Function plot_vector

plugin/seq/plotPDF.cpp:3379–3427

    return;
} //


//----------------------------------------------------------------------
// vector field
//----------------------------------------------------------------------

void plot_vector( std::stringstream &Content,
		  const double arrow_origin_x, const double arrow_origin_y,
		  const double vector_x, const double vector_y, const double vector_norm2,
		  const double alength_scale, const double ahead_scale,
		  const double x0, const double y0, const double scale, const double ar,
		  const double fmin, const double fmax,
		  const bool unit_arrow, const bool logscale,
		  const KNM<double> &palette, const bool monochrome )
{
    std::stringstream &st = Content;
    const double &r       = scale;

    const double &ox = arrow_origin_x;
    const double &oy = arrow_origin_y;

    const double AH_SIZE = (alength_scale > 0)? (PLOTPDFVAR::DEFAULT_ARROW_HEAD_SIZE * ahead_scale): (PLOTPDFVAR::DEFAULT_ARROW_HEAD_SIZE * (-ahead_scale));
    const double &AH_ANGLE = PLOTPDFVAR::ARROW_HEAD_ANGLE;

    // what happen if (fmin == 0) && logscale ?
    const double favg = logscale? (sqrt(fmax*fmin)): (fmax+fmin)/2;

    // scaled arrow length is arrow_scale * cf2, which is truncated if greater than fmax
    const double &as = alength_scale;
    const double alength = (unit_arrow)? (as*favg)/fmax*PLOTPDFVAR::MAX_ARROW_LENGTH:
	( (logscale)? as*(log(vector_norm2/fmin))/(log(fmax/fmin))*PLOTPDFVAR::MAX_ARROW_LENGTH: as*vector_norm2/fmax*PLOTPDFVAR::MAX_ARROW_LENGTH);

    // In logscale, vector_norm2 = fmin*(fmax/fmin)^r <=> r = (log(vector_norm2)-log(fmin))/(log(fmax)-log(fmin))
    // Then, alength = alength_scale * r * PLOTPDFVAR::MAX_ARROW_LENGTH.

    const double arrow_head_x = r*ar*(ox-x0) + alength * ar*vector_x/vector_norm2;
    const double arrow_head_y = r*(oy-y0) + alength * vector_y/vector_norm2;

    setrgbcolor(st, vector_norm2, palette, fmin, fmax, monochrome, logscale);
    st << "RG\n";
    st << r*ar*(ox-x0) << ' ' << r*(oy-y0) << " m "; // arrow origin
    st << arrow_head_x << ' ' << arrow_head_y << " l S" << std::endl; // arrow head

    // Need fabs? Yes, if coef = alength < 0, arrows go reverse direction.
    if( fabs(alength) > AH_SIZE/2 ){
	    
	const double theta = atan2( -vector_y, -vector_x ); // reverse of arrow direction
	
	st << arrow_head_x + AH_SIZE*cos(theta-AH_ANGLE) << ' ' << arrow_head_y + AH_SIZE*sin(theta-AH_ANGLE) << " m "
	   << arrow_head_x << ' ' << arrow_head_y << " l "
	   << arrow_head_x + AH_SIZE*cos(theta+AH_ANGLE) << ' ' << arrow_head_y + AH_SIZE*sin(theta+AH_ANGLE) << " l S" << std::endl;