Programming

i need to check the corner collisions but when the die start settling and an entire edge comes close to the floor, gravity keeps pulling back on several of them making them bounce back just a tiny bit, not reaching the velocity that gets rounded to zero.

I fixed that on the current version doe!

that's one of the aspects of the current implementation

I didn't have the patience to do it myself bit wanted to see just how complex it would get:

fp32_mul() {
    local a=$1 b=$2
    local sa=$(( (a >> 31) & 1 ))
    local sb=$(( (b >> 31) & 1 ))
    local sign=$((sa ^ sb))

    local ea=$(( (a >> 23) & 0xff ))
    local eb=$(( (b >> 23) & 0xff ))
    local fa=$(( a & 0x7fffff ))
    local fb=$(( b & 0x7fffff ))

    # NaN / infinity / zero handling
    if (( ea == 255 )); then
        if (( fa != 0 )); then
            printf '%08x\n' $((0x7fc00000))
            return
        fi
        if (( eb == 0 && fb == 0 )); then
            printf '%08x\n' $((0x7fc00000))   # inf * 0 = NaN
            return
        fi
        printf '%08x\n' $(((sign << 31) | 0x7f800000))
        return
    fi

    if (( eb == 255 )); then
        if (( fb != 0 )); then
            printf '%08x\n' $((0x7fc00000))
            return
        fi
        if (( ea == 0 && fa == 0 )); then
            printf '%08x\n' $((0x7fc00000))
            return
        fi
        printf '%08x\n' $(((sign << 31) | 0x7f800000))
        return
    fi

    if (( ea == 0 && fa == 0 || eb == 0 && fb == 0 )); then
        printf '%08x\n' $((sign << 31))
        return
    fi

    # Convert subnormals to a normalized significand/exponent.
    # m is a 24-bit significand for normals.
    local ma mb
    if (( ea == 0 )); then
        ma=$fa
        ea=1
        while (( (ma & 0x800000) == 0 )); do
            ma=$((ma << 1))
            ((ea--))
        done
    else
        ma=$((fa | 0x800000))
    fi

    if (( eb == 0 )); then
        mb=$fb
        eb=1
        while (( (mb & 0x800000) == 0 )); do
            mb=$((mb << 1))
            ((eb--))
        done
    else
        mb=$((fb | 0x800000))
    fi

    # Multiply the two 24-bit significands.
    # Product is up to 48 bits.
    local p=$((ma * mb))
    local e=$((ea + eb - 127))

    # Normalize product.
    #
    # ma*mb has binary point after bit 46.  If bit 47 is set,
    # product is [2,4), otherwise [1,2).
    local shift
    if (( p & 0x800000000000 )); then
        shift=24
        ((e++))
    else
        shift=23
    fi

    # Extract 23 fraction bits plus guard/round/sticky information.
    local frac=$(( (p >> shift) & 0x7fffff ))
    local guard=$(( (p >> (shift - 1)) & 1 ))
    local round=$(( (p >> (shift - 2)) & 1 ))
    local sticky=0

    if (( shift >= 3 )); then
        local mask=$(( (1 << (shift - 2)) - 1 ))
        (( (p & mask) != 0 )) && sticky=1
    fi

    # Round-to-nearest, ties-to-even.
    if (( guard && (round || sticky || (frac & 1)) )); then
        ((frac++))
        if (( frac == 0x800000 )); then
            frac=0
            ((e++))
        fi
    fi

    # Overflow -> infinity.
    if (( e >= 255 )); then
        printf '%08x\n' $(((sign << 31) | 0x7f800000))
        return
    fi

    # Normal result.
    if (( e > 0 )); then
        printf '%08x\n' $(((sign << 31) | (e << 23) | frac))
        return
    fi

    # Underflow into the subnormal range.
    #
    # At this point the normalized significand represented by
    # (1.frac) must be shifted right by 1-e positions.
    local mant=$((0x800000 | frac))
    local rshift=$((1 - e))
    local lost=0
    local halfway=0
    local low=0

    if (( rshift >= 25 )); then
        # Everything rounds to zero (unless the exact value is
        # sufficiently close, which it cannot be here).
        mant=0
    else
        low=$((mant & ((1 << rshift) - 1)))
        mant=$((mant >> rshift))

        halfway=$((1 << (rshift - 1)))

        if (( low > halfway || (low == halfway && (mant & 1)) )); then
            ((mant++))
        fi
    fi

    # Rounding a subnormal can produce the smallest normal.
    if (( mant >= 0x800000 )); then
        printf '%08x\n' $(((sign << 31) | (1 << 23)))
    else
        printf '%08x\n' $(((sign << 31) | mant))
    fi
}