1 /* Copyright (c) 2013 Scott Lembcke and Howling Moon Software
2 *
3 * Permission is hereby granted, free of charge, to any person obtaining a copy
4 * of this software and associated documentation files (the "Software"), to deal
5 * in the Software without restriction, including without limitation the rights
6 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
7 * copies of the Software, and to permit persons to whom the Software is
8 * furnished to do so, subject to the following conditions:
9 *
10 * The above copyright notice and this permission notice shall be included in
11 * all copies or substantial portions of the Software.
12 *
13 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
14 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
15 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
16 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
17 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
18 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
19 * SOFTWARE.
20 */
21
22 #ifndef CHIPMUNK_BB_H
23 #define CHIPMUNK_BB_H
24
25 #include "chipmunk_types.h"
26 #include "cpVect.h"
27
28 /// @defgroup cpBBB cpBB
29 /// Chipmunk's axis-aligned 2D bounding box type along with a few handy routines.
30 /// @{
31
32 /// Chipmunk's axis-aligned 2D bounding box type. (left, bottom, right, top)
33 typedef struct cpBB{
34 cpFloat l, b, r ,t;
35 } cpBB;
36
37 /// Convenience constructor for cpBB structs.
cpBBNew(const cpFloat l,const cpFloat b,const cpFloat r,const cpFloat t)38 static inline cpBB cpBBNew(const cpFloat l, const cpFloat b, const cpFloat r, const cpFloat t)
39 {
40 cpBB bb = {l, b, r, t};
41 return bb;
42 }
43
44 /// Constructs a cpBB centered on a point with the given extents (half sizes).
45 static inline cpBB
cpBBNewForExtents(const cpVect c,const cpFloat hw,const cpFloat hh)46 cpBBNewForExtents(const cpVect c, const cpFloat hw, const cpFloat hh)
47 {
48 return cpBBNew(c.x - hw, c.y - hh, c.x + hw, c.y + hh);
49 }
50
51 /// Constructs a cpBB for a circle with the given position and radius.
cpBBNewForCircle(const cpVect p,const cpFloat r)52 static inline cpBB cpBBNewForCircle(const cpVect p, const cpFloat r)
53 {
54 return cpBBNewForExtents(p, r, r);
55 }
56
57 /// Returns true if @c a and @c b intersect.
cpBBIntersects(const cpBB a,const cpBB b)58 static inline cpBool cpBBIntersects(const cpBB a, const cpBB b)
59 {
60 return (a.l <= b.r && b.l <= a.r && a.b <= b.t && b.b <= a.t);
61 }
62
63 /// Returns true if @c other lies completely within @c bb.
cpBBContainsBB(const cpBB bb,const cpBB other)64 static inline cpBool cpBBContainsBB(const cpBB bb, const cpBB other)
65 {
66 return (bb.l <= other.l && bb.r >= other.r && bb.b <= other.b && bb.t >= other.t);
67 }
68
69 /// Returns true if @c bb contains @c v.
cpBBContainsVect(const cpBB bb,const cpVect v)70 static inline cpBool cpBBContainsVect(const cpBB bb, const cpVect v)
71 {
72 return (bb.l <= v.x && bb.r >= v.x && bb.b <= v.y && bb.t >= v.y);
73 }
74
75 /// Returns a bounding box that holds both bounding boxes.
cpBBMerge(const cpBB a,const cpBB b)76 static inline cpBB cpBBMerge(const cpBB a, const cpBB b){
77 return cpBBNew(
78 cpfmin(a.l, b.l),
79 cpfmin(a.b, b.b),
80 cpfmax(a.r, b.r),
81 cpfmax(a.t, b.t)
82 );
83 }
84
85 /// Returns a bounding box that holds both @c bb and @c v.
cpBBExpand(const cpBB bb,const cpVect v)86 static inline cpBB cpBBExpand(const cpBB bb, const cpVect v){
87 return cpBBNew(
88 cpfmin(bb.l, v.x),
89 cpfmin(bb.b, v.y),
90 cpfmax(bb.r, v.x),
91 cpfmax(bb.t, v.y)
92 );
93 }
94
95 /// Returns the center of a bounding box.
