My First Attempt at a Game...

Okay, so I've hardly ever used C++ before yesterday, but found out that using DirectX in C++ is actually quite similar to using DirectX in VB, at least, the way you blt things out and all that. So, I spent all of last night learning how to set up a C++ window and initializing DirectX and all that, and I've started on a simple space shooter.

The one thing I'm worried about is as to whether or not I'm calculating my FPS correctly. The code I'm using is as follows:

Code:

---

Frames++;
       
        if((((End.QuadPart - StartTime.QuadPart) / 500000) / 2) / 5 == 1)
        {
                FrameRate = Frames;
                QueryPerformanceCounter(&StartTime);
                Frames = 0;
        }

---

The equation in the if is just checking to see if it's been a second since start time and end time. I'm not sure if it's exactly a second or not though, is there a better way to do this?

BTW, right now I'm hitting a max FPS of 85 with 2500 moving sprites on the screen... Is this good for a C++ DirectX program?

Code:

---

bool Display(float timeDelta)
{
 
  if (Device)
  {
    //Clear back buffer to BLACK R:0 G:0 B:0 or 0x00000000
    Device->Clear(0,0,D3DCLEAR_TARGET | D3DCLEAR_ZBUFFER,d3d::BLACK,1.0f,0);
       
    //Start scene
    Device->BeginScene();
   
    //Compute FPS
    ElapsedTime+=timeDelta;
    FrameCount++;
    if (ElapsedTime>=1.0f)
    {
      FPS=(float)FrameCount/ElapsedTime;
      ElapsedTime=0.0f;
      FrameCount=0;
    }
...
...

---

Here is a screenie with 2500 asteroids, alpha blended fog (10 of em), spaceship, backdrop, and sound in the background.

I think your FPS calc is off a bit.

Of course every asteroid there is going through z rotation, scaling, rotation and rendering.

The way I do it:

Code:

---

QueryPerformanceFrequency((LARGE_INTEGER*)&freq);
while(!done)    // My maingame loop
{
    QueryPerformanceCounter((LARGE_INTEGER*)&time0);
    // Do all the stuff that should be done
    QueryPerformanceCounter((LARGE_INTEGER*)&time1);
    time = (float)(time1-time0)/(float)freq;
    fps = 1.0f/time;
}

---

freq, time0 and time1 are all __int64
time and fps are either double or float

Here is another shot with 2500 asteroids and vsync off - it seems that this is the best frame rate I can get with the engine using 2500 asteroids.

Thanks for the replies! I'll try out these other methods and see what I get then... I just added in enemies to the game and I can get about 3000 of those on the screen before I get below 50 FPS.

Try timing it with our code. That sounds little too much.

Okay, thanks for the code Shakti!

That looks like it's running pretty nice there Bubba! Looks much better than my crappy shooter, hehe.

It looks like I can actually get about 10000 sprites on the screen before I get below 30 FPS now. Of course, the sprites aren't doing anything except moving right now. My computer is very crappy too, so this is pretty good FPS for me.

I didn't realize how much faster C++ really was compared to VB :P

Oh, I have another question. How can I lock the FPS at 30? I don't want it to go above that, because it changes too much right now, and I don't want the game looking like it's running really slow at 30 FPS like it does right now.

You can lock the FPS at 30 only if the frames are above 30. If the frames go below 30 then you must remove objects until the frames are back at 30. Some sort of auto-detail system is needed for that.

Okay, so I can't just keep the FPS below 30 at all times?

Well, that would envoke timers and sleep and whatnot. Why would you want to lock the fps any way?? Look into timebased movements.

Thanks, I'll look into those.

After optimizing some code, I can get it running at 70 FPS with 10000 sprites on the screen now :)

Okay, apparently I was calculating the FPS wrong. I finally fixed it and can get 2500 sprites, along with collision detection on all of them, running at 30 FPS.

That sounds closer to reality.

I just wanted to thank this thread!

Until now, without collisions, my limit has been 300 Sprites, and then my 75FPS would start to drop.

After reading everything here, I was really hoping that my graphics card wasn't just that bad.

So I changed some of my stuff around, and can now go up to 5300 Sprites and still maintain the 75FPS. This is still without collisions and all, but thanks for letting me see how inadaquate my engine was until this point! :)

If you're curious why I was at such a loss:
- I was calling ID3DXSprite::Begin() and ID3DXSprite::End() methods for each sprite
- I switched from the D3DXSPRITE_ALPHABLEND to the D3DXSPRITE_DONOTSAVESTATE flag in the ID3DXSprite::Begin() method (since I'm not actually in need of Alpha Blending).
EDIT: This second one actually isn't a big deal since I'm not calling Begin() as many times anymore. Even with D3DXSPRITE_ALPHABLEND the FPS stay relatively the same.

And just for kicks, the FPS method I use is:

Code:

---

void UpdateFPS(void)
{
        unsigned long NewTime;
        NewTime = GetTickCount();
        if(NewTime - 1000 > LastTime)
        {
                FramesPerSecond = FramesPassed;
                FramesPassed = 0;
                LastTime = NewTime;
        }
        else
        {
                FramesPassed = FramesPassed + 1;
        }
}

---

I like this one because it doesn't have to deal with any division.

How are you doing color keying if you are not using alpha blending?

Well, so far I'm not, there isn't much use for it as of yet. Right now I'm just relying fully on my 4x4 blue texture.

Yeah I sort of put 2 and 2 together right after posting that. That's great but for non-rectangular sprites you must use alpha blending for color keying since DX9 does not have any operations that natively support color keying.

I'll make sure to keep it in mind. Later on I'm definitely going to have to use alpha-blending once I want to move away from the cheapest graphics I can come up with :)