Tweening/Flick Problem

Blitz3D Forums/Blitz3D Beginners Area/Tweening/Flick Problem

blackbag

(Posted 2008) [#1]

After reading a recent posting on tweening to get a constant game speed I have given it a go, but I am little stuck now.

Tweening works but has an unanticipated effect. In my game if an object gets too far away from the player it get wrapped around to the other side of the player. I use positionentity followed by resetentity to acheive this. And it was all working fine till I implemented the tweening code.

You now get glimpses of the objects as they flick past, I kinda understand why this happens but I am a loss on how to stop it. I have tried hiding the entity before the position and showing it after, but this makes not difference (and i kinda understand why this happens too).

Any ideas?

The offending code looks like this at the moment (just the move bit)

For stuff.blitz_obj = Each blitz_obj

	If Abs(EntityX (stuff\mesh)-EntityX(player_mesh)) > bound Then
		HideEntity(stuff\mesh)
		If EntityX (stuff\mesh) < EntityX(player_mesh) Then
			PositionEntity (stuff\mesh,EntityX(stuff\mesh)+(bound*2),EntityY(stuff\mesh),0)
		Else
			PositionEntity (stuff\mesh,EntityX(stuff\mesh)-(bound*2),EntityY(stuff\mesh),0)
		EndIf
		ShowEntity(stuff\mesh)
		ResetEntity stuff\mesh
	EndIf
	If Abs(EntityY (stuff\mesh)-EntityY(player_mesh)) > bound Then
		HideEntity (stuff\mesh)
		If EntityY (stuff\mesh) < EntityY(player_mesh) Then
			PositionEntity (stuff\mesh,EntityX,EntityY(stuff\mesh)+(bound*2),0)
		Else
			PositionEntity (stuff\mesh,EntityX,EntityY(stuff\mesh)-(bound*2),0)

		EndIf	
		ShowEntity (stuff\mesh)
		ResetEntity stuff\mesh
	EndIf
	TranslateEntity (stuff\mesh,stuff\xv,stuff\yv,0)
	
Next

Zethrax

(Posted 2008) [#2]

Try doing any repositioning over a large distance, immediately before the CaptureWorld command. If necessary (and practical), cache the data instructing the program to 'teleport' the object, into a typelist, and process the list before CaptureWorld.

Here's some test code I made up using a modified version of the castle demo. It just shows a cube with a collision sphere being moved between two positions. The cube's collision sphere is set up to collide with the player, and visa-versa, so you can walk the player character between the two cube positions to check that no unwanted collision is occuring during the teleport. As you can see, there are no ghost images between the two cube positions, as the cube is being moved immediately before the CaptureWorld command is executed.

To run this code, you'll need to create a .bb file in the castle demo folder ( C:\Program Files\Blitz3D\Samples\Blitz 3D Samples\mak\castle ) and place the code in that file.

To see the code I've modified for the test, look for code between lines marked with ';******'.



; Search for 'Code added' to find the added code.


; -- Code added.
Const C_RESTITUTION_INCREMENT# = 0.02
Global G_restitution# = 0.1
Global G_smart_cam_flag
Global G_smart_cam_restitution# = 1.0
Const C_SMART_CAM_RESTITUTION_INCREMENT# = 0.02
Global G_millisecs
;^^^^^^


Include "C:\Program Files\Blitz3D\codelibs\CONSTANTS\keyconstants.bb"

Const FPS = 30
Const n_trees=100

Graphics3D 800, 600, 0, 1
SetBuffer BackBuffer()
HidePointer

Global shoot=Load3DSound( "sounds\shoot.wav" )
Global boom=Load3DSound( "sounds\boom.wav" )
SoundVolume boom,.5

Type Player
	Field entity,model
	Field anim_speed#,player_y#,roll#
End Type

Type ChaseCam
	Field entity,camera,target,heading,sky
End Type

Type Spark
	Field alpha#,sprite
End Type
	
Type Bullet
	Field rot#,sprite,time_out
End Type

Type Hole
	Field alpha#,sprite
End Type

Const TYPE_PLAYER=1,TYPE_BULLET=2,TYPE_TARGET=3

Const TYPE_SCENERY=10,TYPE_TERRAIN=11

Collisions TYPE_PLAYER,TYPE_TERRAIN,2,3
Collisions TYPE_PLAYER,TYPE_SCENERY,2,3

Collisions TYPE_BULLET,TYPE_TERRAIN,2,1
Collisions TYPE_BULLET,TYPE_SCENERY,2,1

Collisions TYPE_TARGET,TYPE_TERRAIN,2,2
Collisions TYPE_TARGET,TYPE_SCENERY,2,2

;******
Const TYPE_TESTCUBE = 30
Global G_testcube = CreateCube()
Global G_testcubestate
EntityRadius G_testcube, 1.0
EntityType G_testcube, 30
Collisions TYPE_PLAYER,TYPE_TESTCUBE,1,1
Collisions TYPE_TESTCUBE,TYPE_PLAYER,1,1
;******

