// Draw a diagram of the scattering angles in the g p -> pi+pi- reaction
// similar to the one from Stefan Strauch's document


void scattering_angles(void)
{
	TCanvas *c1 = new TCanvas("c1", "", 1000, 500);
	c1->Range(-1.0, -1.0, +1.0, +1.0);
	
	gStyle->SetLineWidth(3);
	
	
	// Proton scattering plane
	double pplane_x[] = {-1.0, -0.5, 1.0, 0.5, -1.0};
	double pplane_y[] = {-1.0, 0.45, 0.45, -1.0, -1.0};
	TPolyLine *pplane = new TPolyLine(5, pplane_x, pplane_y);
	pplane->SetFillColor(kGray);
	pplane->SetFillStyle(3002);

	// Pion scattering plane upper
	double piplane_x[] = {0.0, -0.10, 0.25, 0.35, 0.0};
	double piplane_y[] = {-0.275, 0.325, 1.0, 0.40, -0.275};
	TPolyLine *piplane_up = new TPolyLine(4, piplane_x, piplane_y);
	piplane_up->SetFillColor(kYellow);
	piplane_up->SetFillStyle(3002);

	// Pion scattering plane lower
	for(int i=0; i<5; i++){
		piplane_x[i] += 0.1;
		piplane_y[i] -= 0.6;
	}
	TPolyLine *piplane_dn = new TPolyLine(5, piplane_x, piplane_y);
	piplane_dn->SetFillColor(kYellow);
	piplane_dn->SetFillStyle(3001);
	piplane_dn->SetLineStyle(2);
	
	// Incident photon
	TCurlyLine *gamma1 = new TCurlyLine(-0.6, -0.275, -0.02, -0.275);
	gamma1->SetWavy();
	gamma1->SetWaveLength(0.06);
	gamma1->SetAmplitude(0.02);
	gamma1->Draw();
	TArrow *gamma1_arrow = new TArrow(-0.05, -0.275, -0.02, -0.275, 0.03, "->");

	// Incident photon polarization (at photon)
	TArrow *gamma1_polarization = new TArrow(-0.6, -0.275, -0.6, 0.1, 0.02, "-|>");
	gamma1_polarization->SetLineColor(kGray+2);
	gamma1_polarization->SetFillColor(kGray+2);
	gamma1_polarization->SetLineStyle(2);
	
	// Incident photon polarization (at pipi scattering plane)
	TArrow *gamma1_polarization_pipi = new TArrow(0.35, 0.40, 0.35, 0.82, 0.02, "-|>");
	gamma1_polarization_pipi->SetLineColor(kGray+2);
	gamma1_polarization_pipi->SetFillColor(kGray+2);
	gamma1_polarization_pipi->SetLineStyle(2);
	
	// Drop shadow for "Z" direction to show phi_pipi angle 
	TArrow *Z_drop_shadow_arrow = new TArrow(-0.6, -0.275, -0.5, 0.0875, 0.02, "-|>");
	Z_drop_shadow_arrow->SetFillColor(kGray+2);
	Z_drop_shadow_arrow->SetLineColor(kGray+2);
	Z_drop_shadow_arrow->SetLineStyle(9);
	
	// pi+
	TArrow *pip_arrow = new TArrow(0.0, -0.275, 0.20, 0.75, 0.03, "->");
	pip_arrow->SetLineColor(kRed);

	// pi-
	TArrow *pim_arrow = new TArrow(0.0, -0.275, 0.40, -0.200, 0.03, "->");
	pim_arrow->SetLineColor(kBlue);
	
	// Incident proton
	TArrow *iproton_arrow = new TArrow(0.6, -0.275, 0.01, -0.275, 0.03, "->");
	iproton_arrow->SetLineWidth(5);
	iproton_arrow->SetLineColor(kRed+2);
	
	// Final state proton
	TArrow *fproton_arrow = new TArrow(0.0, -0.275, -0.275, -0.80, 0.03, "->");
	fproton_arrow->SetLineWidth(5);
	fproton_arrow->SetLineColor(kRed+2);
	
	// "Z" direction (pi+pi- total momentum)
	TArrow *Z_arrow = new TArrow(0.0, -0.275, 0.290, 0.280, 0.02, "-|>");
	Z_arrow->SetLineWidth(4);

	// "X" direction (in proton scattering plane, perpendicular to FS proton)
	TArrow *X_arrow = new TArrow(0.0, -0.275, -0.277, 0.085, 0.02, "-|>");
	X_arrow->SetLineStyle(9);
	X_arrow->SetLineWidth(4);
	
	// theta arc
	TEllipse *theta_arc = new TEllipse(0.0, -0.275, 0.2, 0.5, 38.0, 63.0);
	theta_arc->SetNoEdges();
	theta_arc->SetLineWidth(2);
	theta_arc->SetFillStyle(0);

