Gravity

[kcraft]

I posted in the Features request list about adding a function for Gravity. I attempted what was sent to me in a reply, but the results are semi-good?

Heres the code (more below the code):

Code: Select all

;
; ------------------------------------------------------------
;
;   PureBasic - SkyDome
;
;    (c) 2003 - Fantaisie Software
;
; ------------------------------------------------------------
;

#CameraSpeed = 25

IncludeFile "Screen3DRequester.pb"

DefType.f KeyX, KeyY, MouseX, MouseY

If InitEngine3D()

  Add3DArchive("Data\"          , #PB_3DArchive_FileSystem)
  Add3DArchive("Data\Skybox.zip", #PB_3DArchive_Zip)
  
  InitSprite()
  InitKeyboard()
  InitMouse()
  
  If Screen3DRequester()
    
    AmbientColor(RGB(255,255,255))
    
    CreateMaterial(0, LoadTexture(2, "r2skin.jpg"))
    CreateEntity  (0, LoadMesh(2, "Robot.mesh"), MaterialID(0), -1, -2, -3)
    CreateMaterial  (0, LoadTexture(0, "Terrain_Texture.jpg"))
    AddMaterialLayer(0, LoadTexture(1, "Terrain_Detail.jpg"), 1)

    CreateTerrain("Terrain.png", MaterialID(0), 40, 1, 40, 0)

    SkyDome("Clouds.jpg", 30)

    CreateCamera(0,0,0,100,100)
    CameraLocate(0,3700,20,1775)

    Repeat
      Screen3DEvents()
      Ground = TerrainHeight(oldx,oldz)      
      If ExamineKeyboard()
        
        If KeyboardPushed(#PB_Key_Left)
          KeyX = CameraX(0) - #CameraSpeed ;- I changed all of these to say CameraX(0)
        ElseIf KeyboardPushed(#PB_Key_Right)
          KeyX = CameraX(0) + #CameraSpeed 
        Else
          KeyX = CameraX(0)
        EndIf
                  
        If KeyboardPushed(#PB_Key_Up)
          KeyY = CameraZ(0) - #CameraSpeed 
        ElseIf KeyboardPushed(#PB_Key_Down)
          KeyY = CameraZ(0) + #CameraSpeed 
        Else
          KeyY = CameraZ(0)
        EndIf

      EndIf
      
      If ExamineMouse()
        MouseX = -(MouseDeltaX()/10)*#CameraSpeed/2
        MouseY = -(MouseDeltaY()/10)*#CameraSpeed/2
      EndIf
     
     
      oldx = CameraX(0)
      oldy = ground + 20
      oldz = CameraZ(0)
      ;- This is where I changed it to attempt a gravity effect -------------------
      CameraLocate(0, KeyX, oldy, KeyY)
      RotateCamera(0, MouseX, MouseY, RollZ)
      ;MoveCamera  (0, KeyX, 0, KeyY)
      
      
      ; Get Terrain Height -----------------------------------------------------------
      
      RenderWorld()
      Screen3DStats()      
      FlipBuffers()
    Until KeyboardPushed(#PB_Key_Escape) Or Quit = 1
  EndIf
    
Else
  MessageRequester("Error", "The 3D Engine can't be initialized",0)
EndIf
  

All of the files it calls for are in the Examples/Data folder.

What happens here is:

1. The camera stays at 20 above the terrain height.
2. The camera can look around.
3. When you move, using the up arrow key, it only goes 1 direction.
same with all the other keys. The movement does not match what
way the camera is looking.

If anyone could throw some hints as to what I can do to get this working, it would be much appreciated.

Is there a function for determining where the camera is pointing? If so, how could I get the movement to change to that direction?

thanks

[LarsG]

If nobody replies to this, I'll take a look at it when I get home..

-Lars

[LarsG]

Okay, I had I little look at it...
And the first thing that happened when I comiled it, was that it crashed.. hehe (so I fixed that)..

Then after a bit tweaking and reorganizing of the code, I came up with this....
It's probably not the best way to do it, but it works..

