portal-style portals

Blitz3D Forums/Blitz3D Programming/portal-style portals

Wigwam

(Posted 2009) [#1]

OK, I'm gonna be forced to ask a really open ended question- but I want an effect that will allow me to create a "portal", (like in the game portal)
in other words, a surface that looks as if it's just a regular door, but the room behind it is actually stored somewhere else. I was thinking of doing something with multiple cameras and projecting them onto surfaces, but I can't get that right either.

so... I decided to ask for help because I just don't know how to go about doing it. thanks in advance if you know how to do this..

Mortiis

(Posted 2009) [#2]

You need render to texture, which you can have with FastExt library. You will just place a second camera where the portal opens to, and render that camera to the portal texture.

Gabriel

(Posted 2009) [#3]

You need render to texture

No you don't. You can just render as normal and use CopyRect to copy to a texture. FastExt might be faster (might meaning I have no idea, I've never used it) but it's certainly not required.

Nate the Great

(Posted 2009) [#4]

what you need to do for a cool door effect is something like this.

render camera in the other room from an equivalent position/rotation and copyrect to texture. Then get the projected x and y of each corner of the door. You can use this to set the UV coords for the texture. I may get an example up later. If your door is partially offscreen then it doesnt work an your out of luck. So I dont think there is a bugless way to do it when its partially offscreen.

you can also try cubemapping to another room. :)

Nate the Great

(Posted 2009) [#5]

here is an example!

use left/right arrows to turn camera

Graphics3D 640,480,0,2

campiv = CreatePivot()
cam = CreateCamera(campiv)

lit = CreateLight()
TurnEntity lit,90,0,0

MoveEntity cam,0,0,-20

portalcampiv = CreatePivot()
MoveEntity portalcampiv,0,0,-980
portalcam = CreateCamera()
EntityParent portalcam,portalcampiv
MoveEntity portalcam,0,0,-1000
testcube = CreateCube()
MoveEntity testcube,0,0,-970

porttex = CreateTexture(512,512)


portal = CreateMesh()
surf = CreateSurface(portal)
v1 = AddVertex(surf,-5,5,0,0,0)
v2 = AddVertex(surf,-5,-5,0,0,1)
v3 = AddVertex(surf,5,-5,0,1,1)
v4 = AddVertex(surf,5,5,0,1,0)

AddTriangle surf,v1,v4,v2
AddTriangle surf,v4,v3,v2

UpdateNormals portal

cup = CreateCube()
EntityColor cup,0,0,255
ScaleEntity cup,5.3,.3,.3
MoveEntity cup,0,5,0

cdn = CreateCube()
EntityColor cdn,0,0,255
ScaleEntity cdn,5.3,.3,.3
MoveEntity cdn,0,-5,0

clf = CreateCube()
EntityColor clf,0,0,255
ScaleEntity clf,.3,5.3,.3
MoveEntity clf,-5,0,0

crg = CreateCube()
EntityColor crg,0,0,255
ScaleEntity crg,.3,5.3,.3
MoveEntity crg,5,0,0

TurnEntity testcube,45,0,0

EntityTexture portal,porttex
While Not KeyDown(1)
Cls

If KeyDown(205)
TurnEntity portalcampiv,0,3,0
TurnEntity campiv,0,3,0
ElseIf KeyDown(203)
TurnEntity portalcampiv,0,-3,0
TurnEntity campiv,0,-3,0
EndIf

TurnEntity testcube,2,2,0

CameraProject(cam,-5,5,0)
uvx = ProjectedX()
uvy = ProjectedY()

VertexTexCoords(surf,v1,uvx/640.0,uvy/480.0)

CameraProject(cam,-5,-5,0)
uvx = ProjectedX()
uvy = ProjectedY()

VertexTexCoords(surf,v2,uvx/640.0,uvy/480.0)

CameraProject(cam,5,-5,0)
uvx = ProjectedX()
uvy = ProjectedY()

VertexTexCoords(surf,v3,uvx/640.0,uvy/480.0)

CameraProject(cam,5,5,0)
uvx = ProjectedX()
uvy = ProjectedY()

