Collision problems - GameCreators Forum

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Alvind

16

Years of Service

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Joined: 6th Dec 2007

Location: Northern Ireland

Posted: 14th Nov 2013 21:35

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Hi guys I'm having a bit of a problem learning my way around DarkBasic Pro.

Displayed is the program which I'm creating, the exact problem I have is whenever the player (a tank) comes close to a mesh I created (to act as a wall) it starts to sink below the level of the mesh and goes under it rather than just stopping dead.
It then stays on the level it sunk down to.

Where should I start looking?

REM *** STREETPLATFORMER LEARNING TUTORIAL ***
REM *** MAIN OBJECTIVE: TO CREATE A 3D PLATFORM STYLE GAME WITH A INTERACTIVE CHARACTER THAT SHOOTS OTHER NON PLAYABLE CHARACTERS ON ONE LEVEL ONLY ***
REM *** 19/10/2013 ALVIN DEWART ***

REM *** DISPLAY MODES ***
SET DISPLAY MODE 1024,768,32
SYNC ON
SYNC RATE 50
HIDE MOUSE
SET CAMERA RANGE 0,100,7500

REM *** LEVEL ***
MAKE OBJECT PLAIN 1,1500,1500
POSITION OBJECT 1,0,0,0
XROTATE OBJECT 1,-90
LOAD IMAGE "OldFloor.bmp",2
TEXTURE OBJECT 1,2
SCALE OBJECT TEXTURE 1,16,16

REM *** SKYSPHERE ***
MAKE OBJECT SPHERE 6,10000
SET OBJECT CULL 6,0
SET OBJECT WIREFRAME 6,0
LOAD IMAGE "SkyBox.bmp",7
TEXTURE OBJECT 6,7
SCALE OBJECT TEXTURE 6,12,12

REM *** PLAYER ***
LOAD OBJECT "Tank.X",2
COLOR OBJECT 2,RGB(0,128,0)
SCALE OBJECT 2,50,50,50
POSITION OBJECT 2,0,25,-500
SET OBJECT COLLISION ON 2
SHOW OBJECT BOUNDS 2,1
XPos#=0: YPos#=0: ZPos#=0

REM YELLOW ENEMY TANK
LOAD OBJECT "Tank.x",3
COLOR OBJECT 3,RGB(128,128,0)
SCALE OBJECT 3,50,50,50
POSITION OBJECT 3,0,25,500
YROTATE OBJECT 3,180
SET OBJECT COLLISION ON 3
SHOW OBJECT BOUNDS 3,1

REM *** WALL COLLISION TEST ***
LOAD OBJECT "Wall.x",4
LOAD IMAGE "CollisionWall.jpg",1
SCALE OBJECT 4,3000,125,500
TEXTURE OBJECT 4,1
SCALE OBJECT TEXTURE 4,1,12
POSITION OBJECT 4,-750,-25,-300
XROTATE OBJECT 4,-90
YROTATE OBJECT 4,90
SET OBJECT COLLISION ON 4
SHOW OBJECT BOUNDS 4,1

DO

REM *** CAMERA CONTROLS ***
  If Upkey()=1 Then Move Object 2,5
  If Downkey()=1 Then Move Object 2,-5
  If Leftkey()=1 Then TURN OBJECT LEFT 2,5
  If Rightkey()=1 Then TURN OBJECT RIGHT 2,5
  YROTATE OBJECT 6, OBJECT ANGLE Y(6) + 0.025

REM *** CAMERA FOLLOWING MOVEMENT ***
    XPos#=Object Position X(2)
    YPos#=Object Position Y(2)
    ZPos#=Object Position Z(2)

Rem The collision bit
  IF OBJECT COLLISION(2,4) > 0
    Dec XPos#,Get Object Collision X()
    Dec YPos#,Get Object Collision Y()
    Dec ZPos#,Get Object Collision Z()
  ENDIF
POSITION OBJECT 2,XPos#,YPos#,ZPos#

IF OBJECT COLLISION(2,3) > 0
    Dec XPos#,Get Object Collision X()
    Dec YPos#,Get Object Collision Y()
    Dec ZPos#,Get Object Collision Z()
  endif
Position Object 2,XPos#,YPos#,ZPos#

REM  CAMERA TO FOLLOW PLAYER
SET CAMERA TO FOLLOW XPos#, YPos#, ZPos#, 45 , 300, 150, 25, 0

SYNC
LOOP

WAIT KEY
END

+ Code Snippet

REM *** STREETPLATFORMER LEARNING TUTORIAL ***
REM *** MAIN OBJECTIVE: TO CREATE A 3D PLATFORM STYLE GAME WITH A INTERACTIVE CHARACTER THAT SHOOTS OTHER NON PLAYABLE CHARACTERS ON ONE LEVEL ONLY ***
REM *** 19/10/2013 ALVIN DEWART ***


REM *** DISPLAY MODES ***
SET DISPLAY MODE 1024,768,32
SYNC ON
SYNC RATE 50
HIDE MOUSE
SET CAMERA RANGE 0,100,7500


REM *** LEVEL ***
MAKE OBJECT PLAIN 1,1500,1500
POSITION OBJECT 1,0,0,0
XROTATE OBJECT 1,-90
LOAD IMAGE "OldFloor.bmp",2
TEXTURE OBJECT 1,2
SCALE OBJECT TEXTURE 1,16,16


