xmpp.chapril.org-ejabberd/tools/captcha.sh

#!/bin/sh

INPUT=$1

WAVE1_AMPLITUDE=$((2 + $RANDOM % 5))
WAVE1_LENGTH=$((50 + $RANDOM % 25))
WAVE2_AMPLITUDE=$((2 + $RANDOM % 5))
WAVE2_LENGTH=$((50 + $RANDOM % 25))
WAVE3_AMPLITUDE=$((2 + $RANDOM % 5))
WAVE3_LENGTH=$((50 + $RANDOM % 25))
W1_LINE_START_Y=$((10 + $RANDOM % 40))
W1_LINE_STOP_Y=$((10 + $RANDOM % 40))
W2_LINE_START_Y=$((10 + $RANDOM % 40))
W2_LINE_STOP_Y=$((10 + $RANDOM % 40))
W3_LINE_START_Y=$((10 + $RANDOM % 40))
W3_LINE_STOP_Y=$((10 + $RANDOM % 40))

B1_LINE_START_Y=$(($RANDOM % 40))
B1_LINE_STOP_Y=$(($RANDOM % 40))
B2_LINE_START_Y=$(($RANDOM % 40))
B2_LINE_STOP_Y=$(($RANDOM % 40))
#B3_LINE_START_Y=$(($RANDOM % 40))
#B3_LINE_STOP_Y=$(($RANDOM % 40))

B1_LINE_START_X=$(($RANDOM % 20))
B1_LINE_STOP_X=$((100 + $RANDOM % 40))
B2_LINE_START_X=$(($RANDOM % 20))
B2_LINE_STOP_X=$((100 + $RANDOM % 40))
#B3_LINE_START_X=$(($RANDOM % 20))
#B3_LINE_STOP_X=$((100 + $RANDOM % 40))

ROLL_X=$(($RANDOM % 40))

convert -size 180x60 xc:none -pointsize 40 \
	\( -clone 0 -fill white \
	-stroke black -strokewidth 4 -annotate +0+40 "$INPUT" \
	-stroke white -strokewidth 2 -annotate +0+40 "$INPUT" \
	-roll +$ROLL_X+0 \
	-wave "$WAVE1_AMPLITUDE"x"$WAVE1_LENGTH" \
	-roll -$ROLL_X+0 \) \
	\( -clone 0 -stroke black \
	-strokewidth 1 -draw \
	"line $B1_LINE_START_X,$B1_LINE_START_Y $B1_LINE_STOP_X,$B1_LINE_STOP_Y" \
	-strokewidth 1 -draw \
	"line $B2_LINE_START_X,$B2_LINE_START_Y $B2_LINE_STOP_X,$B2_LINE_STOP_Y" \
	-wave "$WAVE2_AMPLITUDE"x"$WAVE2_LENGTH" \) \
	\( -clone 0 -stroke white \
	-strokewidth 2 -draw "line 0,$W1_LINE_START_Y 140,$W1_LINE_STOP_Y" \
	-strokewidth 2 -draw "line 0,$W2_LINE_START_Y 140,$W2_LINE_STOP_Y" \
	-strokewidth 2 -draw "line 0,$W3_LINE_START_Y 140,$W3_LINE_STOP_Y" \
	-wave "$WAVE3_AMPLITUDE"x"$WAVE3_LENGTH" \) \
	-flatten -crop 140x60 +repage -quality 90 -depth 8 png:-