Can any one help me find the problem why my sprite texture does not resize with the window when I resize the window the sprite texture size or scale does not change according to the window size

directx does not scale sprites to the window size for you. if your window size changes, you must draw at new positions and scales to compensate.

getting your sprites to scale automatically with the window size is called "resolution independent graphics".

to do resolution independent graphics, you use a virtual coordinate system, such as 10,000x10,000, and make all your draw calls using those. then inside your drawing routines, you convert those to screen coordinates based on the current size of the window:

screen_x= (screen_width-1) * virtual_x / 9999 // i think i got that right.... <g>

screen_y= (screen_height-1) * virtual_y / 9999

so you say something like drawsprite(sprite_num,5000,5000,6000,6000) and it always draws the sprite with the upper left corner in the middle of the window, and the size of the sprite is always 1/10 the width and 1/10th the height of the window. 5000 to 6000 is 1000 virtual pixels, and 1000 is 1/10th of 10,000, the virtual width of the window.

Well, in your new engine you handle WM_SIZE and resize the back buffer accordingly. Thus the sprite sizes stay the same.

In the anti virus game there is no WM_SIZE handler, the back buffer size does not change. In that case Direct3d automatically scales the backbuffer to the window size (and thusly the sprite sizes change).

Actually the way of the new engine feels cleaner. I have no experience with the sprite system, but you should be able to use a ortho matrix as projection matrix to implement a virtual screen size. Set the ortho width/height to a fixed size irregardless the back buffer size. I'm not sure however if the ID3DXSprites use pretransformed vertices. If they do, you have to use the way Norman Barrows explained.

the method i described is for when the back buffer size changes in full screen mode.

in windowed mode (which i don't use and am not that familiar with), i believe there's a presentation mode that will do a stretch-blit to the window's client area. this would scale everything automatically, at the cost of a stretch-blit every frame.

stretch-blit is one method to get resolution independent graphics in full screen mode, but due to the extra overhead of the stretch-blit every frame, some consider it poor practice.

Do not use WM_SIZE to check for a lost device. There are other methods to loose a device (lock the computer, etc.).

Simply check the return value of PresentScene (D3DERR_DEVICELOST).

http://msdn.microsoft.com/en-us/library/windows/desktop/bb174714(v=vs.85).aspx nicely describes the usual issues.