#include <stdio.h> #include <stdlib.h> struct pt { float x,y; }; struct quat { pt points[4]; }; float crossmulti2d( float x1, float y1, float x2, float y2) { return x1 * y2 - x2 * y1; } bool inquat( quat _q, pt _pt) { pt vec1, vec2; vec1.x = _q.points[1].x - _q.points[0].x; vec1.y = _q.points[1].y - _q.points[0].y; vec2.x = _pt.x - _q.points[0].x; vec2.y = _pt.y - _q.points[0].y; if( crossmulti2d( vec2.x, vec2.y, vec1.x, vec1.y ) < 0 ) { return false; } vec1.x = _q.points[2].x - _q.points[1].x; vec1.y = _q.points[2].y - _q.points[1].y; vec2.x = _pt.x - _q.points[1].x; vec2.y = _pt.y - _q.points[1].y; if( crossmulti2d(vec2.x, vec2.y, vec1.x, vec1.y) < 0 ) { return false; } vec1.x = _q.points[3].x - _q.points[2].x; vec1.y = _q.points[3].y - _q.points[2].y; vec2.x = _pt.x - _q.points[2].x; vec2.y = _pt.y - _q.points[2].y; if( crossmulti2d(vec2.x, vec2.y, vec1.x, vec1.y) < 0 ) { return false; } vec1.x = _q.points[0].x - _q.points[3].x; vec1.y = _q.points[0].y - _q.points[3].y; vec2.x = _pt.x - _q.points[3].x; vec2.y = _pt.y - _q.points[3].y; if( crossmulti2d(vec2.x, vec2.y, vec1.x, vec1.y ) < 0 ) { return false; } return true; } int main() { quat shape = { { {1, 1},{2, 1}, {1, 0},{0, 0} } }; pt tests[] = { {0.0, 1.0}, {1.0, 0.5}, {1.5, 0}, {1.5, 0.5}, {1.5, 0.52}, {1.5, 0.49} }; for(int i =0; i<sizeof(tests)/sizeof(pt); ++i) { if( inquat(shape, tests[i]) == true ) { printf("pass\n"); } else { printf("failed\n"); } } return 0; }
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