Texture coordinates

[Polo]

How do you add multiple texture coordinates sets to a mesh, in order to use light maps for instance?

[Comtois]

you can call MeshVertexTextureCoordinate(u, v) multiple times between AddMeshVertex(x, y, z) calls to add multiple texture coordinates to a vertex.

Never tested, you will tell us if it work

[Polo]

How do I then set a texture to use a specific set of texture coordinates then?

[Comtois]

i think you will need a vertex shader

http://www.ogre3d.org/forums/viewtopic.php?f=4&t=23179

If the adjacent faces use the same material, but disagree on the texture coordinates (or normals, or anything else for that matter), then they have to use different vertices. In a shader you can use different UVs to access the same sampler but you'd have to have some way of knowing which to use, and that in itself would burn more space on the vertex and would also require per-vertex branch instructions. On balance, it's much better to duplicate vertices.

http://www.ogre3d.org/forums/viewtopic.php?f=5&t=69057

[Polo]

If the adjacent faces use the same material, but disagree on the texture coordinates (or normals, or anything else for that matter), then they have to use different vertices. In a shader you can use different UVs to access the same sampler but you'd have to have some way of knowing which to use, and that in itself would burn more space on the vertex and would also require per-vertex branch instructions. On balance, it's much better to duplicate vertices.

I just hope this advice doesn't come from an Ogre3d developer... It's such a basic task, cannot this be implemented in the engine without having to spend hours making a shader works?

[Comtois]

this advice come from sinbad 'OGRE Founder' .

It was in 2006, you should do some research to see if there is anything new since.

[Polo]

this advice come from sinbad 'OGRE Founder' .

I hope he's changed his mind, that's the worst advice I've ever read!
No built in per pixel lightning and no built in lightmap support, I'm wondering how Ogre users manage to get lightning working.

[DarkDragon]

i think you will need a vertex shader

No, definately not. It says

In a shader you can use different UVs to access the same sampler [...]

but Polo wants different textures (samplers) with different texture coordinates. The AddMaterialLayer textures are different samplers. He should still try it the way you told him, as it should work then. The first layer gets the first texture coordinate specified. The second one the second ... .

Btw built in per fragment lighting should be already done: MaterialShadingMode(#Material, #PB_Material_Phong). Phong is a slightly modified Gouraud (with specular) based on fragments instead of vertices. <= sorry, mixed shading with illumination

[PMV]

In a material-script, you can define which texture should
use which texture-coordinate-set. To define multiple
texture-coordinate-sets use a 3d-editor that can handle
that. I think blender can do that job, but i haven't tried
that. I had no need for different texture-coordinates and
i'm not a graphic-designer.

phong

Vertex normals are interpolated across the face, and these are used to determine colour at each pixel. Gives a more natural lighting effect but is more expensive and works better at high levels of tessellation. Not supported on all hardware.

for more information about shadows in ogre3d i would recommend the manual:
http://www.ogre3d.org/docs/manual/manua ... ml#Shadows

MFG PMV

[DarkDragon]

phong

Vertex normals are interpolated across the face, and these are used to determine colour at each pixel. Gives a more natural lighting effect but is more expensive and works better at high levels of tessellation. Not supported on all hardware.

for more information about shadows in ogre3d i would recommend the manual:
http://www.ogre3d.org/docs/manual/manua ... ml#Shadows

Oh yes, you're right. There was this difference between shading and illumination. But why are you then talking about shadows? They're part of global illumination not local illumination.

Nevertheless, writing one shader for per pixel lighting shouldn't hurt anyone, as shaders are more or less reusable.

[Comtois]

A quick test using MeshManual.pb example, added MeshVertexTextureCoordinate(u, v) for the base of pyramid.
And i use this materialScript

Code: Select all

material MeshManual
{
	technique
	{
		pass
		{
			texture_unit
			{
				texture Clouds.jpg
				tex_coord_set 0
			}
			texture_unit
			{
				texture Dirt.jpg
				tex_coord_set 1
			}
		}
	}
} 

Code: Select all

;
; ------------------------------------------------------------
;
;   PureBasic - Manual Mesh
;
;    (c) 2003 - Fantaisie Software
;
; ------------------------------------------------------------
;

#CameraSpeed = 1

IncludeFile "Screen3DRequester.pb"

Define.f KeyX, KeyY, MouseX, MouseY

Define.f x, y, z, nx, ny, nz, u, v
Define.l Co
Define.w t1, t2, t3

If InitEngine3D()
  
  Add3DArchive("Data/Textures", #PB_3DArchive_FileSystem)
  Add3DArchive("Data/Scripts", #PB_3DArchive_FileSystem)
  Parse3DScripts()
  
  InitSprite()
  InitKeyboard()
  InitMouse()
  
  If Screen3DRequester()
    
    ; Create a pyramid, manually.. See the DataSection, for more precisions
    ;
    
    Restore Pyramid
    
    CreateMesh(0)
    
    ;Base
    AddSubMesh()
    For i = 0 To 3
      Read.f x : Read.f y : Read.f z
      Read.l Co
      Read.f u : Read.f v
      AddMeshVertex(x, y, z)
      MeshVertexNormal(0, 0, 0)
      MeshVertexColor(Co)
      MeshVertexTextureCoordinate(u, v)
      MeshVertexTextureCoordinate(u, v)
    Next
    
    For i = 0 To 1
      Read.w t1 : Read.w t2 : Read.w t3
      AddMeshFace(t1, t2, t3)
    Next
    
