C# normal map rotation angle encoding to color

 public void drawNormalMapSprite(Texture2D sourceTex, Vector2 screenPoint, Rectangle sRect, float rot, Vector2 origin, Vector2 scale) {

            // Convert rotation to 0..1 range
            float rotVal = (rot % MathHelper.TwoPi) / MathHelper.TwoPi;

            // Encode rotation to color
            normalRotateColor.R = (byte)(rotVal * 255); // First approximation with 8 bits
            normalRotateColor.G = (byte)(((rotVal * 255f) % 1) * 255); // Take the remaining fractional part and scale that again to 8 bit range

            batches[(int)SpriteBatchType.spriteMainBatch].Draw(sourceTex, screenPoint, sRect, normalRotateColor, rot, origin, scale, SpriteEffects.None, 0f);

        }