How do you Check Boundary Collision?

HelloWorld · #1 (**permalink**) 09-17-2007, 01:08 AM

PHP Code:

              int MaxX = ScreenManager.GraphicsDevice.Viewport.Width - 50;

            int MinX = 0;

 
            int MaxY = ScreenManager.GraphicsDevice.Viewport.Height - 50;

            int MinY = 0;

For some reason, the Max, and Min Y doesn't work... But Max X, and Min X works fine, though I need to adjust the value... Please help me on this, I'm trying to detect boundary collision in the full screen game... thanx in advance

Here's the full method:

PHP Code:

          public void CheckBoundaryCollision()

        {

            int MaxX = ScreenManager.GraphicsDevice.Viewport.Width - 50;

            int MinX = 0;

 
            int MaxY = ScreenManager.GraphicsDevice.Viewport.Height - 50;

            int MinY = 0;

 
            if (shipPosition.X > MaxX)

            {

                shipPosition.X = MaxX;

            }

            else if (shipPosition.X < MinX)

            {

                shipPosition.X = MinX;

            }

            else if (shipPosition.Y > MaxY)

            {

                shipPosition.Y = MaxY;

            }

            else if (shipPosition.Y < MinY)

            {

                shipPosition.Y = MinY;

            }

        }

I call this method in Update()

ccoonen · #2 (**permalink**) 09-17-2007, 07:00 AM

I'm not familiar with XNA but sounds like I should get into it - is XNA like the .NET 3.0 Xaml thing?

Lee · #3 (**permalink**) 09-17-2007, 08:29 AM

I always had it down as the easier and less powerful thing too something like DirectX

HelloWorld · #4 (**permalink**) 09-17-2007, 11:41 AM

XNA is built upon DirectX, I think it's really powerful to just make an INDIE game, and since I don't know what are things that you can't do in XNA that you can do if you just use DirectX, well the difference probably you're more using C++ and know what craps behind everything, but XNA is a way for you to focus more with the game play and the fun of it, not the craps. Moreover, I'm now waiting for XNA 2.0 where they supports networking, etc etc... Here's the link:

XNA Team Blog : Announcing XNA Game Studio 2.0

ccoonen · #5 (**permalink**) 09-17-2007, 01:41 PM

Great... Now I got the bug!, lol (Downloading XNA Game STudio Express 1.0 Refresh right now)...

HelloWorld · #6 (**permalink**) 09-17-2007, 02:30 PM

I found the solution for this one

Quote:

Oh, I see your problem.

Your ships are in 3D coordinates, which are completely different from the screen coordinates. So your Max/Min X/Z values should be computed in spatial coordinates. These values, after you find them will be resolution independent.

They are tied to the camera view and projection matrices. The distance from the XZ, and the field of view both determine how much of that plane you can see, and what are the bounds that you're looking for. If the distance is larger, or the field of view is greater, more area will be visible. If the distace is lower, or the field of view is narrower, less area will be visible. But since your distance is fixed (8000) and fov is also fixed (45), once you find appropriate values (begin with +-500 for both axis, and slowly increase until you reach a value you are satisfied with), you can hardcode them.

I don't know how to better explain this more clearly...

PHP Code:

  public void CheckBoundaryCollision()
        {
            int MaxX = 500;
            int MinX = -500;

            int MaxZ = 500;
            int MinZ = -500;

            if (shipPosition.X > MaxX)
            {
                shipPosition.X = MaxX;
            }
            else if (shipPosition.X < MinX)
            {
                shipPosition.X = MinX;
            }
            
            if (shipPosition.Z > MaxZ)
            {
                shipPosition.Z = MaxZ;
            }
            else if (shipPosition.Z < MinZ)
            {
                shipPosition.Z = MinZ;
            }
        }

Quote:

Then run the game, and see how the ships behave. After that, modify the MaxX, MinX, MaxZ and MinZ values slightly (add / subtract 100), run again, and repeat this process until the boundaries are ok.

You don't have to do anything with Viewport.Width and Viewport.Height. The coordinates in space have no relation to these values.

Thanx for XBOX Live ID CatalinZima for the answer

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