Discussions

@AdamSpeight2008:

(b^2 * t * P1):

b^2 = (3*(1-t))^2 = 9(1-t)^2 instead of 3(1-t)^2

so it should be (3 * a^2 * t * P1) imho

1 hour ago, Minh wrote

Tokter,

Looking more into it, your routine isn't a direct reflection of this formula:

Can you point me to how you worked that out?

First you get the extended form of your formula http://www.wolframalpha.com/input/?i=%281-t%29%5E3*P0%2B3*%281-t%29%5E2*t*P1%2B3*%281-t%29*t%5E2*P2%2Bt%5E3*P3:

-P0*t^3 + 3*P0*t^2 - 3*P0*t + P0 + 3*P1*t^3 - 6*P1*t^2 + 3*P1*t - 3*P2*t^3 + 3*P2*t^2 + P3*t^3

Then you factorize for t^3, t^2 and t

t^3(-P0 + 3*P1 - 3*P2 + P3) + t^2(3*P0 - 6*P1 + 3*P2) + t(3*P1 - 3* P0) + P0

then you substitute:

c = 3*(P1 - P0)
b = 3*(P2 - P1) - c
a = P3 - P0 - c -b

And you get:

B(t) = (a * t^3) + (b * t^2) + (c * t) + P0

        public PointF CubicBezier(float t, PointF p0, PointF p1, PointF p2, PointF p3)
        {
            float cx = 3 * (p1.X - p0.X);
            float bx = 3 * (p2.X - p1.X) - cx;
            float ax = p3.X - p0.X - cx - bx;
            float cy = 3 * (p1.Y - p0.Y);
            float by = 3 * (p2.Y - p1.Y) - cy;
            float ay = p3.Y - p0.Y - cy - by;
            float tCubed = t * t * t;
            float tSquared = t * t;
            float resultX = (ax * tCubed) + (bx * tSquared) + (cx * t) + p0.X;
            float resultY = (ay * tCubed) + (by * tSquared) + (cy * t) + p0.Y;
            return new PointF(resultX, resultY);
        }

That's how I would do it:

        private Color ColorLerp(Color a, Color b, float l)
        {
            return Color.FromArgb(
                (int)((float)a.A + ((float)b.A - (float)a.A) * l),
                (int)((float)a.R + ((float)b.R - (float)a.R) * l),
                (int)((float)a.G + ((float)b.G - (float)a.G) * l),
                (int)((float)a.B + ((float)b.B - (float)a.B) * l)
                );
        }

There is nothing new about that riddle

The hotel has $25 + the mailman has $2 = $27 that the friends payed.

The video is well made, but the iA app looks completely useless to me.

@spivonious:Nothing has been announced regarding the future of XNA.

That was really cool, I hope we get that for XNA too!

Still not a fair comparison. You would have to take a look cradle to cradle. Then the hummer would be more environmentally friendly then a Prius.

This study, done by a marketing firm, has been debunked so many times. I can't believe people still believe that...

@W3bbo:For what it's worth. Using Sql2005 on my dev machine (so no network involved).

Using your method, but within a transaction, it inserts 15,000 records in 3s.

            var start = DateTime.Now;
            using (SqlConnection con = GetConnection())
            {
                var tran = con.BeginTransaction();
                SqlCommand cmd = con.CreateCommand();
                cmd.Transaction = tran;
                cmd.CommandText = "insert into test (value) values (@value)";
                cmd.Parameters.Add("@value", SqlDbType.Int);

                foreach (int r in recordsToInsert)
                {
                    cmd.Parameters["@value"].Value = r;
                    cmd.ExecuteNonQuery();
                }
                tran.Commit();
            }
            var end = DateTime.Now;
            tbOutput.Text = string.Format("Elapsed time {0}", (end - start));

Using a stored procedure and batching all 15,000 inserts into one command, about 0.4s

            var start = DateTime.Now;
            using (SqlConnection con = GetConnection())
            {
                var tran = con.BeginTransaction();
                SqlCommand cmd = con.CreateCommand();
                cmd.Transaction = tran;
                var sb = new StringBuilder();
                foreach (int r in recordsToInsert)
                {
                    sb.AppendFormat("exec Insert_Test {0};", r);
                }
                cmd.CommandText = sb.ToString();
                cmd.ExecuteNonQuery();
                tran.Commit();
            }
            var end = DateTime.Now;
            tbOutput.Text = string.Format("Elapsed time {0}", (end - start));