Global water_level=-98
Global light,castle,land,ground,water,sky
Global spark_sprite,bull_sprite,player_model,hole_sprite,tree_sprite
Global bull_x#=1.5

Setup()

ChangeDir "environ"
LoadEnviron( "terrain-1.jpg","water-2_mip.bmp","sky","heightmap_256.bmp" )
ChangeDir "..\"

player1.Player=CreatePlayer( 0,10,0 )
camera1.ChaseCam=CreateChaseCam( player1\entity )

period=1000/FPS
time=MilliSecs()-period

listener=CreateListener( player1\entity,.1,1,.2 )
piv=CreatePivot()
PositionEntity piv,0,10,40

While Not KeyHit(1)

	G_millisecs = MilliSecs() ; Code added.

;	If KeyHit(17)
;		wire=Not wire
;		Wireframe wire
;	EndIf
	Repeat
		elapsed=MilliSecs()-time
	Until elapsed

	;how many 'frames' have elapsed	
	ticks=elapsed/period
	
	;fractional remainder
	tween#=Float(elapsed Mod period)/Float(period)
	
	For k=1 To ticks
		time=time+period
		
;******
If G_testcubestate
	PositionEntity G_testcube, 5.0, 5.0, 20.0
	ResetEntity G_testcube
Else
	PositionEntity G_testcube, -5.0, 5.0, 20.0
	ResetEntity G_testcube
EndIf
G_testcubestate = Not G_testcubestate
;******
		
		If k=ticks Then CaptureWorld

		TurnEntity piv,0,5,0
		PositionEntity piv,0,7,40;47+Sin(time*.1)*40,40
		
		UpdateGame()
		UpdateWorld
		PositionEntity water,Sin(time*.01)*10,water_level+Sin(time*.05)*.5,Cos(time*.02)*10
		For c.ChaseCam=Each ChaseCam
			UpdateChaseCam( c )
			;PositionEntity sky,EntityX(c\camera),EntityY(c\camera),EntityZ(c\camera)
		Next
	Next
	
	; -- Code added.
	RenderWorld tween
	Color 200, 0, 0
	Text 10, 10, "W, A, S, D keys to move. Left mouse to fire. Escape to quit."
	Text 10, 30, "Page-up/page-down keys to adjust the restitution value when the smart cam is off."
	Text 10, 50, "Enter key to turn the smart cam on and off."
	Text 10, 80, "Collisions and jumping in smart cam mode cause."
	Text 10, 100, "the cam to switch to a soft restitution value."
	Text 10, 120, "It will then slowly resolve back to a hard restitution value."


	
	If G_smart_cam_flag
		Text 10, 160, "Smart cam is on"
		Text 10, 180, "Restitution = " + G_smart_cam_restitution#
	Else
		Text 10, 160, "Smart cam is off"
		Text 10, 180, "Restitution = " + G_restitution#
	EndIf
	;^^^^^^
	
	Flip
	
Wend

End

Function UpdateGame()
	For h.Hole=Each Hole
		UpdateHole( h )
	Next
	For b.Bullet=Each Bullet
		UpdateBullet( b )
	Next
	For s.Spark=Each Spark
		UpdateSpark( s )
	Next
	For p.Player=Each Player
		UpdatePlayer( p )
	Next
End Function

Function UpdateHole( h.Hole )
	h\alpha=h\alpha-.005
	If h\alpha>0
		EntityAlpha h\sprite,h\alpha
	Else
		FreeEntity h\sprite
		Delete h
	EndIf
End Function

Function CreatePlayer.Player( x#,y#,z# )
	p.Player=New Player
	p\entity=CreatePivot()
	p\model=CopyEntity( player_model,p\entity )
	p\player_y=y
	PositionEntity p\entity,x,y,z
	EntityType p\entity,TYPE_PLAYER
	EntityRadius p\entity,1.5
	ResetEntity p\entity
	Return p
End Function