[edit] note that I also kept the media in the "data" directory [/edit]

Code: Select all

;
;
; Keeping constant distance to terrain example
; by Lars Gretnes, 2003
;

#CameraSpeed  = 20
#WalkSpeed    = 50

IncludeFile "Screen3DRequester.pb" 

DefType.f KeyX, KeyY, MouseX, MouseY 

If InitEngine3D() 

  Add3DArchive("Data\"          , #PB_3DArchive_FileSystem) 
  Add3DArchive("Data\Skybox.zip", #PB_3DArchive_Zip) 
  
  InitSprite() 
  InitKeyboard() 
  InitMouse() 
  
  If Screen3DRequester() 

    AmbientColor(RGB(255,255,255))

    ; load the mesh (robot)
    LoadMesh(0, "data\Robot.mesh")
    LoadTexture(2, "data\r2skin.jpg")
    CreateMaterial (0, TextureID(2))
    CreateEntity (0, MeshID(0), MaterialID(0), -1, -2, -3)
    
    ; load terrain
    LoadTexture (0, "data\Terrain_Texture.jpg")
    LoadTexture (1, "data\Terrain_Detail.jpg")
    CreateMaterial (1, TextureID(0))
    AddMaterialLayer(0, TextureID(1), 1) 
    CreateTerrain("data\Terrain.png", MaterialID(1), 40, 1, 40, 0) 

    SkyDome("data\Clouds.jpg", 30) 

    ; create and place the camera
    CreateCamera(0,0,0,100,100) 
    CameraLocate(0,3700,50,1775) 

    Repeat 
      Screen3DEvents() 
 
       ; get the key input
       If ExamineKeyboard() 
        If KeyboardPushed(#PB_Key_Left) 
          KeyX = -#WalkSpeed 
        ElseIf KeyboardPushed(#PB_Key_Right) 
          KeyX = #WalkSpeed 
        Else 
          KeyX = 0 
        EndIf 
                  
        If KeyboardPushed(#PB_Key_Up) 
          KeyY = -#WalkSpeed 
        ElseIf KeyboardPushed(#PB_Key_Down) 
          KeyY = #WalkSpeed 
        Else 
          KeyY = 0 
        EndIf

      EndIf
      
      ; get mousemovement
      If ExamineMouse() 
        MouseX = -(MouseDeltaX()/10)*#CameraSpeed/2 
        MouseY = -(MouseDeltaY()/10)*#CameraSpeed/2 
      EndIf 
      
      ; get the terrain heigh at the player coords
      ypos = TerrainHeight(CameraX(0) ,CameraZ(0)) + 50

      ; move the camera, and keep the height at +50
      RotateCamera (0, MouseX, MouseY, 0) 
      MoveCamera (0, KeyX, 0, KeyY)
      CameraLocate (0, CameraX(0), ypos, CameraZ(0))
 
      ; render world
      RenderWorld() 
      FlipBuffers() 

    Until KeyboardPushed(#PB_Key_Escape)
  EndIf 
    
Else 
  MessageRequester("Error", "The 3D Engine can't be initialized",0) 
EndIf 

[kcraft]

That helps. Now I understand how it works. Thanks Alot.

lol. Now we have to figure out jumping, and we're set!

[LarsG]

jumping , eh?!?
well.. it's not exactly optimized.. nor is it any good, but it may be something for you to work on?!?!

Code: Select all

;
;
; Keeping constant distance to terrain example
; by Lars Gretnes, 2003
;

#CameraSpeed  = 20
#WalkSpeed    = 50

jumping.b = 0
jumpvar.b = 0

IncludeFile "Screen3DRequester.pb" 

DefType.f KeyX, KeyY, MouseX, MouseY 

If InitEngine3D() 

  Add3DArchive("Data\"          , #PB_3DArchive_FileSystem) 
  Add3DArchive("Data\Skybox.zip", #PB_3DArchive_Zip) 
  
  InitSprite() 
  InitKeyboard() 
  InitMouse() 
  
  If Screen3DRequester() 

    AmbientColor(RGB(255,255,255))

    ; load the mesh (robot)
    LoadMesh(0, "data\Robot.mesh")
    LoadTexture(2, "data\r2skin.jpg")
    CreateMaterial (0, TextureID(2))
    CreateEntity (0, MeshID(0), MaterialID(0), -1, -2, -3)
    