	// theta_cm arc
	TEllipse *theta_cm_arc = new TEllipse(0.0, -0.275, 0.30, 0.70, 0.0, 38.0);
	theta_cm_arc->SetNoEdges();
	theta_cm_arc->SetLineWidth(2);
	theta_cm_arc->SetFillStyle(0);
	
	// phi_cm arc
	TEllipse *phi_arc = new TEllipse(0.0, -0.275, 0.20, 0.55, 114.0, 155.0);
	phi_arc->SetNoEdges();
	phi_arc->SetLineWidth(2);
	phi_arc->SetFillStyle(0);
	
	// phi_pipi arc
	TEllipse *phi_pipi_arc = new TEllipse(-0.6, -0.275, 0.035, 0.2, 35.0, 90.0);
	phi_pipi_arc->SetNoEdges();
	phi_pipi_arc->SetLineWidth(2);
	phi_pipi_arc->SetFillStyle(0);

	// psi_pipi arc
	TEllipse *psi_pipi_arc = new TEllipse(0.35, 0.40, 0.15, 0.2, 90.0, 103.0);
	psi_pipi_arc->SetNoEdges();
	psi_pipi_arc->SetLineWidth(2);
	psi_pipi_arc->SetFillStyle(0);

	// Latex labels
	TLatex t;
	t.SetTextSize(0.11);
	t.SetTextAlign(22);

	// Draw all items in appropriate order
	piplane_dn->Draw();
	piplane_dn->Draw("f");

	pim_arrow->Draw();
	t.SetTextColor(kBlue);
	t.DrawLatex(0.367, -0.089, "#pi^{-}");

	pplane->Draw();
	pplane->Draw("f");
	piplane_up->Draw();
	piplane_up->Draw("f");

	gamma1_arrow->Draw();
	gamma1_polarization->Draw();
	gamma1_polarization_pipi->Draw();
	Z_drop_shadow_arrow->Draw();
	pip_arrow->Draw();
	iproton_arrow->Draw();
	fproton_arrow->Draw();
	Z_arrow->Draw();
	X_arrow->Draw();
	theta_arc->Draw();
	theta_cm_arc->Draw();
	phi_arc->Draw();
	phi_pipi_arc->Draw();
	psi_pipi_arc->Draw();
	
	t.SetTextColor(kBlack);
	t.DrawLatex(-0.65, -0.275, "#vec{#gamma}");
	t.SetTextColor(kRed+2);
	t.DrawLatex(0.65, -0.275, "#it{Z}");
	t.DrawLatex(-0.35, -0.85, "#it{Z'}");
	t.SetTextColor(kRed);
	t.DrawLatex(0.221, 0.826, "#pi^{+}");
	
	t.SetTextSize(0.07);
	t.SetTextColor(kBlack);
	t.DrawLatex(0.237, -0.097, "#it{#theta_{cm}}");
	t.DrawLatex(0.110, 0.055, "#it{#theta}");
	t.DrawLatex(-0.124, 0.064, "#it{#phi}");
	t.DrawLatex(0.297, 0.369, "#it{Z}");
	t.DrawLatex(-0.305, 0.144, "#it{X}");
	
	
	t.SetTextSize(0.07);
	t.DrawLatex(0.378, 0.673, "#it{#psi}");
	t.SetTextSize(0.03);
	t.DrawLatex(0.398, 0.636, "#it{#pi#pi}");
	
	t.SetTextSize(0.07);
	t.DrawLatex(-0.578, 0.008, "#it{#phi}");
	t.SetTextSize(0.03);
	t.DrawLatex(-0.556, -0.042, "#it{#pi#pi}");

	t.SetTextColor(kGray+2);
	t.SetTextSize(0.06);
	t.DrawLatex(-0.572, 0.165, "#vec{#voidn}");
	t.DrawLatex(0.351, 0.907, "#vec{#voidn}");

	c1->SaveAs("scattering_angles.png");
	c1->SaveAs("scattering_angles.pdf");
}

void AddMiddleArrowHead(TCurlyLine *cl)
{
	double xmid = (cl->GetStartX() + cl->GetEndX())/2.0;
	double ymid = (cl->GetStartY() + cl->GetEndY())/2.0;
	double dX = (cl->GetEndX() - cl->GetStartX())/1000.0;
	double dY = (cl->GetEndY() - cl->GetStartY())/1000.0;
	
	xmid += 10.0*dX;
	ymid += 10.0*dY;

	TArrow *arrow = new TArrow(xmid, ymid, xmid+dX, ymid+dY, 0.05, "->-");
	arrow->Draw();
	
	
	
}