Movement Problems

[birvin]

Ok heres the problem i can get my ship to for foward back up down side to side with no problem.  My problem is when i point the ship in a particular heading i want it to go in that direction.  I have looked at many examples that came with truevision.  Heres my code.

    Public Sub ShipPosUpDate()
        'ShipPos.x = ShipPos.x + ShipSP * 0.01
        ShipPos.y = ShipPos.y + ShipThru * 0.01
        'ShipPos.z = ShipPos.z + ShipFP * 0.01
        ShipPos.x = ShipPos.x + System.Math.Cos(ShipHead) * ShipFP * 0.01
        ShipPos.z = ShipPos.z + System.Math.Sin(ShipHead) * ShipFP * 0.01
        ShipM.RotateY(ShipHead * 0.01, True)
        If ShipPos.y <> -34 And ShipPos.y > -34 Then
            ShipPos.y = ShipPos.y - 1 * 0.01
        ElseIf ShipPos.y = -34 Then
            ShipPos.y = -34
        End If

        ShipM.SetPosition(ShipPos.x, ShipPos.y, ShipPos.z)
    End Sub

when i rotate the ship it kinda does go in that direction but if i hold down the keys that change the angle of the ship it is all jerky and stops goin in the right direction. 

[newborn]

simply use meshShip.MoveRelative, its gonna save you tons of time and headaches.

[birvin]

ok ill try it

[birvin]

well when i use that the ships mesh is no longer there

[nateslunaXX]

why don't you use newton physics to move your ship..just addimpulse towards the direction vector...which you don't have to calculate. there is this .getBasisVectors method..

[birvin]

i realy wana figure out why this aint working ive copied the bit of code that i thought was what made the particular thing move in the direction it is oriented.  is there some forumala that people use to get the amount of movement in the x,z cords based on a particular angle cause im a bit rusty on my algebra and geomety.  im gonna go in search for a book that has the mathmatics for game programming anf maybe even physics.

[ovek]

birvin this will make you go forward or backward based on your heading/direction/angle whatever you want to call it:

Code:

If TVInputEngine.IsKeyPressed(MTV3D65.CONST_TV_KEY.TV_KEY_UPARROW) Then
MyActorPosition.x = MyActorPosition.x - TVEngine.TimeElapsed * Math.Sin(MyActorAngle) * 0.03
MyActorPosition.z = MyActorPosition.z - TVEngine.TimeElapsed * Math.Cos(MyActorAngle) * 0.03
End If
If TVInputEngine.IsKeyPressed(MTV3D65.CONST_TV_KEY.TV_KEY_DOWNARROW) Then
MyActorPosition.x = MyActorPosition.x + TVEngine.TimeElapsed * Math.Sin(MyActorAngle) * 0.03
MyActorPosition.z = MyActorPosition.z + TVEngine.TimeElapsed * Math.Cos(MyActorAngle) * 0.03
End If

and use myactorangle to base your angle like so:

Code:

If TVInputEngine.IsKeyPressed(MTV3D65.CONST_TV_KEY.TV_KEY_LEFTARROW) Then
MyActorAngle = MyActorAngle - TVEngine.TimeElapsed * 0.003
End If
If TVInputEngine.IsKeyPressed(MTV3D65.CONST_TV_KEY.TV_KEY_RIGHTARROW) Then
MyActorAngle = MyActorAngle + TVEngine.TimeElapsed * 0.003
End If

[birvin]

thanks i figured it had some cos sin stuff in it ill try it later

[birvin]

what is the 0.03 at the end is that the number for the speed?

[ovek]

yea

[birvin]

thanks dude

[Arakiel]

Slight thread resurrection here but I registered for the forums simply to post a thank you to newborn for this simple, yet oh so helpful 1 liner.

simply use meshShip.MoveRelative, its gonna save you tons of time and headaches.

I had spent 3 hours trying to work out some similar movement code and failing (my math-fu is weak) and looked all over the place trying to find a sample of something similar before I finally stumbled upon this thread...and replaced 14 lines of non-working crud with 1 oh so beautiful line.  You've just made my night...granted you posted it 8 months ago but here is at least one belated thank you!

-Arakiel

[newborn]

Welcome to the boards!

I'm glad it helped at least 1 person!

Feel free to ask (intelligent questions) and we shall answer (if we know the answer). 

[jviper]

Code:

Public Sub ShipPosUpDate()
        'ShipPos.x = ShipPos.x + ShipSP * 0.01
        ShipPos.y = ShipPos.y + ShipThru * 0.01
        'ShipPos.z = ShipPos.z + ShipFP * 0.01
        ShipPos.x = ShipPos.x + System.Math.Cos(ShipHead) * ShipFP * 0.01
        ShipPos.z = ShipPos.z + System.Math.Sin(ShipHead) * ShipFP * 0.01
        ShipM.RotateY(ShipHead * 0.01, True)
        If ShipPos.y <> -34 And ShipPos.y > -34 Then
            ShipPos.y = ShipPos.y - 1 * 0.01
        ElseIf ShipPos.y = -34 Then
            ShipPos.y = -34
        End If

        ShipM.SetPosition(ShipPos.x, ShipPos.y, ShipPos.z)
    End Sub

Sorry to be flagrant here, but this code is not right. The correct code should be:

Code:

ShipPos = ShipPos + (Speed*0.01)*ShipM.GetDirection()

This will always move your mesh in the ship's direction. This is actually what the MoveRelative function does. But the MoveRelative function will cause a blow up (mesh disapears or acts completly wild) if your mesh's direction is (0,0,0). It will also blow up if any of your scale components are 0, that is (scale.x = 0 or scale.y = 0 or scale.z = 0). The above code will simply will not move if any of that is true.

...and it seems alot of ppl seem to think alot of things require trignometric functions. It this case it could, but it does not have to. And if you do use them, you have to consider how to use them. I may have to post a new thread about it if it becomes an epidemic.