How does AddVertices work?

[DruggedBunnyParticipant]

I’m attempting to build my own meshes, but I can only get the first triangle to show up.

If you comment out the first call to AddMesh (around line 112, below) the second triangle is correctly shown, but with the first call in place, the second triangle doesn’t appear:

Monkey

#Import "<std>" #Import "<mojo3d>" Using std.. Using mojo.. Using mojo3d.. Global AppName:String = "My 3D Game" Function CreateTri:Mesh (x0:Float = -0.5, y0:Float = 0.5, z0:Float = 0.0, x1:Float = 0.5, y1:Float = -0.5, z1:Float = 0.0, x2:Float = -0.5, y2:Float = -0.5, z2:Float = 0.0) Local verts:Vertex3f [] = New Vertex3f [3] verts [0].position = New Vec3f (x0, y0, z0) verts [1].position = New Vec3f (x1, y1, z1) verts [2].position = New Vec3f (x2, y2, z2) Local indices:UInt [] = New UInt [3] indices [0] = 0 indices [1] = 1 indices [2] = 2 Local mesh:Mesh = New Mesh (verts, indices) Return mesh End Function AddMesh:Void (model:Model, mesh:Mesh, material:PbrMaterial = Null) If Not material material = New PbrMaterial (Color.Grey) Endif If Not model.Mesh model.Mesh = mesh Else ' Assuming just new mesh vertices needed (ie. ADDS to current verts)... ' model is the model being added to... model.Mesh.AddVertices (mesh.GetVertices ()) ' Local verts:Vertex3f[] ' Local v:Vertex3f ' Current mesh vertices (testing if needed as well as new verts!)... ' For v = Eachin model.Mesh.GetVertices() ' verts = verts.Resize (verts.Length + 1) ' verts [verts.Length - 1] = v ' Next ' Passed-in new mesh from which to add vertices... ' For v = Eachin mesh.GetVertices() ' verts = verts.Resize (verts.Length + 1) ' verts [verts.Length - 1] = v ' Next ' model.Mesh.AddVertices (verts) Endif ' Needed?? If Not model.Material Then model.Material = material ' Needed?? model.Mesh.UpdateNormals () model.Mesh.UpdateTangents () End Class Game Extends Window Const SHIFT_BOOST:Float = 5.0 Field camera_boost:Float = 1.0 Field scene:Scene Field camera:Camera Field light:Light Field land:Model Method New (title:String, width:Int, height:Int, flags:WindowFlags) Super.New (title, width, height, flags) scene = Scene.GetCurrent () camera = New Camera camera.Near = 0.1 camera.Move (0, 0, -2) camera.Rotate (0, 0, 0) light = New Light light.Move (-10, 10, -10) land = New Model ' Add new triangles to land model's mesh... AddMesh (land, CreateTri ()) ' Defaults to (-0.5, 0.5, 0.0, 0.5, -0.5, 0.0, -0.5, -0.5, 0.0) AddMesh (land, CreateTri (-0.5, 0.5, 0.0, 0.5, 0.5, 0.0, 0.5, -0.5, 0.0)) light.PointAt (land) End Method UpdateGame:Void () End Method OnRender (canvas:Canvas) Override ProcessInput () UpdateGame () RequestRender () scene.Render (canvas, camera) End Method ProcessInput:Void () If Keyboard.KeyDown (Key.LeftShift) camera_boost = SHIFT_BOOST Else camera_boost = 1.0 Endif If Keyboard.KeyHit (Key.Escape) Then App.Terminate () If Keyboard.KeyDown (Key.A) camera.Move (0.0, 0.0, 0.1 * camera_boost) Endif If Keyboard.KeyDown (Key.Z) camera.Move (0.0, 0.0, -0.1 * camera_boost) Endif If Keyboard.KeyDown (Key.Left) camera.Rotate (0.0, 1.0, 0.0) Endif If Keyboard.KeyDown (Key.Right) camera.Rotate (0.0, -1.0, 0.0) Endif If Keyboard.KeyDown (Key.Up) camera.Rotate (1.0, 0.0, 0.0, True) Endif If Keyboard.KeyDown (Key.Down) camera.Rotate (-1.0, 0.0, 0.0, true) Endif End End Function Main () Local width:Int = 1024 Local height:Int = 768 Local flags:WindowFlags = WindowFlags.Center New AppInstance New Game (AppName, width, height, flags) App.Run () End

