#======================================================================

#                    R D I _ C O O R D S . P L 

#                    doc: Sun Jan 19 17:57:53 2003

#                    dlm: Sun May 23 22:47:32 2010

#                    (c) 2003 A.M. Thurnherr

#                    uE-Info: 28 74 NIL 0 0 72 2 2 4 NIL ofnI

#======================================================================

# RDI Workhorse Coordinate Transformations

# HISTORY:

#	Jan 19, 2003: - written

#	Jan 21, 2003: - made it obey HEADING_BIAS (magnetic declination)

#	Jan 22, 3003: - corrected magnetic declination

#	Feb 16, 2003: - use pitch correction from RDI manual

#	Oct 11, 2003: - BUG: return value of atan() had been interpreted

#					     as degrees instead of radians

#	Feb 27, 2004: - added velApplyHdgBias()

#				  - changed non-zero HEADING_ALIGNMENT from error to warning

#	Sep 16, 2005: - added deg() for [mkprofile]

#	Aug 26, 2006: - BUG: incorrect transformation for uplookers

#	Nov 30, 2007: - optimized &velInstrumentToEarth(), velBeamToInstrument()

#				  - added support for 3-beam solutions

#	Feb 12, 2008: - added threeBeamFlag

#	Mar 18, 2009: - added &gimbal_pitch(), &angle_from_vertical()

#	May 19, 2009: - added &velBeamToVertical()

#	May 23, 2009: - debugged & renamed to &velBeamToBPEarth

#	May 23, 2010: - changed prototypes of rad() & deg() to conform to ANTS

use strict;

use POSIX;

my($PI) = 3.14159265358979;

sub rad(@) { return $_[0]/180 * $PI; }

sub deg(@) { return $_[0]/$PI * 180; }

$RDI_Coords::minValidVels = 3;			# 3-beam solutions ok

$RDI_Coords::threeBeam_1 = 0;			# stats

$RDI_Coords::threeBeam_2 = 0;

$RDI_Coords::threeBeam_3 = 0;

$RDI_Coords::threeBeam_4 = 0;

$RDI_Coords::fourBeam    = 0;

$RDI_Coords::threeBeamFlag = 0;			# flag last transformation

{ # STATIC SCOPE

	my(@B2I);

	sub velBeamToInstrument(@)

	{

		my($dta,$v1,$v2,$v3,$v4) = @_;

		return undef unless (defined($v1) + defined($v2) +

					   		 defined($v3) + defined($v4)

								>= $RDI_Coords::minValidVels);

		unless (defined(@B2I)) {

#			print(STDERR "RDI_Coords::minValidVels = $RDI_Coords::minValidVels\n");

			my($a) = 1 / (2 * sin(rad($dta->{BEAM_ANGLE})));

			my($b) = 1 / (4 * cos(rad($dta->{BEAM_ANGLE})));

			my($c) = $dta->{CONVEX_BEAM_PATTERN} ? 1 : -1;

			my($d) = $a / sqrt(2);

			@B2I = ([$c*$a,	-$c*$a,	0,		0	 ],

				    [0,		0,		-$c*$a,	$c*$a],

				    [$b,	$b,		$b,		$b	 ],

				    [$d,	$d,		-$d,	-$d	 ]);

#			print(STDERR "@{$B2I[0]}\n@{$B2I[1]}\n@{$B2I[2]}\n@{$B2I[3]}\n");

		}

		if (!defined($v1)) {					# 3-beam solutions

			$RDI_Coords::threeBeamFlag = 1;

			$RDI_Coords::threeBeam_1++;

			$v1 = -($v2*$B2I[3][1]+$v3*$B2I[3][2]+$v4*$B2I[3][3])/$B2I[3][0];

		} elsif (!defined($v2)) {

			$RDI_Coords::threeBeamFlag = 1;

			$RDI_Coords::threeBeam_2++;

			$v2 = -($v1*$B2I[3][0]+$v3*$B2I[3][2]+$v4*$B2I[3][3])/$B2I[3][1];

		} elsif (!defined($v3)) {

			$RDI_Coords::threeBeamFlag = 1;

			$RDI_Coords::threeBeam_3++;

			$v3 = -($v1*$B2I[3][0]+$v2*$B2I[3][1]+$v4*$B2I[3][3])/$B2I[3][2];

		} elsif (!defined($v4)) {

			$RDI_Coords::threeBeamFlag = 1;

			$RDI_Coords::threeBeam_4++;

