Matrices more and more

[AHMED3D]

Hi there, I am very new to Direct3D but I am willing to learn it and i like it despite im facing trouble in matrices (the whole thing) I just need help!!
I understand matrices as math and also i got the coordinates thing in Direct3D but i cant find a resource where i can learn how to use matrices in Direct3D programming.
I want to make simple (i think) thing which is:

I load a gamefield mesh then i load a number of boxes then i want to move these boxes and (also) i want to move the camera throughout the game field.

I learnt how to load meshes but i need to put them in specefic places on the gamefield, so i know that i must assign a matrix to each object Right?? then how?? can anybody explain??

Also when i try to make the camera move i get: strafe right and left and move ahead and back but how can i rotate it and not mess with the coordinates??

thanks in advance

 

[Darc]

ok, heres the camera part, took me a while to understand it myself so if you have questions feel free to ask. I have this in its own Class (Camera) and I havent made it look up and down yet:

    Public xPos, yPos, zPos, xView, yView, zView, xUp, yUp, zUp, xStrafe, yStrafe, zStrafe As Single

    Public Sub New(ByVal x As Single, ByVal y As Single, ByVal z As Single, _
                    ByVal xV As Single, ByVal yV As Single, ByVal zV As Single, _
                    ByVal xU As Single, ByVal yU As Single, ByVal zU As Single)
        xPos = x
        yPos = y
        zPos = z
        xView = xV
        yView = yV
        zView = zV
        xUp = xU
        yUp = yU
        zUp = zU
    End Sub

    Private Sub UpdateCamera(ByVal xdir As Single, ByVal zdir As Single, ByVal dir As Single)
        xPos += xdir * dir
        zPos += zdir * dir

        xView += xdir * dir
        zView += zdir * dir
    End Sub

    Public Sub MoveCamera(ByVal amount As Single) Amount will be Negative for moving backwards
        Dim xLookDirection, yLookDirection, zLookDirection As Single

        xLookDirection = xView - xPos
        yLookDirection = yView - yPos
        zLookDirection = zView - zPos

        Dim dp As Single = CSng(Math.Sqrt(xLookDirection * xLookDirection + yLookDirection * yLookDirection + zLookDirection * zLookDirection))
        xLookDirection /= dp
        yLookDirection /= dp
        zLookDirection /= dp

        UpdateCamera(xLookDirection, zLookDirection, amount)
    End Sub

    Public Sub StrafeCamera(ByVal direction As Single) Negative = Left, Positive = Right
        CalculateStrafe()
        UpdateCamera(xStrafe, zStrafe, direction)
    End Sub

    Private Sub CalculateStrafe() 

        Dim xDir, yDir, zDir As Single
        Dim xCross, yCross, zCross As Single

        xDir = xView - xPos
        yDir = yView - yPos
        zDir = zView - zPos

        Dim dp As Single = 1 / CSng(Math.Sqrt(xDir * xDir + yDir * yDir + zDir * zDir))
        xDir *= dp
        yDir *= dp
        zDir *= dp

        xCross = (yDir * zUp) - (zDir * yUp)
        yCross = (zDir * xUp) - (xDir * zUp)
        zCross = (xDir * yUp) - (yDir * xUp)

        xStrafe = xCross
        yStrafe = yCross
        zStrafe = zCross
    End Sub

    Public Sub RotateCamera(ByVal AngleDir As Single, ByVal xSpeed As Single, ByVal ySpeed As Single, ByVal zSpeed As Single) AngleDir will be Negative for rotating left, positive for right
        Dim xNewLookDirection, yNewLookDirection, zNewLookDirection As Single
        Dim xLookDirection, yLookDirection, zLookDirection As Single
        Dim CosineAngle, SineAngle As Single

        CosineAngle = CSng(Math.Cos(AngleDir))
        SineAngle = CSng(Math.Sin(AngleDir))

        xLookDirection = xView - xPos
        yLookDirection = yView - yPos
        zLookDirection = zView - zPos