Function CreateBullet.Bullet( p.Player )
	bull_x=-bull_x
	b.Bullet=New Bullet
	b\time_out=150
	b\sprite=CopyEntity( bull_sprite,p\entity )
	TranslateEntity b\sprite,bull_x,1,.25
	EntityParent b\sprite,0
	EmitSound shoot,b\sprite
	Return b
End Function

Function UpdateBullet( b.Bullet )
	If CountCollisions( b\sprite )
		If EntityCollided( b\sprite,TYPE_TERRAIN )
			EmitSound boom,b\sprite
			ex#=EntityX(b\sprite)
			ey#=EntityY(b\sprite)
			ez#=EntityZ(b\sprite)
			TFormPoint( ex,ey,ez,0,land )
			hi#=TerrainHeight( land,TFormedX(),TFormedZ() )
			If hi>0
				hi=hi-.02:If hi<0 Then hi=0
				ModifyTerrain land,TFormedX(),TFormedZ(),hi,True
			EndIf
			CreateSpark( b )
			FreeEntity b\sprite
			Delete b
			Return
		EndIf
		If EntityCollided( b\sprite,TYPE_SCENERY )
			For k=1 To CountCollisions( b\sprite )
				If GetEntityType( CollisionEntity( b\sprite,k ) )=TYPE_SCENERY
					cx#=CollisionX( b\sprite,k )
					cy#=CollisionY( b\sprite,k )
					cz#=CollisionZ( b\sprite,k )
					nx#=CollisionNX( b\sprite,k )
					ny#=CollisionNY( b\sprite,k )
					nz#=CollisionNZ( b\sprite,k )
					th.Hole=New Hole
					th\alpha=1
					th\sprite=CopyEntity( hole_sprite )
					PositionEntity th\sprite,cx,cy,cz
					AlignToVector th\sprite,-nx,-ny,-nz,3
					MoveEntity th\sprite,0,0,-.1
					Exit
				EndIf
			Next
			EmitSound boom,b\sprite
			CreateSpark( b )
			FreeEntity b\sprite
			Delete b
			Return
		EndIf
	EndIf
	b\time_out=b\time_out-1
	If b\time_out=0
		FreeEntity b\sprite
		Delete b
		Return
	EndIf
	b\rot=b\rot+30
	RotateSprite b\sprite,b\rot
	MoveEntity b\sprite,0,0,2
End Function

Function CreateSpark.Spark( b.Bullet )
	s.Spark=New Spark
	s\alpha=-90
	s\sprite=CopyEntity( spark_sprite,b\sprite )
	EntityParent s\sprite,0
	Return s
End Function

Function UpdateSpark( s.Spark )
	If s\alpha<270
		sz#=Sin(s\alpha)*5+5
		ScaleSprite s\sprite,sz,sz
		RotateSprite s\sprite,Rnd(360)
		s\alpha=s\alpha+15
	Else
		FreeEntity s\sprite
		Delete s
	EndIf
End Function

Function UpdatePlayer( p.Player )

	If MouseDown( 1 )	;fire?
		CreateBullet( p )
	EndIf
	
	If KeyDown( C_KEY_A )	;left/right
		TurnEntity p\entity,0,4,0	;turn player left/right
	Else If KeyDown( C_KEY_D )
		TurnEntity p\entity,0,-4,0
	EndIf
	
	If KeyDown( C_KEY_W )		;forward
		If p\anim_speed<=0
			p\anim_speed=1.75
			Animate p\model,1,p\anim_speed
		EndIf
		MoveEntity p\entity,0,0,1
	Else If KeyDown( C_KEY_S )	;back
		If p\anim_speed>=0
			p\anim_speed=-1.75
			Animate p\model,1,p\anim_speed
		EndIf
		MoveEntity p\entity,0,0,-1
	Else If p\anim_speed	;stop animating
		p\anim_speed=0
		Animate p\model,0
	EndIf