			$v4 = -($v1*$B2I[3][0]+$v2*$B2I[3][1]+$v3*$B2I[3][2])/$B2I[3][3];

		} else {

			$RDI_Coords::threeBeamFlag = 0;

			$RDI_Coords::fourBeam++;

		}

		return ($v1*$B2I[0][0]+$v2*$B2I[0][1],

				$v3*$B2I[1][2]+$v4*$B2I[1][3],

				$v1*$B2I[2][0]+$v2*$B2I[2][1]+$v3*$B2I[2][2]+$v4*$B2I[2][3],

				$v1*$B2I[3][0]+$v2*$B2I[3][1]+$v3*$B2I[3][2]+$v4*$B2I[3][3]);

	}

} # STATIC SCOPE

{ # STATIC SCOPE

	my($hdg,$pitch,$roll,@I2E);

	sub velInstrumentToEarth(@)

	{

		my($dta,$ens,$v1,$v2,$v3,$v4) = @_;

		return undef unless (defined($v1) && defined($v2) &&

					   		 defined($v3) && defined($v4));

		unless (@I2E &&

				$hdg   == $dta->{ENSEMBLE}[$ens]->{HEADING}

							- $dta->{HEADING_BIAS} &&

				$pitch == $dta->{ENSEMBLE}[$ens]->{PITCH} &&

				$roll  == $dta->{ENSEMBLE}[$ens]->{ROLL}) {

			printf(STDERR "$0: warning HEADING_ALIGNMENT == %g ignored\n",

						  $dta->{HEADING_ALIGNMENT})

				if ($dta->{HEADING_ALIGNMENT});

			$hdg   = $dta->{ENSEMBLE}[$ens]->{HEADING} - $dta->{HEADING_BIAS};

			$pitch = $dta->{ENSEMBLE}[$ens]->{PITCH};

			$roll  = $dta->{ENSEMBLE}[$ens]->{ROLL};

			my($rad_gimbal_pitch) = atan(tan(rad($pitch)) * cos(rad($roll)));

			my($sh,$ch) = (sin(rad($hdg)),	cos(rad($hdg)));

			my($sp,$cp) = (sin($rad_gimbal_pitch),cos($rad_gimbal_pitch));

			my($sr,$cr) = (sin(rad($roll)),	cos(rad($roll)));

			@I2E = $dta->{ENSEMBLE}[$ens]->{XDUCER_FACING_UP}

				 ? (

					[-$ch*$cr-$sh*$sp*$sr,	$sh*$cp,-$ch*$sr+$sh*$sp*$cr],

					[-$ch*$sp*$sr+$sh*$cr,	$ch*$cp, $sh*$sr+$ch*$sp*$cr],

					[+$cp*$sr,				$sp,	-$cp*$cr,			],

				 ) : (

					[$ch*$cr+$sh*$sp*$sr,	$sh*$cp, $ch*$sr-$sh*$sp*$cr],

					[$ch*$sp*$sr-$sh*$cr,	$ch*$cp,-$sh*$sr-$ch*$sp*$cr],

					[-$cp*$sr,				$sp,	 $cp*$cr,			],

				 );

		}

		return ($v1*$I2E[0][0]+$v2*$I2E[0][1]+$v3*$I2E[0][2],

				$v1*$I2E[1][0]+$v2*$I2E[1][1]+$v3*$I2E[1][2],

				$v1*$I2E[2][0]+$v2*$I2E[2][1]+$v3*$I2E[2][2],

				$v4);

	}

} # STATIC SCOPE

#======================================================================

# velBeamToBPEarth3(@) calculates the vertical- and horizontal vels

# from the two beam pairs separately. Note that (w1+w2)/2 is 

# identical to the w estimated according to RDI without 3-beam 

# solutions.

#======================================================================

{ # STATIC SCOPE

	my($TwoCosBAngle,$TwoSinBAngle);

	sub velBeamToBPEarth(@)

	{

		my($dta,$ens,$b1,$b2,$b3,$b4) = @_;

		my($v12,$w12,$v34,$w34);

		return (undef,undef,undef,undef)

			unless defined($b1) && defined($b2) && defined($b3) && defined($b4);

		unless (defined($TwoCosBAngle)) {

			$TwoCosBAngle = 2 * cos(rad($dta->{BEAM_ANGLE}));

			$TwoSinBAngle = 2 * sin(rad($dta->{BEAM_ANGLE}));

