XNA 2D rotated sprite, with realative rotated position (Lunar Lander Exhaust Placement) - xna

Question

I am making a little Lunar Lander clone, and its working quite ok, now i have added particle effects to the lander, so when the thrust is engange, the particle effect is created, just in the middle of my ship.
What i would like to have happen is that the Particles are created, where the ship exhaust is on the sprite. And this has me stumped. I know i should be able to calculate it, as i both have the rotation angle and the current location, so i should be able to get the rotated location of any pixel within my 64x64 sprite.
Im interested in calculating the Lander.exhaust.X and Lander.exhaust.Y values. Could anyone point me in the right direction.
//this is part of the code, im sure i dont need all of it :)
Lander.acceleration.X = Lander.acceleration.X * (0.01f * gameTime.ElapsedGameTime.Seconds);
Lander.acceleration.Y = Lander.acceleration.Y * (0.01f * gameTime.ElapsedGameTime.Seconds);
Lander.velocity.Y = Lander.velocity.Y + (0.05f + Lander.velocity.Y * gameTime.ElapsedGameTime.Seconds);
Lander.oldvelocity.X = Lander.velocity.X;
Lander.oldvelocity.Y = Lander.velocity.Y;
Lander.exhaust.X = (float)Math.Cos(Lander.RotationAngle) * 0.1f + Lander.Position.Y ;
Lander.exhaust.Y = (float)Math.Sin(Lander.RotationAngle) * 0.1f + Lander.Position.X ;
Lander.Position.Y = Lander.velocity.Y + Lander.Position.Y;
Lander.Position.X = Lander.velocity.X + Lander.Position.X;
//if (Lander.Position.Y >= groundlevel + (Lander.mSpriteTexture.Height / 2))
if (Lander.Position.Y >= groundlevel)
{
Lander.Position.Y = groundlevel;
Lander.velocity.X = 0f;
Lander.oldvelocity.X = 0f;
}
float circle = MathHelper.Pi * 2;
RotationAngle = RotationAngle % circle;
Lander.RotationAngle = RotationAngle;
RotationAngledegrees = MathHelper.ToDegrees(RotationAngle);
if (keyState.IsKeyDown(Keys.Space))
{
Lander.acceleration.X = (float)Math.Cos(Lander.RotationAngle) * 0.1f + Lander.acceleration.X;
Lander.acceleration.Y = (float)Math.Sin(Lander.RotationAngle) * 0.1f + Lander.acceleration.Y;
Lander.velocity.X = Lander.oldvelocity.X + Lander.acceleration.X;
Lander.velocity.Y = Lander.oldvelocity.Y + Lander.acceleration.Y;
particleEngine.EmitterLocation = new Vector2(Lander.exhaust.X, Lander.exhaust.Y);
-lasse

Answer 1

Lander.exhaust.X = (float)Math.Cos(RotationAngle) * 32 + Lander.Position.X;
Lander.exhaust.Y = (float)Math.Sin(RotationAngle) * 32 + Lander.Position.Y;
You may have to subtract or add PI/2 to the angle depending on the initial angle of the sprite the emitter will be 32 pixels away from the position of the Lander.
On a side note, it would probably be a good idea to put each part of the game in its own class, it will make changing stuff later a LOT easier.
And another thing, when you add the velocity to the position, you can do this:
Lander.Position += Lander.velocity;
It basically does the same thing.