Raycasting for enemy logic (2d game)

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Thomas John Gorham

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Joined: 23rd Jun 2018

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Posted: 23rd Oct 2020 08:12

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Hi guys,

Im working on another enemy in my game, its a gun with legs.

Anyway, im hoping to use some sort of raycasting, id like to draw a ray between the enemy sprite and the player. I was wondering if there was a command that returns the value of the FIRST sprite that gets hit by the line. Then you can see if an Enemy has the player in its line of sight, or if its blocked by a crate or a wallsprite.

What are the commands to use for something like this? Is this already how it works?

Also, how would you set sprites to not return values if they are hit (for example, floor tiles shouldnt count)

Thanks in Advance
Thomas

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Virtual Nomad

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Location: SF Bay Area, USA

Posted: 23rd Oct 2020 08:35 Edited at: 23rd Oct 2020 09:31

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Quote: "Is this already how it works? "

yes. see SpriteRayCast() , SpriteRayCastGroup() and:

// set window properties
SetWindowSize( 1080, 720, 0 )
SetWindowAllowResize( 1 ) // allow the user to resize the window

// set display properties
SetVirtualResolution( 1080, 720 ) // doesn't have to match the window
SetOrientationAllowed( 1, 1, 1, 1 ) // allow both portrait and landscape on mobile devices
SetSyncRate( 30, 0 ) // 30fps instead of 60 to save battery
SetScissor( 0,0,0,0 ) // use the maximum available screen space, no black borders
UseNewDefaultFonts( 1 ) // since version 2.0.22 we can use nicer default fonts

AddSprites()

x1 = 0	:	y = 116	:	x2 = 600
ThisGroup = 4

do
    If GetRawKeyPressed(32) `[SPACE] 
		If ThisGroup > 0  
			If SpriteRayCastGroup(ThisGroup,x1,y,x2,y) = 1
				x2 = GetRayCastX() 
				DrawLine(x1,y,x2,y,MakeColor(255,0,0), MakeColor(255,0,0))
				DeleteSprite( GetRayCastSpriteID( ))
				DEC ThisGroup
			Endif
		Else
			AddSprites()
			ThisGroup = 4
			x2 = 600
		Endif
	Endif
	
    Print( ThisGroup)
    Sync()
loop

Function AddSprites()
	For x = 1 to 4
		This = CreateSprite(0)	:	SetSpriteSize(This,32,32)	:	SetSpritePosition(This,x*100,100)	:	SetSpriteGroup(This,x)	:	SetSpriteShape(This,2)	
	next x
EndFunction

+ Code Snippet

// set window properties
SetWindowSize( 1080, 720, 0 )
SetWindowAllowResize( 1 ) // allow the user to resize the window

// set display properties
SetVirtualResolution( 1080, 720 ) // doesn't have to match the window
SetOrientationAllowed( 1, 1, 1, 1 ) // allow both portrait and landscape on mobile devices
SetSyncRate( 30, 0 ) // 30fps instead of 60 to save battery
SetScissor( 0,0,0,0 ) // use the maximum available screen space, no black borders
UseNewDefaultFonts( 1 ) // since version 2.0.22 we can use nicer default fonts

AddSprites()

x1 = 0	:	y = 116	:	x2 = 600
ThisGroup = 4

do
    If GetRawKeyPressed(32) `[SPACE] 
		If ThisGroup > 0  
			If SpriteRayCastGroup(ThisGroup,x1,y,x2,y) = 1
				x2 = GetRayCastX() 
				DrawLine(x1,y,x2,y,MakeColor(255,0,0), MakeColor(255,0,0))
				DeleteSprite( GetRayCastSpriteID( ))
				DEC ThisGroup
			Endif
		Else
			AddSprites()
			ThisGroup = 4
			x2 = 600
		Endif
	Endif
	
    Print( ThisGroup)
    Sync()
loop

Function AddSprites()
	For x = 1 to 4
		This = CreateSprite(0)	:	SetSpriteSize(This,32,32)	:	SetSpritePosition(This,x*100,100)	:	SetSpriteGroup(This,x)	:	SetSpriteShape(This,2)	
	next x
EndFunction

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Thomas John Gorham

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Posted: 23rd Oct 2020 09:43

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Dude your like my personal AppGameKit coach now! Thanks

Ive added all my destructables, player, enemies, and wall in one group.

projectiles, floor, dead enemies and broken destructables in another!

its checking for visibility of the player and working!

ThankyoU!

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Thomas John Gorham

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Posted: 28th Nov 2020 04:00

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Hey guys,

does the Raycasting features work of the bounding box shapes defined by setspriteshape? I am having trouble getting my enemy to shoot when im standing next to a wall.

