a texture(early created)cover another texture(new)

Hi , big ones~ ,I 'm back,The game I wrote (a tank shoot planes) now has get all texture rendered correctly. Thanks~
And I get a new question : For shoot , I create a class names Collimator . I render it the time the game begin,and then create many planes.
So… When I move the Collimator to the plane which I want to shoot,
the plane covers my collimator! Because as far as I know , the texture late created will cover the texture early created…
I just want to know how to set a texture shows that will never be covered?

You will have to start using the depth buffer if you don’t want to sort the objects from back to front.

Have you used a depth buffer before?

Do you mean:

I has already set .
But I don’t quite understand how these make my textures render.
Can you give more information? Thanks~!

You need a z value on each vertex. If you are looking down the negative-z axis (which probably you are in a 2D render). An object drawn with say z = -1 will always cover and object drawn with z = -2 no matter the draw order

Thanks for your help ~! I got it !
Now I know the z axis can move texture deep or out of the screen~ so the texture can cover them correctly~!