triforce.sh

#!/usr/bin/env bash

[ -z "$*" -o "$*" = "help" ] && echo triforce.sh [layer] [height]
[ "$1" -eq "$1" ] 2>/dev/null && l=$1 || l=2 # layers to generate
[ "$2" -eq "$2" ] 2>/dev/null && h=$2 || h=5 # height of individual triangle

rptchar() {
    local iter char
    char=$1 # must be single char
    iter=$2 # must be integer

    if [ $iter -le 0 ]; then
        return 0
    elif [ $iter -le 4500 ]; then
        eval printf "%.s$char" {1..$iter} # uses eval
    else
        printf '%*s' $iter | tr ' ' "$char"
    fi
}

for ((k=1;k<=$l;k++)); do

    # generate triangles for a single layer
    for ((i=1;i<=$h;i++)); do

        # generate initial padding for triangles
        # comment out for the true triforce effect
        rptchar '\ ' $((h * (l - k)))

        # generate the initial triangle
        rptchar '\ ' $((h - i))
        rptchar '*' $((2 * i - 1))

        # generate the other triangles
        for ((j=2;j<=$k;j++)); do # does not execute when k=1
            rptchar '\ ' $((2 * (h - i + 1) - 1))
            rptchar '*' $((2 * i - 1))
        done

        printf "\n"
    done
done