gistfile1.lua

-- We keep a running range (min and max) values of the projection, and then use that as our shadow

function project(a, axis)
    axis = normalize(axis)
    local min = dot(a.vertices[1],axis)
    local max = min
    for i,v in ipairs(a.vertices) do
        local proj =  dot(v, axis) -- projection
        if proj < min then min = proj end
        if proj > max then max = proj end
    end

    return {min, max}
end

function contains(n, range)
    local a, b = range[1], range[2]
    if b < a then a = b; b = range[1] end
    return n >= a and n <= b
end

function overlap(a_, b_)
    if contains(a_[1], b_) then return true
    elseif contains(a_[2], b_) then return true
    elseif contains(b_[1], a_) then return true
    elseif contains(b_[2], a_) then return true
    end
    return false
end