added showcase20 (not in doc yet)

misc/homog2d.cbp

@@ -195,6 +195,7 @@
 		<Unit filename="showcase/showcase17.cpp" />
 		<Unit filename="showcase/showcase18.cpp" />
 		<Unit filename="showcase/showcase19.cpp" />
+		<Unit filename="showcase/showcase20.cpp" />
 		<Unit filename="showcase/showcase2a.cpp" />
 		<Unit filename="showcase/showcase2b.cpp" />
 		<Unit filename="showcase/showcase3.cpp" />

misc/showcase/showcase20.cpp

@@ -0,0 +1,75 @@
+/**
+\file
+\brief Three circles, one fixed and two whose center rotates. Fixed radius.
+It shows the line formed by intersections points. The three lines intersect at same point (black).
+*/
+#define HOMOG2D_USE_OPENCV
+//#define HOMOG2D_DEBUGMODE
+#include "../../homog2d.hpp"
+
+using namespace h2d;
+using namespace h2d::img;
+
+int main( int, const char** )
+{
+	auto nbim = 30; // nb images
+
+	CPolyline pol( 50, 3 );
+	pol.translate( 140, 160 );
+	auto pts = pol.getPts();
+	auto pt0 = pts[0];
+	auto pt1 = pts[1];
+	auto pt2 = pts[2];
+
+	auto k1=5;
+	auto k2=12;
+
+	auto rad0 = 60;
+	auto rad1=70, rad2=80;
+	uint8_t m = 220;
+	for( int i=0; i<nbim; i++ )
+	{
+		auto angle = i * 2. * M_PI / nbim;
+		auto xr1 = std::cos(angle)*k1;
+		auto yr1 = std::sin(angle)*k1;
+		auto xr2 = std::cos(angle)*k2;
+		auto yr2 = std::sin(angle)*k2;
+
+		Point2d p2( pt2 );
+		Point2d p1( pt1 );
+		p1.translate( xr1, -yr1 );
+		p2.translate( xr2, yr2 );
+		Circle cir1( p1, rad1 );
+		Circle cir2( p2, rad2 );
+		Circle cir0( pt0, rad0 );
+
+		Image<cv::Mat> im( 300, 300 );
+		cir0.draw( im, DrawParams().setColor(0,250,0) );
+		cir1.draw( im, DrawParams().setColor(250,0,0) );
+		cir2.draw( im, DrawParams().setColor(0,0,250) );
+#if 0
+		p1.draw( im, DrawParams().setColor(250,0,0) );
+		p2.draw( im, DrawParams().setColor(0,0,250) );
+		pt0.draw( im, DrawParams().setColor(0,250,0) );
+#endif
+		auto int01 = cir0.intersects(cir1).get();
+		auto int02 = cir0.intersects(cir2).get();
+		auto int12 = cir2.intersects(cir1).get();
+
+		auto gray = DrawParams().setColor(200,200,200);
+		auto li01 = int01[0] * int01[1];
+		auto li02 = int02[0] * int02[1];
+		auto li12 = int12[0] * int12[1];
+		li01.draw( im, DrawParams().setColor(m,m,0) );
+		li02.draw( im, DrawParams().setColor(0,m,m) );
+		li12.draw( im, DrawParams().setColor(m,0,m) );
+
+		auto centerpt = li01 * li02;
+		centerpt.draw( im, DrawParams().setColor(0,0,0).setPointStyle(PtStyle::Dot) );
+
+		std::ostringstream oss;
+		oss << "showcase20_" << std::setfill('0') << std::setw(2) <<i << ".png";
+		im.write( oss.str() );
+	}
+}
+