		}

		my($roll)  = rad($dta->{ENSEMBLE}[$ens]->{ROLL});							

		my($sr) = sin($roll); my($cr) = cos($roll);

		my($pitch) = atan(tan(rad($dta->{ENSEMBLE}[$ens]->{PITCH})) * $cr);	# gimbal pitch

		my($sp) = sin($pitch); my($cp) = cos($pitch);

		# Sign convention:

		#	- refer to Coord manual Fig. 3

		#	- v12 is horizontal velocity from beam1 to beam2, i.e. westward for upward-looking ADCP

		#	  with beam 3 pointing north (heading = 0)

		#	- w is +ve upward, regardless of instrument orientation

		my($v12_ic) = ($b1-$b2)/$TwoSinBAngle;							# instrument coords with w vertical up

		my($w12_ic) = ($b1+$b2)/$TwoCosBAngle;

		$w12_ic *= -1 if ($dta->{ENSEMBLE}[$ens]->{XDUCER_FACING_UP});

		my($v34_ic) = ($b3-$b4)/$TwoSinBAngle;

		my($w34_ic) = ($b3+$b4)/$TwoCosBAngle;

		$w34_ic *= -1 if ($dta->{ENSEMBLE}[$ens]->{XDUCER_FACING_UP});

		if ($dta->{ENSEMBLE}[$ens]->{XDUCER_FACING_UP}) {				# beampair Earth coords

			$w12 = $w12_ic*$cr + $v12_ic*$sr - $v34_ic*$sp;

			$v12 = $v12_ic*$cr - $w12_ic*$sr + $w34_ic*$sp;

			$w34 = $w34_ic*$cp - $v34_ic*$sp + $v12_ic*$sr;

    	    $v34 = $v34_ic*$cp + $w34_ic*$sp - $w12_ic*$sr;

		} else {

			$w12 = $w12_ic*$cr - $v12_ic*$sr - $v34_ic*$sp;

			$v12 = $v12_ic*$cr + $w12_ic*$sr + $w34_ic*$sp;

			$w34 = $w34_ic*$cp - $v34_ic*$sp - $v12_ic*$sr;

        	$v34 = $v34_ic*$cp + $w34_ic*$sp + $w12_ic*$sr;

		}

		return ($v12,$w12,$v34,$w34);

	}

}

#======================================================================

# velApplyHdgBias() applies the heading bias, which is used to correct

# for magnetic declination for data recorded in Earth-coordinates ONLY.

# Bias correction for beam-coordinate data is done in velInstrumentToEarth()

#======================================================================

{ # STATIC SCOPE

	my($sh,$ch);

	sub velApplyHdgBias(@)

	{

		my($dta,$ens,$v1,$v2,$v3,$v4) = @_;

		return undef unless (defined($v1) && defined($v2));

		unless (defined($sh)) {

			printf(STDERR "$0: warning HEADING_ALIGNMENT == %g ignored\n",

						  $dta->{HEADING_ALIGNMENT})

				if ($dta->{HEADING_ALIGNMENT});

			$sh = sin(rad(-$dta->{HEADING_BIAS}));

			$ch = cos(rad(-$dta->{HEADING_BIAS}));

		}

		return ( $v1*$ch + $v2*$sh,

				-$v1*$sh + $v2*$ch,

				 $v3              ,

				 $v4              );

	}

} # STATIC SCOPE

#----------------------------------------------------------------------

# Pitch/Roll Functions

#----------------------------------------------------------------------

sub gimbal_pitch($$)	# RDI coord trans manual

{

	my($tilt1,$tilt2) = @_;

	return deg(atan(tan(rad($tilt1)) * cos(rad($tilt2))));

}

# - angle from vertical is home grown and should be treated with caution

# - angle between two unit vectors given by acos(v1 dot v2)

# - vertical unit vector v1 = (0 0 1) => dot product = z-component of v2

# - when vertical unit vector is pitched in x direction, followed by

#	roll in y direction:

#		x = sin(pitch)

#		y = cos(pitch) * sin(roll)

#		z = cos(pitch) * cos(roll)

#			has been checked with sqrt(x^2+y^2+z^2) == 1

# - for small angles, this is very similar to sqrt(pitch^2+roll^2)

sub angle_from_vertical($$)

{

	my($tilt1,$tilt2) = @_;

	my($rad_pitch) = atan(tan(rad($tilt1)) * cos(rad($tilt2)));

	return deg(acos(cos($rad_pitch) * cos(rad($tilt2))));

}

1;