#!/bin/bash -x 

# Folders $1, $2 and $3 are required. A 3D box is created with images
# from each of the folder on two sides of the box.  Six copies of the
# box are put in a 3x2 array. Each box is also rotated in a 360 degree
# loop.

 
COUNT=1 # Name of the first image to be created
COUNT1=1 # Name of the first image in $1 to be called
COUNT2=1 # Name of the first image in $2 to be called
COUNT3=1 # Name of the first image in $3 to be called
SKIPFILES=0 # Number of files skipped due to BUG, see below.

# Total number of original files in each folder

N1=$(ls $1 | wc -l)
N2=$(ls $2 | wc -l)
N3=$(ls $3 | wc -l)

# Folder with the most images and how many
highest_number=0
for x in $N1 $N2 $N3
do
    if [ $x -gt $highest_number ] ; then
	highest_number=$x
    fi
done

OTOTAL=$highest_number

# Figure out what distance the angle will change from picture to
# picture, with the folder with the most images acting as a guide. 
# Multiply by 3 so that the motion isn't too slow.
ANG=` expr $OTOTAL / 360 \* 3`

# Make sure that the angle of change is a divisor of 360. Set tiltvalue
# so that right angles will be avoided as much as possible.
if [ $ANG -lt 3 ]; then
    ANG=3
    tiltvalue=-44
elif [ $ANG -gt 3 ] && [ $ANG -lt 6 ]; then
    ANG=6
    tiltvalue=-45
elif [ $ANG -gt 6 ] && [ $ANG -lt 9 ]; then
    ANG=9
    tiltvalue=-41
elif [ $ANG -gt 9 ] && [ $ANG -lt 12 ]; then
    ANG=12
    tiltvalue=-46
elif [ $ANG -gt 12 ]; then
    ANG=15
    tiltvalue=-40
fi

# Finds number of files needed so that the rotation stops after a
# complete rotation.
ONETURN=` expr 360 / "$ANG" `
FILES=` expr $ONETURN \* \( $OTOTAL / $ONETURN \) `


## While loop counting up to total number of files to be processed

while [ $COUNT -le $FILES ]; do

## BUG: This has to be done because files over a certain size will
## cause error if the tilt is too close to a right angle. With this
## files up to 200x200 can be processed, whereby a small skip is
## apparent in the rotation.
    if [ $tiltvalue -ge -3 -o $tiltvalue -le -87 -a $tiltvalue -ge -93 \
	-o $tiltvalue -le -177 -a $tiltvalue -ge -183 -o $tiltvalue -le \
	-267 -a $tiltvalue -ge -273 -o $tiltvalue -le -357 ]; then

## Calculating whether another revolution can be done because of files
## skipped due to BUG

	let FILES=FILES-1
	let SKIPFILES=SKIPFILES+1
	if [ $SKIPFILES -eq $ONETURN ]; then
	    let FILES=FILES+$ONETURN
	    let SKIPFILES=0
	fi

## If the tiltvalue isn't close to a right angle, we can go ahead and process
    else 
	VAR=`printf "%03d" $COUNT`

## If the files in a folder are used up before those in the other
## folders, then we loop back and process the first files in the
## respective folder. Here we give the names of the files to call: 001, 002, etc...

	if [ $COUNT1 -le $N1 ]; then
	    VAR1=$(printf "%03d" $COUNT1)
	else    VAR1=$(printf "%03d" 1)
	    COUNT1=1
	fi 

	if [ $COUNT2 -le $N2 ]; then
	    VAR2=$(printf "%03d" $COUNT2)
	else    VAR2=$(printf "%03d" 1)
	    COUNT2=1
	fi

	if [ $COUNT3 -le $N3 ]; then
	    VAR3=$(printf "%03d" $COUNT3)
	else VAR3=$(printf "%03d" 1)    
	    COUNT3=1
	fi

## The script 3Dbox is from Fred Weinhaus,
## http://www.fmwconcepts.com/imagemagick/index.html 

## 3 images at a time are made to a box. The tilt value changes during
## the course of the program.

	3Dbox pan=45 tilt=$tiltvalue pef=0.6 filter=lanczos format=center \
	mode=mirror bgcolor=transparent $1/$VAR1.png $2/$VAR2.png $3/$VAR3.png box_1.miff

## Box is copied 6 times on an image to create a 3x2 array.

	convert \( box_1.miff box_1.miff box_1.miff +append \) \( box_1.miff box_1.miff box_1.miff +append \) \
	-append $VAR.jpg

## The names for the next files to be called up or processed 
	let COUNT=COUNT+1
	let COUNT1=COUNT1+1
	let COUNT2=COUNT2+1
	let COUNT3=COUNT3+1

    fi

## Add $tiltvalue to the current angle of tilt.
    tiltvalue=`expr $tiltvalue - $ANG `
## If the angle is less than -360 degrees, return the angle to 0 degrees
    if [ $tiltvalue -lt -360 ]; then
	tiltvalue=`expr $tiltvalue + 360`

    fi

done