	Goto skip	
	ex#=EntityX(p\entity):ez#=EntityZ(p\entity)
	PositionEntity p\entity,ex,TerrainY( land,ex,0,ez )+1.5,ez
	Return
	.skip
	
	ty#=EntityY(p\entity)
	y_vel#=(ty-p\player_y)
	p\player_y=ty
	
	If KeyHit( C_KEY_SPACE )	;jump?
		y_vel=5	;2.4
		;If G_smart_cam_flag Then G_smart_cam_restitution# = 0.1 ; Code added.
	Else
		y_vel=y_vel-.5	;2
	EndIf
	TranslateEntity p\entity,0,y_vel,0
	
End Function

Function CreateChaseCam.ChaseCam( entity )
	c.ChaseCam=New ChaseCam
	c\entity=entity
	c\camera=CreateCamera()
	
	c\target=CreatePivot( entity )
	PositionEntity c\target,0,3,-10
	EntityType c\target,TYPE_TARGET
	
	c\heading=CreatePivot( entity )
	PositionEntity c\heading,0,0,20
	c\sky=CopyEntity( sky )
	Return c
End Function

Function UpdateChaseCam( c.ChaseCam )


	If KeyDown(200)
		TranslateEntity c\heading,0,-3,0
	Else If KeyDown(208)
		TranslateEntity c\heading,0,+3,0
	EndIf
	
	dx#=EntityX(c\target,True)-EntityX(c\camera,True)
	dy#=EntityY(c\target,True)-EntityY(c\camera,True)
	dz#=EntityZ(c\target,True)-EntityZ(c\camera,True)
	
	;TranslateEntity c\camera, dx * 0.1, dy * 0.1, dz * 0.1	
	
	; -- Code added.
	If KeyHit( 28 ) Then G_smart_cam_flag = Not G_smart_cam_flag
	
	If G_smart_cam_flag
	
		If CountCollisions( c\target )
			G_smart_cam_restitution# = 0.1
		EndIf
		G_smart_cam_restitution# = G_smart_cam_restitution# + C_SMART_CAM_RESTITUTION_INCREMENT#
		If G_smart_cam_restitution# > 1.0 Then G_smart_cam_restitution# = 1.0
		TranslateEntity c\camera, dx * G_smart_cam_restitution#, dy * 0.1, dz * G_smart_cam_restitution#
	
	Else
	
		If KeyDown( 201 )	; page up - harder cam restitution
			G_restitution# = G_restitution# + C_RESTITUTION_INCREMENT#
			If G_restitution# > 1.0 Then G_restitution# = 1.0
		Else If KeyDown( 209 ) ; page down - softer cam restitution
			G_restitution# = G_restitution# - C_RESTITUTION_INCREMENT#
			If G_restitution# < 0.1 Then G_restitution# = 0.1
		EndIf
	
		TranslateEntity c\camera, dx * G_restitution#, dy * 0.1, dz * G_restitution#
	
	EndIf
	;^^^^^^
	
	
	PointEntity c\camera,c\heading
		
	PositionEntity c\target,0,0,0
	ResetEntity c\target
	PositionEntity c\target,0,3,-10

	PositionEntity c\sky,EntityX(c\camera),EntityY(c\camera),EntityZ(c\camera)
End Function

Function LoadEnviron( land_tex$,water_tex$,sky_tex$,height_map$ )

	light=CreateLight()
	TurnEntity light,45,45,0
	
	land_tex=LoadTexture( land_tex$,1 )
	ScaleTexture land_tex,10,10

	land=LoadTerrain( height_map$ )
	EntityTexture land,land_tex
	
	TerrainShading land,True
	PositionEntity land,-1000,-100,-1000
	ScaleEntity land,2000.0/256,100,2000.0/256
	EntityType land,TYPE_TERRAIN
	TerrainDetail land,750,True
	
	For k=1 To n_trees
		Repeat
			tx#=Rnd(-70,70)-150
			tz#=Rnd(-70,70)+400
			ty#=TerrainY( land,tx,0,tz )
		Until ty>water_level
		t=CopyEntity( tree_sprite )
		PositionEntity t,tx,ty,tz
		ScaleSprite t,Rand(2,3),Rand(4,6)
	Next
	
	ground=CreatePlane()
	EntityTexture ground,land_tex
	PositionEntity ground,0,-100,0
	EntityOrder ground,9
	
	water_tex=LoadTexture( water_tex$,3 )
	ScaleTexture water_tex,20,20
	
	water=CreatePlane()
	EntityTexture water,water_tex
	PositionEntity water,0,water_level,0
		
