IrrlichtNETCP.Quaternion.Slerp C# (CSharp) Method

        public Quaternion Slerp(Quaternion q1, Quaternion q2, float time)
        {
            float angle = q1.GetDotProduct(q2);

            if (angle < 0.0f)
            {
                q1 *= -1.0f;
                angle *= -1.0f;
            }

            float scale;
            float invscale;

            if ((angle + 1.0f) > 0.05f)
            {
                if ((1.0f - angle) >= 0.05f)  // spherical interpolation
                {
                    float theta = (float)Math.Acos(angle);
                    float invsintheta = 1.0f / (float)Math.Sin(theta);
                    scale = (float)Math.Sin(theta * (1.0f - time)) * invsintheta;
                    invscale = (float)Math.Sin(theta * time) * invsintheta;
                }
                else // linear interploation
                {
                    scale = 1.0f - time;
                    invscale = time;
                }
            }
            else
            {
                q2 = new Quaternion(-q1.Y, q1.X, -q1.W, q1.Z);
                scale = (float)Math.Sin(Math.PI * (0.5f - time));
                invscale = (float)Math.Sin(Math.PI * time);
            }

            Quaternion t_tmp= (q1 * scale) + (q2 * invscale);
            this.m_x = t_tmp.X;
            this.m_y = t_tmp.Y;
            this.m_z = t_tmp.Z;
            this.m_w = t_tmp.W;
            return this;
        }