VertexTexCoords(surf,v4,uvx/640.0,uvy/480.0)

;rendering stuff!
HideEntity cam
RenderWorld()
ShowEntity cam
image = CreateImage(640,480)

CopyRect 0,0,640,480,0,0,BackBuffer(),ImageBuffer(image)
img2 = scaleimagefast(image,512,512,True)
FreeImage image
CopyRect 0,0,512,512,0,0,ImageBuffer(img2),TextureBuffer(porttex)
FreeImage img2

HideEntity portalcam
RenderWorld()
ShowEntity portalcam



Flip
Wend
End

Function ScaleImageFast(SrcImage, ScaleX#, ScaleY#, ExactSize=False)

	Local SrcWidth,  SrcHeight
	Local DestWidth, DestHeight
	Local ScratchImage, DestImage
	Local SrcBuffer, ScratchBuffer, DestBuffer
	Local X1, Y1, X2, Y2
	
	; Get the width and height of the source image. 	
		SrcWidth  = ImageWidth(SrcImage)
		SrcHeight = ImageHeight(SrcImage)

	; Calculate the width and height of the dest image, or the scale.
		If ExactSize = False
	
			DestWidth  = Floor(SrcWidth  * ScaleX#)
			DestHeight = Floor(SrcHeight * ScaleY#)
	
		Else
	
			DestWidth  = ScaleX#
			DestHeight = ScaleY#

			ScaleX# = Float(DestWidth)  / Float(SrcWidth)
			ScaleY# = Float(DestHeight) / Float(SrcHeight)
	
		EndIf			

	; If the image does not need to be scaled, just copy the image and exit the function.
		If (SrcWidth = DestWidth) And (SrcHeight = DestHeight) Then Return CopyImage(SrcImage)

	; Create a scratch image that is as tall as the source image, and as wide as the destination image.
		ScratchImage = CreateImage(DestWidth, SrcHeight)
				
	; Create the destination image.
		DestImage = CreateImage(DestWidth, DestHeight) 

	; Get pointers to the image buffers.
		SrcBuffer     = ImageBuffer(SrcImage)
		ScratchBuffer = ImageBuffer(ScratchImage)
		DestBuffer    = ImageBuffer(DestImage)

	; Duplicate columns from source image to scratch image.
		For X2 = 0 To DestWidth-1
			X1 = Floor(X2 / ScaleX#)
			CopyRect X1, 0, 1, SrcHeight, X2, 0, SrcBuffer, ScratchBuffer
		Next
			
	; Duplicate rows from scratch image to destination image.
		For Y2 = 0 To DestHeight-1
			Y1 = Floor(Y2 / ScaleY#)
			CopyRect 0, Y1, DestWidth, 1, 0, Y2, ScratchBuffer, DestBuffer
		Next
						
	; Free the scratch image.
		FreeImage ScratchImage					
						
	; Return the new image.
		Return DestImage
					
End Function

Here is another cooler example

Graphics3D 640,480,0,2

campiv = CreatePivot()
cam = CreateCamera(campiv)

lit = CreateLight()
TurnEntity lit,90,0,0

MoveEntity cam,0,0,-20

realcube = CreateCube()
EntityColor realcube,255,0,0
MoveEntity realcube,0,0,10

portalcampiv = CreatePivot()
MoveEntity portalcampiv,0,0,-980
portalcam = CreateCamera()
EntityParent portalcam,portalcampiv
MoveEntity portalcam,0,0,-1000
testcube = CreateCube()
MoveEntity testcube,0,0,-970

porttex = CreateTexture(512,512)


portal = CreateMesh()
surf = CreateSurface(portal)
v1 = AddVertex(surf,-5,5,0,0,0)
v2 = AddVertex(surf,-5,-5,0,0,1)
v3 = AddVertex(surf,5,-5,0,1,1)
v4 = AddVertex(surf,5,5,0,1,0)

