collision velocity fixing

local function resolveDynamically(b1, b2)

    -- Distance between balls
    --local fDistance = um.distance(b1.px, b1.py, b2.px, b2.py)
    local fDistance = math.sqrt((b1.px - b2.px)*(b1.px - b2.px) + (b1.py - b2.py)*(b1.py - b2.py));

    -- Normal
    local nx = (b2.px - b1.px) / fDistance;
    local ny = (b2.py - b1.py) / fDistance;

    -- Tangent
    local tx = -ny;
    local ty = nx;

    -- Dot Product Tangent
    local dpTan1 = b1.vx * tx + b1.vy * ty;
    local dpTan2 = b2.vx * tx + b2.vy * ty;

    -- Dot Product Normal
    local dpNorm1 = b1.vx * nx + b1.vy * ny;
    local dpNorm2 = b2.vx * nx + b2.vy * ny;

    -- Conservation of momentum in 1D
    local m1 = (dpNorm1 * (b1.weight - b2.weight) + 2.0 * b2.weight * dpNorm2) / (b1.weight + b2.weight);
    local m2 = (dpNorm2 * (b2.weight - b1.weight) + 2.0 * b1.weight * dpNorm1) / (b1.weight + b2.weight);

    local b1Speed = math.sqrt(b1.vx ^ 2 + b1.vy ^ 2)
    local b2Speed = math.sqrt(b2.vx ^ 2 + b2.vy ^ 2)
    local precol = b1Speed + b2Speed
    print("total speed: " .. precol)
    -- Update ball velocities
    b1.vx = tx * dpTan1 + nx * m1;
    b1.vy = ty * dpTan1 + ny * m1;
    b2.vx = tx * dpTan2 + nx * m2;
    b2.vy = ty * dpTan2 + ny * m2;
    b1Speed = math.sqrt(b1.vx ^ 2 + b1.vy ^ 2)
    b2Speed = math.sqrt(b2.vx ^ 2 + b2.vy ^ 2)
    local postcol = b1Speed + b2Speed
    print("total speed: " .. postcol)
end