96 static inline cpVect
cpBBCenter(cpBB bb)97 cpBBCenter(cpBB bb)
98 {
99 return cpvlerp(cpv(bb.l, bb.b), cpv(bb.r, bb.t), 0.5f);
100 }
101
102 /// Returns the area of the bounding box.
cpBBArea(cpBB bb)103 static inline cpFloat cpBBArea(cpBB bb)
104 {
105 return (bb.r - bb.l)*(bb.t - bb.b);
106 }
107
108 /// Merges @c a and @c b and returns the area of the merged bounding box.
cpBBMergedArea(cpBB a,cpBB b)109 static inline cpFloat cpBBMergedArea(cpBB a, cpBB b)
110 {
111 return (cpfmax(a.r, b.r) - cpfmin(a.l, b.l))*(cpfmax(a.t, b.t) - cpfmin(a.b, b.b));
112 }
113
114 /// Returns the fraction along the segment query the cpBB is hit. Returns INFINITY if it doesn't hit.
cpBBSegmentQuery(cpBB bb,cpVect a,cpVect b)115 static inline cpFloat cpBBSegmentQuery(cpBB bb, cpVect a, cpVect b)
116 {
117 cpFloat idx = 1.0f/(b.x - a.x);
118 #ifdef _MSC_VER
119 #pragma warning(disable: 4056)
120 #endif
121 cpFloat tx1 = (bb.l == a.x ? -INFINITY : (bb.l - a.x)*idx);
122 cpFloat tx2 = (bb.r == a.x ? INFINITY : (bb.r - a.x)*idx);
123 cpFloat txmin = cpfmin(tx1, tx2);
124 cpFloat txmax = cpfmax(tx1, tx2);
125
126 cpFloat idy = 1.0f/(b.y - a.y);
127 cpFloat ty1 = (bb.b == a.y ? -INFINITY : (bb.b - a.y)*idy);
128 cpFloat ty2 = (bb.t == a.y ? INFINITY : (bb.t - a.y)*idy);
129 #ifdef _MSC_VER
130 #pragma warning(default: 4056)
131 #endif
132 cpFloat tymin = cpfmin(ty1, ty2);
133 cpFloat tymax = cpfmax(ty1, ty2);
134
135 if(tymin <= txmax && txmin <= tymax){
136 cpFloat min = cpfmax(txmin, tymin);
137 cpFloat max = cpfmin(txmax, tymax);
138
139 if(0.0 <= max && min <= 1.0) return cpfmax(min, 0.0);
140 }
141
142 return INFINITY;
143 }
144
145 /// Return true if the bounding box intersects the line segment with ends @c a and @c b.
cpBBIntersectsSegment(cpBB bb,cpVect a,cpVect b)146 static inline cpBool cpBBIntersectsSegment(cpBB bb, cpVect a, cpVect b)
147 {
148 return (cpBBSegmentQuery(bb, a, b) != INFINITY);
149 }
150
151 /// Clamp a vector to a bounding box.
152 static inline cpVect
cpBBClampVect(const cpBB bb,const cpVect v)153 cpBBClampVect(const cpBB bb, const cpVect v)
154 {
155 return cpv(cpfclamp(v.x, bb.l, bb.r), cpfclamp(v.y, bb.b, bb.t));
156 }
157
158 /// Wrap a vector to a bounding box.
159 static inline cpVect
cpBBWrapVect(const cpBB bb,const cpVect v)160 cpBBWrapVect(const cpBB bb, const cpVect v)
161 {
162 cpFloat dx = cpfabs(bb.r - bb.l);
163 cpFloat modx = cpfmod(v.x - bb.l, dx);
164 cpFloat x = (modx > 0.0f) ? modx : modx + dx;
165
166 cpFloat dy = cpfabs(bb.t - bb.b);
167 cpFloat mody = cpfmod(v.y - bb.b, dy);
168 cpFloat y = (mody > 0.0f) ? mody : mody + dy;
169
170 return cpv(x + bb.l, y + bb.b);
171 }
172
173 /// Returns a bounding box offseted by @c v.
174 static inline cpBB
cpBBOffset(const cpBB bb,const cpVect v)175 cpBBOffset(const cpBB bb, const cpVect v)
176 {
177 return cpBBNew(
178 bb.l + v.x,
179 bb.b + v.y,
180 bb.r + v.x,
181 bb.t + v.y
182 );
183 }
184
185 ///@}
186
187 #endif
188