AddTriangle surf,v1,v4,v2
AddTriangle surf,v4,v3,v2

UpdateNormals portal

cup = CreateCube()
EntityColor cup,0,0,255
ScaleEntity cup,5.3,.3,.3
MoveEntity cup,0,5,0

cdn = CreateCube()
EntityColor cdn,0,0,255
ScaleEntity cdn,5.3,.3,.3
MoveEntity cdn,0,-5,0

clf = CreateCube()
EntityColor clf,0,0,255
ScaleEntity clf,.3,5.3,.3
MoveEntity clf,-5,0,0

crg = CreateCube()
EntityColor crg,0,0,255
ScaleEntity crg,.3,5.3,.3
MoveEntity crg,5,0,0

TurnEntity testcube,45,0,0
TurnEntity realcube,45,0,0

EntityTexture portal,porttex
While Not KeyDown(1)
Cls

If KeyDown(205)
TurnEntity portalcampiv,0,3,0
TurnEntity campiv,0,3,0
ElseIf KeyDown(203)
TurnEntity portalcampiv,0,-3,0
TurnEntity campiv,0,-3,0
EndIf

TurnEntity testcube,2,2,0
TurnEntity realcube,2,2,0

CameraProject(cam,-5,5,0)
uvx = ProjectedX()
uvy = ProjectedY()

VertexTexCoords(surf,v1,uvx/640.0,uvy/480.0)

CameraProject(cam,-5,-5,0)
uvx = ProjectedX()
uvy = ProjectedY()

VertexTexCoords(surf,v2,uvx/640.0,uvy/480.0)

CameraProject(cam,5,-5,0)
uvx = ProjectedX()
uvy = ProjectedY()

VertexTexCoords(surf,v3,uvx/640.0,uvy/480.0)

CameraProject(cam,5,5,0)
uvx = ProjectedX()
uvy = ProjectedY()

VertexTexCoords(surf,v4,uvx/640.0,uvy/480.0)

;rendering stuff!
HideEntity cam
RenderWorld()
ShowEntity cam
image = CreateImage(640,480)

CopyRect 0,0,640,480,0,0,BackBuffer(),ImageBuffer(image)
img2 = scaleimagefast(image,512,512,True)
FreeImage image
CopyRect 0,0,512,512,0,0,ImageBuffer(img2),TextureBuffer(porttex)
FreeImage img2

HideEntity portalcam
RenderWorld()
ShowEntity portalcam



Flip
Wend
End

Function ScaleImageFast(SrcImage, ScaleX#, ScaleY#, ExactSize=False)

	Local SrcWidth,  SrcHeight
	Local DestWidth, DestHeight
	Local ScratchImage, DestImage
	Local SrcBuffer, ScratchBuffer, DestBuffer
	Local X1, Y1, X2, Y2
	
	; Get the width and height of the source image. 	
		SrcWidth  = ImageWidth(SrcImage)
		SrcHeight = ImageHeight(SrcImage)

	; Calculate the width and height of the dest image, or the scale.
		If ExactSize = False
	
			DestWidth  = Floor(SrcWidth  * ScaleX#)
			DestHeight = Floor(SrcHeight * ScaleY#)
	
		Else
	
			DestWidth  = ScaleX#
			DestHeight = ScaleY#

			ScaleX# = Float(DestWidth)  / Float(SrcWidth)
			ScaleY# = Float(DestHeight) / Float(SrcHeight)
	
		EndIf			

	; If the image does not need to be scaled, just copy the image and exit the function.
		If (SrcWidth = DestWidth) And (SrcHeight = DestHeight) Then Return CopyImage(SrcImage)

	; Create a scratch image that is as tall as the source image, and as wide as the destination image.
		ScratchImage = CreateImage(DestWidth, SrcHeight)
				
	; Create the destination image.
		DestImage = CreateImage(DestWidth, DestHeight) 

	; Get pointers to the image buffers.
		SrcBuffer     = ImageBuffer(SrcImage)
		ScratchBuffer = ImageBuffer(ScratchImage)
		DestBuffer    = ImageBuffer(DestImage)