    ;Side
    For k=0 To 3
      
      AddSubMesh()
      For i = 0 To 2
        Read.f x : Read.f y : Read.f z
        Read.l Co
        Read.f u : Read.f v
        AddMeshVertex(x, y, z)
        MeshVertexNormal(0, 0, 0) 
        MeshVertexColor(Co)
        MeshVertexTextureCoordinate(u, v)
      Next i
      Read.w t1 : Read.w t2 : Read.w t3
      AddMeshFace(t1, t2, t3)
      
    Next
    
    FinishMesh()
    NormalizeMesh(0) 
    
    UpdateMeshBoundingBox(0)
    
    GetScriptMaterial(0, "MeshManual")
 
    CreateEntity(0, MeshID(0), MaterialID(0))
    ScaleEntity(0, 400, 200, 400)
    
    CreateCamera(0, 0, 0, 100, 100)
    CameraLocate(0, 0, 0, 1000)
    
    CreateLight(0, RGB(255,255,255), 300, 600, -100)
    AmbientColor(RGB(80, 80, 80))
    
    Repeat
      Screen3DEvents()
      
      If ExamineMouse()
        MouseX = -MouseDeltaX() * #CameraSpeed * 0.05
        MouseY = -MouseDeltaY() * #CameraSpeed * 0.05
      EndIf
      
      If ExamineKeyboard()
        
        If KeyboardPushed(#PB_Key_Left)
          KeyX = -#CameraSpeed 
        ElseIf KeyboardPushed(#PB_Key_Right)
          KeyX = #CameraSpeed 
        Else
          KeyX = 0
        EndIf
        
        If KeyboardPushed(#PB_Key_Up)
          KeyY = -#CameraSpeed 
        ElseIf KeyboardPushed(#PB_Key_Down)
          KeyY = #CameraSpeed 
        Else
          KeyY = 0
        EndIf
        
      EndIf
         
      RotateEntity(0, 1, 0, 0, #PB_Relative)
      
      RotateCamera(0, MouseY, MouseX, 0, #PB_Relative)
      MoveCamera  (0, KeyX, 0, KeyY)
      
      RenderWorld()
      Screen3DStats()      
      FlipBuffers()
    Until KeyboardPushed(#PB_Key_Escape) Or Quit = 1
  EndIf
  
Else
  MessageRequester("Error", "The 3D Engine can't be initialized", 0)
EndIf

End

DataSection
  Pyramid:
  ;Base
  Data.f -0.5,-0.5,0.5  ; position
  Data.l $FF            ; color
  Data.f 0,0            ; UVCoordinate
  
  Data.f 0.5,-0.5,0.5   ; position
  Data.l $FF            ; color 
  Data.f 0,1            ; UVCoordinate
  
  Data.f 0.5,-0.5,-0.5  ; position
  Data.l $FF            ; color
  Data.f 1,1            ; UVCoordinate
  
  Data.f -0.5,-0.5,-0.5 ; position
  Data.l $FF            ; color
  Data.f 1,0            ; UVCoordinate
  
  Data.w 2,1,0          ; Face 
  Data.w 0,3,2          ; Face 
  
  ;-Front
  Data.f 0.5,-0.5,0.5   ; position
  Data.l $FFFFFF        ; color
  Data.f 1,0            ; UVCoordinate
  
  Data.f 0.0,0.5,0.0
  Data.l $FFFFFF
  Data.f 0.5,0.5
  
  Data.f -0.5,-0.5,0.5
  Data.l $FFFFFF
  Data.f 0,0
 
  Data.w 0,1,2         ; Face
  
  ;-Back
  Data.f -0.5,-0.5,-0.5
  Data.l $FFFFFF
  Data.f 0,1
  
  Data.f 0.0,0.5,0.0
  Data.l $FFFFFF
  Data.f 0.5,0.5
  
  Data.f 0.5,-0.5,-0.5
  Data.l $FFFFFF
  Data.f 1,1
  
  Data.w 0,1,2
  
  ;-Left
  Data.f -0.5,-0.5,0.5
  Data.l $FFFFFF
  Data.f 0,0
  
  Data.f 0.0,0.5,0.0
  Data.l $FFFFFF
  Data.f 0.5,0.5
  
  Data.f -0.5,-0.5,-0.5
  Data.l $FFFFFF
  Data.f 0,1
  
  Data.w 0,1,2
  
  ;-Right
  Data.f 0.5,-0.5,-0.5
  Data.l $FFFFFF
  Data.f 1,1
  
  Data.f 0.0,0.5,0.0
  Data.l $FFFFFF
  Data.f 0.5,0.5
  
  Data.f 0.5,-0.5,0.5
  Data.l $FFFFFF
  Data.f 1,0
  
  Data.w 0,1,2
  
EndDataSection

[Polo]

Thanks for your answers - any chance this could be possible using a command instead of a material file?

[Fred]

To do advanced stuffs, scripts are probably mandatory as we can't map all the script features with PB commands, it would be too much. Using scripts allows to leverage most of OGRE without hassle.

[Polo]

To do advanced stuffs, scripts are probably mandatory as we can't map all the script features with PB commands, it would be too much. Using scripts allows to leverage most of OGRE without hassle.

True, though using multiple texture coordinates is not that advanced stuff

[J. Baker]

To do advanced stuffs, scripts are probably mandatory as we can't map all the script features with PB commands, it would be too much. Using scripts allows to leverage most of OGRE without hassle.

True, though using multiple texture coordinates is not that advanced stuff

You add multiple textures to a single mesh in your 3D editor, such as Wings3D or whatever you may use. I did this a few years ago with PB. So PB/OGRE does support this, even years ago. You just need to learn how to create multiple textures in your 3D app.