Bump Mapping

Blitz3D Forums/Blitz3D Programming/Bump Mapping

_PJ_	(Posted 2010) [#1]

I know there's a bunch of posts throughout the forums that discuss varous aspects of normal mapping and the simulation of diffuse lighting etc. but I couldn;t find anything specific to exlain clearly just how to go about using the Dot3 blend mode.
Should a bump map be loaded with any specific flags? Can they have alpha? Should they be textureds to the bottom index or on top? Do all R, G and B count towards the resultant 'height'

I've been playing with various applications of multi-texturing all day and it's really been pretty fruitless.

Can anyone help explain just what's really requi9red to get a working bump map combined with other textures?

Graphics3D 1024,768,32,6
SetBuffer BackBuffer()

Global Camera=CreateCamera()
Global Sphere=CreateSphere(100)
Global Applied=True

MoveEntity Camera,0,0,-2

Const FLAG_COLOUR=1
Const FLAG_ALPHA=2
Const FLAG_MASK=4
Const FLAG_MIPMAP=8
Const FLAG_QUALITY=768

Dim Textures(4,1)

Local Itertex
For Itertex=0 To 3
	Textures(Itertex,0)=LoadTexture(TextureLayerName(Itertex)+".dds",FLAG_COLOUR Or FLAG_ALPHA Or FLAG_MIPMAP Or FLAG_QUALITY)
Next	
	
Textures(0,1)=6
Textures(1,1)=6
Textures(2,1)=6
Textures(3,1)=6

Local IterTexture
Local IterTextures

ScaleEntity Sphere,0.5,0.5,0.5

Local TextureInput=0

Global CurrentTextureSelected=0

While Not KeyDown(1)
	
	TextureInput=GetInput()
	If KeyDown(28)
		Sphere=UpdateTextures(Sphere)
	End If
	TurnEntity Sphere,0,0.1,0
	UpdateWorld
	RenderWorld
	
	Color 255,Applied*255,Applied*255
	Text 20,20,"Texture Layer: "+TextureLayerName(CurrentTextureSelected)
	Text 20,40,"Texture Blend: "+TextureBlendModeName(Textures(CurrentTextureSelected,1))
	
	For IterTexture=0 To 3
			Text 20,80+(IterTexture*20),TextureLayerName(Str(IterTexture))+" : "+TextureBlendModeName(Textures(IterTexture,1))
		Next
	Flip
Wend

Function GetInput()
	
	Local NextTexture=KeyHit(205)-KeyHit(203)
	If (NextTexture)
		NextTexture=(CurrentTextureSelected+NextTexture)
		NextTexture=(NextTexture+4) Mod 4
		CurrentTextureSelected=NextTexture
	End If
	Local ChangeBlend=KeyHit(200)-KeyHit(208)
	Local CurrentTextureBlend=Textures(CurrentTextureSelected,1)
	If (ChangeBlend)
		CurrentTextureBlend=(CurrentTextureBlend+ChangeBlend)
		CurrentTextureBlend=(CurrentTextureBlend+7) Mod 7
		Applied=False
	End If	
		Textures(CurrentTextureSelected,1)=CurrentTextureBlend
End Function

Function UpdateTextures(Mesh)
	FreeEntity Mesh
	Mesh=CreateSphere(100)
	Local IterTextures
	For IterTextures=0 To 3
		If (Textures(IterTextures,1)<7)
			TextureBlend Textures(IterTextures,0),Textures(IterTextures,1)
			EntityTexture Mesh,Textures(IterTextures,0),0,IterTextures
		End If
	Next
	Applied=True
	ScaleEntity Sphere,0.5,0.5,0.5
	Return Mesh
End Function

Function TextureBlendModeName$(BlendMode)
	Select BlendMode
		Case 0: Return "Unblended"	
		Case 1: Return "Alpha Only if applicable"	
		Case 2: Return "Multiply"
		Case 3: Return "Add"
		Case 4: Return "Dot3 Bump"
		Case 5: Return "Multiply 2"
		Case 6: Return "Off"
	End Select
End Function


Function TextureLayerName$(Layer)
	Select Layer
		Case 0: Return "bump"
		Case 1: Return "skin"
		Case 2: Return "shadow"
		Case 3: Return "clouds"
	End Select
End Function

jfk EO-11110

(Posted 2010) [#2]

Didn't you find the example that Mark posted when Dot3 was implemented in Blitz? It must be searchable in the Forum I guess.. I remember there was a long discussion. The RGB channels are used for normal info, not like a heightmap. A minute..

Ross C released a heightmap to normalmap converter:
http://www.rosscrooks.pwp.blueyonder.co.uk/height_normal_bb.zip

Might be interesting what Mark said to it:

Hi,

No, there's not much to the update - I have been working on other things which will *eventually* benefit all Blitz products.

There has also been a certain amount of 'politicing' going on behind the scenes over the past year which has consumed far more time than I would have liked.

Cubemapping should be as fast as regular texture mapping. However, dynamically altering cubemaps will be as slow as dynamically altering regular textures. I recommend making sure the mipmap flag isn't set (as any alteration will cause mipmaps to be rebuilt) and/or only refreshing one face per frame or even every N'th frame.

The reason Blitz has never offered a 'render directly to buffer' option is because it is/was broken on many cards/drivers. This situation may have changed by now, but I wouldn't bet on it. This is one of several cases in Blitz3D's design where I have made a deliberate decision to sacrifice (hypothetical) performance for the sake of compatiblity. Such decisions are my call, and I stand by them! Although I understand how others may disagree...

Dot3 blending is 'unofficial'. Blitz3D's current design makes it too tricky to implement proper, generalized dot3 bumpmaps (ie: normals in 'surface space') lit by multiple lights, so I was faced with the decision to either remove plain dot3 blending or leave it in for the community to 'unofficially' play with. I left it in.

Another option would have been to provide some kind of kludge for half-arsed 'one light/object space' dot3 bumpmaps - but I'd rather spend the time working on the real thing.

I am reluctant to charge for Blitz updates, as I would therefore feel obliged to provide them (!) and this would distract me from what I feel is the 'greater good'.

I guess the bottom line is that I have my own intuition of where Blitz needs to go, and you guys are just gonna have to trust me!

Mark

I remember there was a Demo by Fredborg that showed how to make good use from the dot3 feature:
http://home1.stofanet.dk/mfredborg/DotMyBot.zip

Actually, when searching for "dot3" around here, I get a lot of threads. Like http://www.blitzbasic.com/Community/posts.php?topic=46206

Last edited 2010

Rroff

(Posted 2010) [#3]

I brought this up in relation to fastext recently theres a nice way to do it with real time updating unfortunatly I can't find the thread quickly, someone was nice enough to post some fairly ready made code that works great with a few small adaptions.