	; Duplicate columns from source image to scratch image.
		For X2 = 0 To DestWidth-1
			X1 = Floor(X2 / ScaleX#)
			CopyRect X1, 0, 1, SrcHeight, X2, 0, SrcBuffer, ScratchBuffer
		Next
			
	; Duplicate rows from scratch image to destination image.
		For Y2 = 0 To DestHeight-1
			Y1 = Floor(Y2 / ScaleY#)
			CopyRect 0, Y1, DestWidth, 1, 0, Y2, ScratchBuffer, DestBuffer
		Next
						
	; Free the scratch image.
		FreeImage ScratchImage					
						
	; Return the new image.
		Return DestImage
					
End Function

GIB3D

(Posted 2009) [#6]

Heh, move forward and backwards.

Graphics3D 640,480,0,2

campiv = CreatePivot()
cam = CreateCamera(campiv)

lit = CreateLight()
TurnEntity lit,90,0,0

MoveEntity cam,0,0,-20

realcube = CreateCube()
EntityColor realcube,255,0,0
MoveEntity realcube,0,0,10

portalcampiv = CreatePivot()
MoveEntity portalcampiv,0,0,-980
portalcam = CreateCamera()
EntityParent portalcam,portalcampiv
MoveEntity portalcam,0,0,-1000
testcube = CreateCube()
MoveEntity testcube,0,0,-970

porttex = CreateTexture(512,512)


portal = CreateMesh()
surf = CreateSurface(portal)
v1 = AddVertex(surf,-5,5,0,0,0)
v2 = AddVertex(surf,-5,-5,0,0,1)
v3 = AddVertex(surf,5,-5,0,1,1)
v4 = AddVertex(surf,5,5,0,1,0)

AddTriangle surf,v1,v4,v2
AddTriangle surf,v4,v3,v2

UpdateNormals portal

cup = CreateCube()
EntityColor cup,0,0,255
ScaleEntity cup,5.3,.3,.3
MoveEntity cup,0,5,0

cdn = CreateCube()
EntityColor cdn,0,0,255
ScaleEntity cdn,5.3,.3,.3
MoveEntity cdn,0,-5,0

clf = CreateCube()
EntityColor clf,0,0,255
ScaleEntity clf,.3,5.3,.3
MoveEntity clf,-5,0,0

crg = CreateCube()
EntityColor crg,0,0,255
ScaleEntity crg,.3,5.3,.3
MoveEntity crg,5,0,0

TurnEntity testcube,45,0,0
TurnEntity realcube,45,0,0

EntityTexture portal,porttex
While Not KeyDown(1)
Cls

If KeyDown(205)
TurnEntity portalcampiv,0,3,0
TurnEntity campiv,0,3,0
ElseIf KeyDown(203)
TurnEntity portalcampiv,0,-3,0
TurnEntity campiv,0,-3,0
EndIf

TranslateEntity campiv,0,0,(KeyDown(200)-KeyDown(208))
PositionEntity portalcampiv,EntityX(portalcampiv),EntityY(portalcampiv),-980+EntityZ(campiv)

TurnEntity testcube,2,2,0
TurnEntity realcube,2,2,0

CameraProject(cam,-5,5,0)
uvx = ProjectedX()
uvy = ProjectedY()

VertexTexCoords(surf,v1,uvx/640.0,uvy/480.0)

CameraProject(cam,-5,-5,0)
uvx = ProjectedX()
uvy = ProjectedY()

VertexTexCoords(surf,v2,uvx/640.0,uvy/480.0)

CameraProject(cam,5,-5,0)
uvx = ProjectedX()
uvy = ProjectedY()

VertexTexCoords(surf,v3,uvx/640.0,uvy/480.0)

CameraProject(cam,5,5,0)
uvx = ProjectedX()
uvy = ProjectedY()

VertexTexCoords(surf,v4,uvx/640.0,uvy/480.0)

;rendering stuff!
HideEntity cam
RenderWorld()
ShowEntity cam
image = CreateImage(640,480)

CopyRect 0,0,640,480,0,0,BackBuffer(),ImageBuffer(image)
img2 = ScaleImageFast(image,512,512,True)
FreeImage image
CopyRect 0,0,512,512,0,0,ImageBuffer(img2),TextureBuffer(porttex)
FreeImage img2

