#!/bin/bash

#$1 and $2 are folders for the background foto. $3 is folder for twirling photo.

#file numbers to start with
COUNT=1
COUNT1=1
COUNT2=1
COUNT3=200

# angle to start with
ANGLE=0

# start X position of picture (half of original image width + 20)
XVALUE=200
XVALUE2=200
# saves original xvalue for use in x position calculation
GVALUE=$XVALUE


# total number of original files are calculated by looking into the directories and picking the one with the most images

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

highest_number=0
for x in $N1 $N2 $N3
do
if [ $x -gt $highest_number ]
then
highest_number=$x
fi
done

#Speed up animation by only taking half the total number of files of the folder with the most files)
OTOTAL=$(echo "$highest_number / 4" | bc)

# loop to call up the files to process. calls up files numbered from 000-999 in accending order, looping all 
# directories but the one with the most files


while [ $COUNT -le $OTOTAL ]; do
    VAR=`printf "%03d" $COUNT`

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

else    VAR1=$(printf "%03d" 1)
    COUNT1=1

fi 
echo " $1 = $VAR1 "


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



else    VAR2=$(printf "%03d" 1)
    COUNT2=1


fi
echo " $2 = $VAR2 "

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

else VAR3=$(printf "%03d" 1)    
COUNT3=1

fi 
echo " $3 = $VAR3 "

#resize images from directory 1 and 2 and composites them using differences. Composites a twirling directory 3 atop which
#moves for one side of the screen to the other

convert \( \( $1/$VAR1.png -resize 720x576\! \)  \( $2/$VAR2.png -resize 720x576\! \) -compose difference -composite \
 \)  \( $3/$VAR3.png -resize 360x288\! -repage -180-144 -affine `affine_rotate $XVALUE` -transform  -compose copy \
+compose -crop 1920x1080$XVALUE2-288\! -flatten \) -compose src-over -composite $VAR.png


#add to angle so that picture rotates 360 degrees during animation
ANGLE=$(echo "scale=2; $ANGLE + 360 / $OTOTAL" | bc)


#add to x position so that the picture moves across the background during animation
#Distance to travel is total width of background plus foreground image (so it can't be seen at start and finish) 
XVALUE=$(echo "scale=2; $XVALUE - (2 * $GVALUE + 720) / $OTOTAL" | bc)

# Adds +/- symbol to xvalue
XVALUE2=`printf "%+f" $XVALUE`


#Here the speed at which the individual sequences are run through can be set.
let COUNT=COUNT+1
let COUNT1=COUNT1+1
let COUNT2=COUNT2+1
let COUNT3=COUNT3+2
done