Polygon LinePolygonIntersection( Polygon poly, float x1, float y1, float x2, float y2 ) {
	int size = poly->numberOfVertices, i, k;
	float x3, y3, x4, y4, xInt, yInt;
	Polygon intersections = NewPolygon(10);
	for (i=0;i<size;i++) {
		x3 = poly->vertices[i].x;
		y3 = poly->vertices[i].y;
		k = ( i + 1 ) % size;
		x4 = poly->vertices[k].x;
		y4 = poly->vertices[k].y;
		k = LineLineIntersection( x1, y1, x2, y2, x3, y3, x4, y4, &xInt, &yInt );
		switch ( k ) {
			case 2: AddPolygonVertex(intersections,x3,y3);
					AddPolygonVertex(intersections,x4,y4);
					break;
			case 1: AddPolygonVertex(intersections,xInt,yInt);
			case 0: break;
		}
	}
	
	return intersections;
	
}
Esempio n. 2
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bool	PhysicsSystem::InsideConcaveShape(const Vector3* shapePoints, const int numPoints, const Vector3& testPoint){

	int intersectionCount = 0;
	//Counting hom many times we cross the line.
	for( int i = 0; i < numPoints; ++i){
		const int i0 = i;
		const int i1 = (i+1)%numPoints;

		const Vector3& p0 = shapePoints[i0];
		const Vector3& p1 = shapePoints[i1];

		bool intersect = LineLineIntersection(Line_c(p0,p1), Line_c(testPoint, testPoint + Vector3(1000,1000,0)));

		if (intersect){
			intersectionCount++;
		}
	}

	//Even = false;
	if(intersectionCount % 2 == 0){
		return false;
	}
	else {return true;}
}