        Dim l As Single = CSng(Math.Sqrt(xLookDirection * xLookDirection + yLookDirection * yLookDirection + zLookDirection * zLookDirection))
        xLookDirection /= l
        yLookDirection /= l
        zLookDirection /= l

        xNewLookDirection = (CosineAngle + (1 - CosineAngle) * xSpeed) * xLookDirection
        xNewLookDirection += ((1 - CosineAngle) * xSpeed * ySpeed - zSpeed * SineAngle) * yLookDirection
        xNewLookDirection += ((1 - CosineAngle) * xSpeed * zSpeed + ySpeed * SineAngle) * zLookDirection

        yNewLookDirection = ((1 - CosineAngle) * xSpeed * ySpeed + zSpeed * SineAngle) * xLookDirection
        yNewLookDirection += (CosineAngle + (1 - CosineAngle) * ySpeed) * yLookDirection
        yNewLookDirection += ((1 - CosineAngle) * ySpeed * zSpeed - xSpeed * SineAngle) * zLookDirection

        zNewLookDirection = ((1 - CosineAngle) * xSpeed * zSpeed - ySpeed * SineAngle) * xLookDirection
        zNewLookDirection += ((1 - CosineAngle) * ySpeed * zSpeed + xSpeed * SineAngle) * yLookDirection
        zNewLookDirection += (CosineAngle + (1 - CosineAngle) * zSpeed) * zLookDirection


        xView = xPos + xNewLookDirection
        yView = yPos + yNewLookDirection
        zView = zPos + zNewLookDirection
    End Sub

 

[AHMED3D]

I really appreciate your help but i just still dont get it. First I program in c# but i managed to convert your code (thanx) but that was not the thing i need. What i needed is to learn how to use matrices in Direct3D and make things and cameras move. Although i need it to be simple with explanation (Im still new you know). Another thing is that I saw your Camera calss but i dont know how to use it with the view matrix (i think). So I need help

 

[Darc]

oh ok. Thats the easy part (if youre bad at that kinda math like me) well, for the camera part heres what I do (using the afore mentioned Camera class):

d3dDevice.Transform.View = Matrix.LookAtLH(New Vector3(View.xPos, View.yPos, View.zPos), _
                                                    New Vector3(View.xView, View.yView, View.zView), _
                                                    New Vector3(View.xUp, View.yUp, View.zUp))   set the view transformation
        d3dDevice.Transform.Projection = Matrix.PerspectiveFovLH(Convert.ToSingle(Math.PI) / 4, 1.0F, 1.0F, 100.0F) and finally set the projection matrix

Now explaining, Device.Transform is the group of matrices that are in the device, modify these, modify the world.
LookAtLH is simple take the camera position (the second argument) and point it at the camera view Vector (the second argument) The final argument is simply which way is up, in the form of a Vector.
Then we come to the Projection Matrix, like I said Im not good at this kind of math so I usually dont change the values from the above (if it works, it works right?) In laymens terms the first argument is field of vision (requires complicated math, I dont tinker with the above equation) the second I just dont understand lol, the third is the closest coordinate you can see and the final argument is the farthest coordinate you can see.

If you need more help, Im always willing

 

[AHMED3D]

Hi there. Thanx for your help. I think im beginning to get it. About the arguments in the projection matrix they are:
1st: Field (angle) of view (usually set to 90 degrees (pi/4) just to resemble the human eye) if you increase this angle you will see more of the view but also there will be more render and if you decrease this angle you will see less of the view.
2nd: Aspect ratio (Ratio of width over height of the field of view) this is usually set to 4/3 because the nature of the monitor is rectangle (not square) and this will make you see the square or cube as it is in reality
3rd: The most close distance your camera will view (i think that the closest is the better. I set it to 0.1)
4th: The mose far distance your camera will view (the less is the better for rendering optimization but not too less) We are usually not interested in viewing very far objects so this helps us not to draw them.

About me: Im doing well with matrices and now i can load a complete view and i think ill be able to move through it soon (thanx)

I have another question if you can help:
actually they are two:
1- How can i detect collision??
2- How can i draw shadows?? (I do lighting but there is no shadows)

 

[Darc]

Im still trying to figure out collisions myself, (damn crappy MS docs) as for shadows, Im not there yet