    ; load terrain
    LoadTexture (0, "data\Terrain_Texture.jpg")
    LoadTexture (1, "data\Terrain_Detail.jpg")
    CreateMaterial (1, TextureID(0))
    AddMaterialLayer(0, TextureID(1), 1) 
    CreateTerrain("data\Terrain.png", MaterialID(1), 40, 1, 40, 0) 

    SkyDome("data\Clouds.jpg", 30) 

    ; create and place the camera
    CreateCamera(0,0,0,100,100) 
    CameraLocate(0,3700,50,1775) 

    Repeat 
      Screen3DEvents() 
 
      ; get the key input
      If ExamineKeyboard() 
        If KeyboardPushed(#PB_Key_Left) 
          KeyX = -#WalkSpeed 
        ElseIf KeyboardPushed(#PB_Key_Right) 
          KeyX = #WalkSpeed 
        Else 
          KeyX = 0 
        EndIf 
                  
        If KeyboardPushed(#PB_Key_Up) 
          KeyY = -#WalkSpeed 
        ElseIf KeyboardPushed(#PB_Key_Down) 
          KeyY = #WalkSpeed 
        Else 
          KeyY = 0 
        EndIf

        If KeyboardPushed(#PB_Key_Space)
          jumping = 1
        EndIf
      EndIf
      
      ; get mousemovement
      If ExamineMouse() 
        MouseX = -(MouseDeltaX()/10)*#CameraSpeed/2 
        MouseY = -(MouseDeltaY()/10)*#CameraSpeed/2 
      EndIf 
      
      If jumping > 0
        ; were jumping
        ; check if wer're going up or down
        If jumping = 1
          ; were going UP
          jumpvar +3
          If jumpvar => 60
            jumping = 2
          EndIf
        ElseIf jumping = 2
          jumpvar -3
          If jumpvar <= 0
            jumping = 0
          EndIf
        EndIf
      EndIf
      
      ; set the terrain heigh at the player coords
      ypos = TerrainHeight(CameraX(0) ,CameraZ(0)) + 50 + jumpvar
      ; move the camera, and keep the height at +50
      RotateCamera (0, MouseX, MouseY, 0) 
      MoveCamera (0, KeyX, 0, KeyY)
      CameraLocate (0, CameraX(0), ypos, CameraZ(0))
 
      ; render world
      RenderWorld() 
      FlipBuffers() 

    Until KeyboardPushed(#PB_Key_Escape)
  EndIf 
    
Else 
  MessageRequester("Error", "The 3D Engine can't be initialized",0) 
EndIf 

[LarsG]

You might want to read up on the use of Sinus and Cosine to calculate the jump and gravity, as this is more correct, and gives you a much smoother transition when jumping... I've never calculated this is three dimensions, so I might have to read up on that as well... hehe

-Lars

[kcraft]

Thanks again! That really helps, I tweaked it a bit by putting a check in at the jump key

basically if ImJumping = 1 ignore the space bar.

[kcraft]

in reply to sin/cos

I kinda figured that I would. I was playing around with it earlier, made the mountains much taller, then tried to jump off of them and I basically hopped down the side, one step at a time. It was rather funny. I have another game that I am baseing my movement off of, and when I jump it looks as if it determines whether I am moving forward/backward or not, and adjusts my height accordingly. When I take that system and jump from the top of a mountain, I fall to my death. Which is basically what I am looking for on my game, just gonna take time to figure out all the maths and such.

thanks again.

[LarsG]

Jumping up and down a mountain (or similar), will actually not be any problem when you get the physics up and running..
Basically, what you want to do, is to have a constant, #gravity, that pulls down the player constantly in the Y-axis (the correct value for Earth is 9.8, but you'd rather adjust it to suit your needs)...
Then, when the player makes a jump, you'd actually give him a push upward the Y-axis, and calculate the vector of the player when he's "in the air".. this is (normally) done by something like:
(note: I'm not sure if this specific formula would work cause I haven't tried it..)

Code: Select all

y_vector = sin(player_angle) * push_speed

then you add this vector to the player position and subtract the gravity as well.. (and subtract values for friction etc. if you want)

I guess I really have to test some of this later, but I think you get the general idea...
Good luck..

-Lars