r >= v.x && bb.b <= v.y && bb.t >= v.y);
}

static inline cpBB cpBBMerge(const cpBB a, const cpBB b){
  return cpBBNew(
    cpfmin(a.l, b.l),
    cpfmin(a.b, b.b),
    cpfmax(a.r, b.r),
    cpfmax(a.t, b.t)
  );
}

static inline cpBB cpBBExpand(const cpBB bb, const cpVect v){
  return cpBBNew(
    cpfmin(bb.l, v.x),
    cpfmin(bb.b, v.y),
    cpfmax(bb.r, v.x),
    cpfmax(bb.t, v.y)
  );
}

static inline cpFloat cpBBArea(cpBB bb)
{
  return (bb.r - bb.l)*(bb.t - bb.b);
}

static inline cpFloat cpBBMergedArea(cpBB a, cpBB b)
{
  return (cpfmax(a.r, b.r) - cpfmin(a.l, b.l))*(cpfmax(a.t, b.t) - cpfmin(a.b, b.b));
}

static inline cpFloat cpBBSegmentQuery(cpBB bb, cpVect a, cpVect b)
{
  cpFloat idx = 1.0f/(b.x - a.x);
  cpFloat tx1 = (bb.l == a.x ? -INFINITY : (bb.l - a.x)*idx);
  cpFloat tx2 = (bb.r == a.x ?  INFINITY : (bb.r - a.x)*idx);
  cpFloat txmin = cpfmin(tx1, tx2);
  cpFloat txmax = cpfmax(tx1, tx2);
  
  cpFloat idy = 1.0f/(b.y - a.y);
  cpFloat ty1 = (bb.b == a.y ? -INFINITY : (bb.b - a.y)*idy);
  cpFloat ty2 = (bb.t == a.y ?  INFINITY : (bb.t - a.y)*idy);
  cpFloat tymin = cpfmin(ty1, ty2);
  cpFloat tymax = cpfmax(ty1, ty2);
  
  if(tymin <= txmax && txmin <= tymax){
    cpFloat min = cpfmax(txmin, tymin);
    cpFloat max = cpfmin(txmax, tymax);
    
    if(0.0 <= max && min <= 1.0) return cpfmax(min, 0.0);
  }
  
  return INFINITY;
}

static inline cpBool cpBBIntersectsSegment(cpBB bb, cpVect a, cpVect b)
{
  return (cpBBSegmentQuery(bb, a, b) != INFINITY);
}

cpVect cpBBClampVect(const cpBB bb, const cpVect v); // clamps the vector to lie within the bbox

// TODO edge case issue
cpVect cpBBWrapVect(const cpBB bb, const cpVect v); // wrap a vector to a bbox