188 lines
5.3 KiB
C
188 lines
5.3 KiB
C
/* Copyright (c) 2013 Scott Lembcke and Howling Moon Software
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*/
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#ifndef CHIPMUNK_BB_H
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#define CHIPMUNK_BB_H
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#include "chipmunk_types.h"
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#include "cpVect.h"
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/// @defgroup cpBBB cpBB
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/// Chipmunk's axis-aligned 2D bounding box type along with a few handy routines.
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/// @{
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/// Chipmunk's axis-aligned 2D bounding box type. (left, bottom, right, top)
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typedef struct cpBB{
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cpFloat l, b, r ,t;
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} cpBB;
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/// Convenience constructor for cpBB structs.
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static inline cpBB cpBBNew(const cpFloat l, const cpFloat b, const cpFloat r, const cpFloat t)
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{
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cpBB bb = {l, b, r, t};
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return bb;
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}
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/// Constructs a cpBB centered on a point with the given extents (half sizes).
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static inline cpBB
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cpBBNewForExtents(const cpVect c, const cpFloat hw, const cpFloat hh)
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{
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return cpBBNew(c.x - hw, c.y - hh, c.x + hw, c.y + hh);
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}
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/// Constructs a cpBB for a circle with the given position and radius.
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static inline cpBB cpBBNewForCircle(const cpVect p, const cpFloat r)
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{
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return cpBBNewForExtents(p, r, r);
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}
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/// Returns true if @c a and @c b intersect.
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static inline cpBool cpBBIntersects(const cpBB a, const cpBB b)
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{
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return (a.l <= b.r && b.l <= a.r && a.b <= b.t && b.b <= a.t);
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}
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/// Returns true if @c other lies completely within @c bb.
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static inline cpBool cpBBContainsBB(const cpBB bb, const cpBB other)
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{
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return (bb.l <= other.l && bb.r >= other.r && bb.b <= other.b && bb.t >= other.t);
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}
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/// Returns true if @c bb contains @c v.
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static inline cpBool cpBBContainsVect(const cpBB bb, const cpVect v)
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{
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return (bb.l <= v.x && bb.r >= v.x && bb.b <= v.y && bb.t >= v.y);
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}
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/// Returns a bounding box that holds both bounding boxes.
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static inline cpBB cpBBMerge(const cpBB a, const cpBB b){
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return cpBBNew(
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cpfmin(a.l, b.l),
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cpfmin(a.b, b.b),
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cpfmax(a.r, b.r),
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cpfmax(a.t, b.t)
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);
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}
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/// Returns a bounding box that holds both @c bb and @c v.
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static inline cpBB cpBBExpand(const cpBB bb, const cpVect v){
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return cpBBNew(
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cpfmin(bb.l, v.x),
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cpfmin(bb.b, v.y),
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cpfmax(bb.r, v.x),
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cpfmax(bb.t, v.y)
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);
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}
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/// Returns the center of a bounding box.
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static inline cpVect
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cpBBCenter(cpBB bb)
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{
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return cpvlerp(cpv(bb.l, bb.b), cpv(bb.r, bb.t), 0.5f);
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}
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/// Returns the area of the bounding box.
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static inline cpFloat cpBBArea(cpBB bb)
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{
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return (bb.r - bb.l)*(bb.t - bb.b);
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}
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/// Merges @c a and @c b and returns the area of the merged bounding box.
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static inline cpFloat cpBBMergedArea(cpBB a, cpBB b)
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{
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return (cpfmax(a.r, b.r) - cpfmin(a.l, b.l))*(cpfmax(a.t, b.t) - cpfmin(a.b, b.b));
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}
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/// Returns the fraction along the segment query the cpBB is hit. Returns INFINITY if it doesn't hit.
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static inline cpFloat cpBBSegmentQuery(cpBB bb, cpVect a, cpVect b)
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{
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cpVect delta = cpvsub(b, a);
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cpFloat tmin = -INFINITY, tmax = INFINITY;
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if(delta.x == 0.0f){
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if(a.x < bb.l || bb.r < a.x) return INFINITY;
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} else {
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cpFloat t1 = (bb.l - a.x)/delta.x;
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cpFloat t2 = (bb.r - a.x)/delta.x;
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tmin = cpfmax(tmin, cpfmin(t1, t2));
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tmax = cpfmin(tmax, cpfmax(t1, t2));
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}
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if(delta.y == 0.0f){
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if(a.y < bb.b || bb.t < a.y) return INFINITY;
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} else {
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cpFloat t1 = (bb.b - a.y)/delta.y;
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cpFloat t2 = (bb.t - a.y)/delta.y;
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tmin = cpfmax(tmin, cpfmin(t1, t2));
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tmax = cpfmin(tmax, cpfmax(t1, t2));
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}
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if(tmin <= tmax && 0.0f <= tmax && tmin <= 1.0f){
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return cpfmax(tmin, 0.0f);
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} else {
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return INFINITY;
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}
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}
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/// Return true if the bounding box intersects the line segment with ends @c a and @c b.
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static inline cpBool cpBBIntersectsSegment(cpBB bb, cpVect a, cpVect b)
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{
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return (cpBBSegmentQuery(bb, a, b) != INFINITY);
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}
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/// Clamp a vector to a bounding box.
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static inline cpVect
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cpBBClampVect(const cpBB bb, const cpVect v)
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{
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return cpv(cpfclamp(v.x, bb.l, bb.r), cpfclamp(v.y, bb.b, bb.t));
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}
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/// Wrap a vector to a bounding box.
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static inline cpVect
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cpBBWrapVect(const cpBB bb, const cpVect v)
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{
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cpFloat dx = cpfabs(bb.r - bb.l);
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cpFloat modx = cpfmod(v.x - bb.l, dx);
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cpFloat x = (modx > 0.0f) ? modx : modx + dx;
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cpFloat dy = cpfabs(bb.t - bb.b);
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cpFloat mody = cpfmod(v.y - bb.b, dy);
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cpFloat y = (mody > 0.0f) ? mody : mody + dy;
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return cpv(x + bb.l, y + bb.b);
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}
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/// Returns a bounding box offseted by @c v.
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static inline cpBB
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cpBBOffset(const cpBB bb, const cpVect v)
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{
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return cpBBNew(
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bb.l + v.x,
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bb.b + v.y,
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bb.r + v.x,
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bb.t + v.y
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);
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}
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///@}
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#endif
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