HideEntity portalcam
RenderWorld()
ShowEntity portalcam



Flip
Wend
End

Function ScaleImageFast(SrcImage, ScaleX#, ScaleY#, ExactSize=False)

	Local SrcWidth,  SrcHeight
	Local DestWidth, DestHeight
	Local ScratchImage, DestImage
	Local SrcBuffer, ScratchBuffer, DestBuffer
	Local X1, Y1, X2, Y2
	
	; Get the width and height of the source image. 	
		SrcWidth  = ImageWidth(SrcImage)
		SrcHeight = ImageHeight(SrcImage)

	; Calculate the width and height of the dest image, or the scale.
		If ExactSize = False
	
			DestWidth  = Floor(SrcWidth  * ScaleX#)
			DestHeight = Floor(SrcHeight * ScaleY#)
	
		Else
	
			DestWidth  = ScaleX#
			DestHeight = ScaleY#

			ScaleX# = Float(DestWidth)  / Float(SrcWidth)
			ScaleY# = Float(DestHeight) / Float(SrcHeight)
	
		EndIf			

	; If the image does not need to be scaled, just copy the image and exit the function.
		If (SrcWidth = DestWidth) And (SrcHeight = DestHeight) Then Return CopyImage(SrcImage)

	; Create a scratch image that is as tall as the source image, and as wide as the destination image.
		ScratchImage = CreateImage(DestWidth, SrcHeight)
				
	; Create the destination image.
		DestImage = CreateImage(DestWidth, DestHeight) 

	; Get pointers to the image buffers.
		SrcBuffer     = ImageBuffer(SrcImage)
		ScratchBuffer = ImageBuffer(ScratchImage)
		DestBuffer    = ImageBuffer(DestImage)

	; Duplicate columns from source image to scratch image.
		For X2 = 0 To DestWidth-1
			X1 = Floor(X2 / ScaleX#)
			CopyRect X1, 0, 1, SrcHeight, X2, 0, SrcBuffer, ScratchBuffer
		Next
			
	; Duplicate rows from scratch image to destination image.
		For Y2 = 0 To DestHeight-1
			Y1 = Floor(Y2 / ScaleY#)
			CopyRect 0, Y1, DestWidth, 1, 0, Y2, ScratchBuffer, DestBuffer
		Next
						
	; Free the scratch image.
		FreeImage ScratchImage					
						
	; Return the new image.
		Return DestImage
					
End Function

I added

TranslateEntity campiv,0,0,(KeyDown(200)-KeyDown(208))
PositionEntity portalcampiv,EntityX(portalcampiv),EntityY(portalcampiv),-980+EntityZ(campiv)

Wigwam

(Posted 2009) [#7]

thanks Nate the Great. that code is what I am looking for- and I'll credit you for it if you like. although I'm having a few problems getting that to work in my own engine.

I haven't changed anything about it, apart from the 640*480 graphics to 1024*768 and assigned the portal to a type. I also changed it so the "CameraPick" picks the vertex's actual location so you can move the portal around. it seems to tile the texture whenever you turn the viewpoint, though.

Morbius

(Posted 2009) [#8]

Be sure to check out our own Jeremy Alessi's article on Gamasutra:

http://www.gamasutra.com/view/feature/3770/games_demystified_portal.php

Nate the Great

(Posted 2009) [#9]

@Wigwam - why use camerapick? I dont see how camera pick would help. Try changing it back to cameraproject and it should work.

GIB3D

(Posted 2009) [#10]

@Morbius - That's extremely interesting. It makes me want to pause on my recreation project and try out a portal thing. :D

_33	(Posted 2009) [#11]

That would be cool if it permitted you to travel in the window and that you'd "teleport" to where that portal points to. Then it would be a functionnal portal.

GIB3D

(Posted 2009) [#12]

From what I read, it does. It checks if you're touching the portal, and if you are, it disables your collision. Then if you go in too far, you come out the other side.