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Virtual Nomad

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Posted: 28th Nov 2020 05:55 Edited at: 28th Nov 2020 06:23

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are you just aiming for the center? consider shooting at the "head" if the player is below then enemy, "feet" otherwise? then, pick a "side" based of above/below? i think you'll need to add this bit of "realism" re: LOS.

that wasn't sound advice... so, i tried shooting at both:

// set window properties
SetWindowTitle( "SpriteCast2" )
SetWindowSize( 1080, 720, 0 )
SetWindowAllowResize( 1 ) // allow the user to resize the window

// set display properties
SetVirtualResolution( 1080, 720 ) // doesn't have to match the window
SetOrientationAllowed( 1, 1, 1, 1 ) // allow both portrait and landscape on mobile devices
SetSyncRate( 30, 0 ) // 30fps instead of 60 to save battery
SetScissor( 0,0,0,0 ) // use the maximum available screen space, no black borders
UseNewDefaultFonts( 1 ) // since version 2.0.22 we can use nicer default fonts

SetPhysicsGravity(0,0)

Enemy = CreateSprite(0)		:	SetSpriteSize(Enemy,32,64)	:	SetSpriteColor(Enemy,128,0,0,255)	:	SetSpritePositionByOffset(Enemy, 100,360)

Global Player as Integer

Player = CloneSprite(Enemy)	:	SetSpriteColor(Player,0,128,0,255)	:	SetSpritePositionByOffset(Player,980,360)
SetSpritePhysicsOn(Player,2)	:	SetSpritePhysicsDamping(Player,1)	:	SetSpritePhysicsCanRotate(Player,0)
	
For x = 0 to 3
	This = CreateSprite(0)	:	SetSpriteSize(This,32,64)	:	SetSpritePositionByOffset(This,540,64 + 192*x)
	SetSpritePhysicsOn(This,1)
Next x

Black = MakeColor(0,0,0)
Red = MakeColor(255,0,0)

do
    UD# = GetJoystickY()			:	If UD# <> 0.0 then UD# = UD#/ABS(UD#)*100.0
    LR# = GetJoystickX()			:	If LR# <> 0.0 then LR# = LR#/ABS(LR#)*100.0
    
    SetSpritePhysicsVelocity(Player,LR#,UD#)
    X# = GetSpriteXByOffset(Player)	:	Y# = GetSpriteYByOffset(Player)
    
    
	Ray = SpriteRayCast(100.0,360.0,X#,Y#-32.0)
	If Ray = 1 
		DrawLine(100,360,GetRayCastX(),GetRayCastY(),Black,Red)
		if GetRayCastSpriteID() = Player then Print("HeadShot")
	Endif

Ray = SpriteRayCast(100.0,360.0,X#,Y#+32.0)
	If Ray = 1 
		DrawLine(100,360,GetRayCastX(),GetRayCastY(),Black,Red)
		if GetRayCastSpriteID() = Player then Print("SweepTheLeg!")
	Endif
	
    Print( ScreenFPS() )
    Sync()
loop

+ Code Snippet

// set window properties
SetWindowTitle( "SpriteCast2" )
SetWindowSize( 1080, 720, 0 )
SetWindowAllowResize( 1 ) // allow the user to resize the window

// set display properties
SetVirtualResolution( 1080, 720 ) // doesn't have to match the window
SetOrientationAllowed( 1, 1, 1, 1 ) // allow both portrait and landscape on mobile devices
SetSyncRate( 30, 0 ) // 30fps instead of 60 to save battery
SetScissor( 0,0,0,0 ) // use the maximum available screen space, no black borders
UseNewDefaultFonts( 1 ) // since version 2.0.22 we can use nicer default fonts

SetPhysicsGravity(0,0)

Enemy = CreateSprite(0)		:	SetSpriteSize(Enemy,32,64)	:	SetSpriteColor(Enemy,128,0,0,255)	:	SetSpritePositionByOffset(Enemy, 100,360)


Global Player as Integer

Player = CloneSprite(Enemy)	:	SetSpriteColor(Player,0,128,0,255)	:	SetSpritePositionByOffset(Player,980,360)
SetSpritePhysicsOn(Player,2)	:	SetSpritePhysicsDamping(Player,1)	:	SetSpritePhysicsCanRotate(Player,0)
	
For x = 0 to 3
	This = CreateSprite(0)	:	SetSpriteSize(This,32,64)	:	SetSpritePositionByOffset(This,540,64 + 192*x)
	SetSpritePhysicsOn(This,1)
Next x

Black = MakeColor(0,0,0)
Red = MakeColor(255,0,0)

do
    UD# = GetJoystickY()			:	If UD# <> 0.0 then UD# = UD#/ABS(UD#)*100.0
    LR# = GetJoystickX()			:	If LR# <> 0.0 then LR# = LR#/ABS(LR#)*100.0
    
    SetSpritePhysicsVelocity(Player,LR#,UD#)
    X# = GetSpriteXByOffset(Player)	:	Y# = GetSpriteYByOffset(Player)
    
    
	Ray = SpriteRayCast(100.0,360.0,X#,Y#-32.0)
	If Ray = 1 
		DrawLine(100,360,GetRayCastX(),GetRayCastY(),Black,Red)
		if GetRayCastSpriteID() = Player then Print("HeadShot")
	Endif

	Ray = SpriteRayCast(100.0,360.0,X#,Y#+32.0)
	If Ray = 1 
		DrawLine(100,360,GetRayCastX(),GetRayCastY(),Black,Red)
		if GetRayCastSpriteID() = Player then Print("SweepTheLeg!")
	Endif
	
    Print( ScreenFPS() )
    Sync()
loop

...and, something's wrong there, too. i think the rays are hitting each other?

i might be a coach, but we'll need a general manager for this one

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