REM *** SKYSPHERE ***
MAKE OBJECT SPHERE 6,10000
SET OBJECT CULL 6,0
SET OBJECT WIREFRAME 6,0
LOAD IMAGE "SkyBox.bmp",7
TEXTURE OBJECT 6,7
SCALE OBJECT TEXTURE 6,12,12



REM *** PLAYER ***
LOAD OBJECT "Tank.X",2
COLOR OBJECT 2,RGB(0,128,0)
SCALE OBJECT 2,50,50,50
POSITION OBJECT 2,0,25,-500
SET OBJECT COLLISION ON 2
SHOW OBJECT BOUNDS 2,1
XPos#=0: YPos#=0: ZPos#=0

REM YELLOW ENEMY TANK
LOAD OBJECT "Tank.x",3
COLOR OBJECT 3,RGB(128,128,0)
SCALE OBJECT 3,50,50,50
POSITION OBJECT 3,0,25,500
YROTATE OBJECT 3,180
SET OBJECT COLLISION ON 3
SHOW OBJECT BOUNDS 3,1


REM *** WALL COLLISION TEST ***
LOAD OBJECT "Wall.x",4
LOAD IMAGE "CollisionWall.jpg",1
SCALE OBJECT 4,3000,125,500
TEXTURE OBJECT 4,1
SCALE OBJECT TEXTURE 4,1,12
POSITION OBJECT 4,-750,-25,-300
XROTATE OBJECT 4,-90
YROTATE OBJECT 4,90
SET OBJECT COLLISION ON 4
SHOW OBJECT BOUNDS 4,1



DO

   REM *** CAMERA CONTROLS ***
  If Upkey()=1 Then Move Object 2,5
  If Downkey()=1 Then Move Object 2,-5
  If Leftkey()=1 Then TURN OBJECT LEFT 2,5
  If Rightkey()=1 Then TURN OBJECT RIGHT 2,5
  YROTATE OBJECT 6, OBJECT ANGLE Y(6) + 0.025

 REM *** CAMERA FOLLOWING MOVEMENT ***
    XPos#=Object Position X(2)
    YPos#=Object Position Y(2)
    ZPos#=Object Position Z(2)

  Rem The collision bit
  IF OBJECT COLLISION(2,4) > 0
    Dec XPos#,Get Object Collision X()
    Dec YPos#,Get Object Collision Y()
    Dec ZPos#,Get Object Collision Z()
  ENDIF
POSITION OBJECT 2,XPos#,YPos#,ZPos#

 IF OBJECT COLLISION(2,3) > 0
    Dec XPos#,Get Object Collision X()
    Dec YPos#,Get Object Collision Y()
    Dec ZPos#,Get Object Collision Z()
  endif
Position Object 2,XPos#,YPos#,ZPos#


REM  CAMERA TO FOLLOW PLAYER
SET CAMERA TO FOLLOW XPos#, YPos#, ZPos#, 45 , 300, 150, 25, 0

   SYNC
LOOP


WAIT KEY
END

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29 games

19

Years of Service

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Joined: 23rd Nov 2005

Location: not entirely sure

Posted: 14th Nov 2013 23:04

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Without your models I can't prove it but when the tank collides with the wall the "Get Object Collision Y()" is returning a small negative value. Try writing the result of the "Get Object Collision Y()" and printing it to the screen to see what's going on.

The easiest thing would be to just remove "Dec YPos#,Get Object Collision Y()" from both bits of collision code. If the movement of the tanks is purely on the XZ plane then you don't need to resolve the collision on the Y axis anyway.

This may sound like an overly simplistic solution but it's the sort of thing I do.

one of these days I'll come up with a better signature

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Derek Darkly

13

Years of Service

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Joined: 22nd Sep 2011

Location: Whats Our Vector, Victor?

Posted: 15th Nov 2013 15:55

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Correct me if I'm wrong, but since your floor is a flat plain your Y position should never really change, so just find out what that position is and keep using it:

Position Object 2,XPos#,n#,ZPos#

D.D.

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LBFN

17

Years of Service

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Joined: 7th Apr 2007

Location: USA

Posted: 15th Nov 2013 16:08 Edited at: 15th Nov 2013 16:09

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Totally agree with what has been suggested so far. I made up some dummy objects and ran the program and did not see the issue you are seeing. As a suggestion, you might consider adjusting the Y height placement of your wall. Instead of hard-coding the Y placement, maybe check to see the object's height and divide it in half:

+ Code Snippet

original:   POSITION OBJECT 4,-750,-25,-300
suggested:  POSITION OBJECT 4,-750,object size y(4) * .5,-300

So many games to code.....so little time.

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Alvind

16

Years of Service

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Joined: 6th Dec 2007

Location: Northern Ireland

Posted: 16th Nov 2013 22:31

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Thanks guys I will give this a try. Many thanks!

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Alvind

16

Years of Service

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Joined: 6th Dec 2007

Location: Northern Ireland

Posted: 17th Nov 2013 20:15

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This did indeed work. Thanks

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