	sky=LoadSkyBox( sky_tex$ )
	EntityOrder sky,10
	HideEntity sky

End Function

Function LoadSkyBox( file$ )
	m=CreateMesh()
	;front face
	b=LoadBrush( file$+"_FR.jpg",49 )
	s=CreateSurface( m,b )
	AddVertex s,-1,+1,-1,0,0:AddVertex s,+1,+1,-1,1,0
	AddVertex s,+1,-1,-1,1,1:AddVertex s,-1,-1,-1,0,1
	AddTriangle s,0,1,2:AddTriangle s,0,2,3
	FreeBrush b
	;right face
	b=LoadBrush( file$+"_LF.jpg",49 )
	s=CreateSurface( m,b )
	AddVertex s,+1,+1,-1,0,0:AddVertex s,+1,+1,+1,1,0
	AddVertex s,+1,-1,+1,1,1:AddVertex s,+1,-1,-1,0,1
	AddTriangle s,0,1,2:AddTriangle s,0,2,3
	FreeBrush b
	;back face
	b=LoadBrush( file$+"_BK.jpg",49 )
	s=CreateSurface( m,b )
	AddVertex s,+1,+1,+1,0,0:AddVertex s,-1,+1,+1,1,0
	AddVertex s,-1,-1,+1,1,1:AddVertex s,+1,-1,+1,0,1
	AddTriangle s,0,1,2:AddTriangle s,0,2,3
	FreeBrush b
	;left face
	b=LoadBrush( file$+"_RT.jpg",49 )
	s=CreateSurface( m,b )
	AddVertex s,-1,+1,+1,0,0:AddVertex s,-1,+1,-1,1,0
	AddVertex s,-1,-1,-1,1,1:AddVertex s,-1,-1,+1,0,1
	AddTriangle s,0,1,2:AddTriangle s,0,2,3
	FreeBrush b
	;top face
	b=LoadBrush( file$+"_UP.jpg",49 )
	s=CreateSurface( m,b )
	AddVertex s,-1,+1,+1,0,1:AddVertex s,+1,+1,+1,0,0
	AddVertex s,+1,+1,-1,1,0:AddVertex s,-1,+1,-1,1,1
	AddTriangle s,0,1,2:AddTriangle s,0,2,3
	FreeBrush b
	;bottom face	
	b=LoadBrush( file$+"_DN.jpg",49 )
	s=CreateSurface( m,b )
	AddVertex s,-1,-1,-1,1,0:AddVertex s,+1,-1,-1,1,1
	AddVertex s,+1,-1,+1,0,1:AddVertex s,-1,-1,+1,0,0
	AddTriangle s,0,1,2:AddTriangle s,0,2,3
	FreeBrush b
	ScaleMesh m,100,100,100
	FlipMesh m
	EntityFX m,1
	Return m
End Function

Function Setup()

	castle=LoadMesh( "castle\castle1.x" )
	ScaleEntity castle,.15,.15,.15
	EntityType castle,TYPE_SCENERY

	player_model=LoadAnimMesh( "markio\mariorun.x" )
	ScaleEntity player_model,.2,.2,.2
	TranslateEntity player_model,0,-1.25,0
	HideEntity player_model

	spark_sprite=LoadSprite( "sprites\bigspark.bmp" )
	HideEntity spark_sprite

	bull_sprite=LoadSprite( "sprites\bluspark.bmp" )
	ScaleSprite bull_sprite,3,3
	EntityRadius bull_sprite,1.5
	EntityType bull_sprite,TYPE_BULLET
	HideEntity bull_sprite
	
	hole_sprite=LoadSprite( "sprites\bullet_hole.bmp",1 )
	EntityBlend hole_sprite,2
	SpriteViewMode hole_sprite,2
	HideEntity hole_sprite
	
	tree_sprite=LoadSprite( "sprites\tree.bmp",7 )
	HandleSprite tree_sprite,0,-1
	ScaleSprite tree_sprite,2,4
	PositionEntity tree_sprite,0,0,-100
	SpriteViewMode tree_sprite,3
	EntityAutoFade tree_sprite,120,150
End Function

blackbag

(Posted 2008) [#3]

Brilliant & Thanks,

I split the two functions, updating the position based upon velocity (the translateentity command at the end) and the repositioning code, and ran them a different parts of the main loop, before and after capture world.

Works perfectly now.

I think my problem is I kinda understand what the tweening code is attempting to do, without really understanding the detail.