how can I make a bullet tail effect

Not enough info.
What rendering engine are you using?
What language are you using?

no engine
java or as

I made a smoke tail for firing rockets, but it's not the same as your image. It was like this:


Basically, I just got a smoke image, and draw one every frame where the end of the rocket is, and I made every old smoke a little more translucent (by decreasing the alpha value). After a short amount of time, I removed the smoke entirely. So, that's an option.

I said rendering engine, ie OpenGL, SDL, directX etc, not full game engine. What API is it your using to draw the graphics basically.

For 2d graphics simply leaving a smoke sprite behind when you redraw a projectile in a new location works fine.

You probably want to look into the concept of "particle systems" -- at a basic level you can get some very good effects simply by leaving a "trail" of sprites and having them fade (i.e. become more transparent) over time. If you apply "additive blending" to your particles you can get an effect where they glow brightly when clustered together immediately behind your rocket and get less bright as they separate and become more transparent further behind it.

That should give you a couple of terms to search for -- does that help you to get started? There appear to be plenty of tutorials if you search for one that looks suitable for your needs.

If you want a limited-length tail tat follows the bullet, a sprite comprising the whole tail and possibly the bullet in front of it (rendered as a billboard facing the camera) should be simple and efficient.
You can stretch it to show its growth at the start of bullet movement, animate texture coordinates or shader parameters to make it disappear, break it into more than two triangles to manipulate texture coordinates flexibly, and so on.
The art, for example (your reference picture) a ball on transparent background that fades from solid off-white pink at the front to semi-transparent dark orange at the back, should be easier to make than very transparent particle sprites.

I made a smoke tail for firing rockets, but it's not the same as your image. It was like this:


Basically, I just got a smoke image, and draw one every frame where the end of the rocket is, and I made every old smoke a little more translucent (by decreasing the alpha value). After a short amount of time, I removed the smoke entirely. So, that's an option.

thanks
I can not get the image ,can you gave me a link
and I worry about it is efficient ?

I said rendering engine, ie OpenGL, SDL, directX etc, not full game engine. What API is it your using to draw the graphics basically.

For 2d graphics simply leaving a smoke sprite behind when you redraw a projectile in a new location works fine.

sorry for my description is not clear

It's 2d graphic on flash player or java

[quote name='BeerNutts' timestamp='1344885885' post='4969168']
I made a smoke tail for firing rockets, but it's not the same as your image. It was like this:


Basically, I just got a smoke image, and draw one every frame where the end of the rocket is, and I made every old smoke a little more translucent (by decreasing the alpha value). After a short amount of time, I removed the smoke entirely. So, that's an option.

thanks
I can not get the image ,can you gave me a link
and I worry about it is efficient ?
[/quote]

Here's the link to the source image: Image

As far as efficiency, there won't be any (negligible) difference than having one large image with the tail that keeps moving really. It'll be using the same Sprite, just with varying alpha values. Obviously, you can increase or decrease the tail length if you are concerned about it.