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#Import "<std>" #Import "<mojo3d>"   Using std.. Using mojo.. Using mojo3d..   Global AppName:String = "My 3D Game"   Function CreateTri:Mesh (x0:Float = -0.5, y0:Float = 0.5, z0:Float = 0.0, x1:Float = 0.5, y1:Float = -0.5, z1:Float = 0.0, x2:Float = -0.5, y2:Float = -0.5, z2:Float = 0.0)   Local verts:Vertex3f [] = New Vertex3f [3] verts [0].position = New Vec3f (x0, y0, z0) verts [1].position = New Vec3f (x1, y1, z1) verts [2].position = New Vec3f (x2, y2, z2) Local indices:UInt [] = New UInt [3] indices [0] = 0 indices [1] = 1 indices [2] = 2   Local mesh:Mesh = New Mesh (verts, indices) Return mesh End   Function AddMesh:Void (model:Model, mesh:Mesh, material:PbrMaterial = Null) If Not material material = New PbrMaterial (Color.Grey) Endif If Not model.Mesh model.Mesh = mesh Else ' Assuming just new mesh vertices needed (ie. ADDS to current verts)...   ' model is the model being added to... model.Mesh.AddVertices (mesh.GetVertices ()) ' Local verts:Vertex3f[]   ' Local v:Vertex3f ' Current mesh vertices (testing if needed as well as new verts!)... ' For v = Eachin model.Mesh.GetVertices() ' verts = verts.Resize (verts.Length + 1) ' verts [verts.Length - 1] = v ' Next   ' Passed-in new mesh from which to add vertices... ' For v = Eachin mesh.GetVertices() ' verts = verts.Resize (verts.Length + 1) ' verts [verts.Length - 1] = v ' Next ' model.Mesh.AddVertices (verts) Endif   ' Needed?? If Not model.Material Then model.Material = material ' Needed??   model.Mesh.UpdateNormals () model.Mesh.UpdateTangents () End   Class Game Extends Window Const SHIFT_BOOST:Float = 5.0 Field camera_boost:Float = 1.0 Field scene:Scene Field camera:Camera Field light:Light   Field land:Model   Method New (title:String, width:Int, height:Int, flags:WindowFlags) Super.New (title, width, height, flags) scene = Scene.GetCurrent () camera = New Camera camera.Near = 0.1 camera.Move (0, 0, -2)   camera.Rotate (0, 0, 0) light = New Light light.Move (-10, 10, -10)   land = New Model   ' Add new triangles to land model's mesh... AddMesh (land, CreateTri ()) ' Defaults to (-0.5, 0.5, 0.0, 0.5, -0.5, 0.0, -0.5, -0.5, 0.0) AddMesh (land, CreateTri (-0.5, 0.5, 0.0, 0.5, 0.5, 0.0, 0.5, -0.5, 0.0))   light.PointAt (land) End Method UpdateGame:Void () End Method OnRender (canvas:Canvas) Override ProcessInput () UpdateGame () RequestRender () scene.Render (canvas, camera)   End   Method ProcessInput:Void ()   If Keyboard.KeyDown (Key.LeftShift) camera_boost = SHIFT_BOOST Else camera_boost = 1.0 Endif If Keyboard.KeyHit (Key.Escape) Then App.Terminate () If Keyboard.KeyDown (Key.A) camera.Move (0.0, 0.0, 0.1 * camera_boost) Endif If Keyboard.KeyDown (Key.Z) camera.Move (0.0, 0.0, -0.1 * camera_boost) Endif If Keyboard.KeyDown (Key.Left) camera.Rotate (0.0, 1.0, 0.0) Endif If Keyboard.KeyDown (Key.Right) camera.Rotate (0.0, -1.0, 0.0) Endif If Keyboard.KeyDown (Key.Up) camera.Rotate (1.0, 0.0, 0.0, True) Endif If Keyboard.KeyDown (Key.Down) camera.Rotate (-1.0, 0.0, 0.0, true) Endif   End   End Function Main () Local width:Int = 1024 Local height:Int = 768 Local flags:WindowFlags = WindowFlags.Center New AppInstance New Game (AppName, width, height, flags) App.Run () End

Wondered if AddVertices needed ALL vertices (both current mesh verts PLUS the new ones), but that didn’t work either — see commented-out attempt in AddMesh.

By way of explanation, AddMesh takes an existing Model, a new Mesh (received from CreateTriangle) and in theory adds the vertices from that new Mesh to the existing Model, though I don’t know if this is correct/appropriate.

Also not sure if I should be using UpdateNormals, etc… ?

[PakzParticipant]

Mark added a banana that showed how to create a quad mesh. I asked for a example back then. I made several more examples that I have on my monkey2-3d github.

https://github.com/Pakz001/Monkey2-3D

[DruggedBunnyParticipant]

I was actually looking closely at those earlier, Pakz, but a search suggested AddVertices wasn’t part of it — I’m basically trying to add vertices to an existing mesh that I’ve created, rather than create all vertices in one go, which I think all of your samples do.

[Mark SiblyKeymaster]

You need to AddTriangles too – all meshes are currently indexed so you will need to add the triangle indices for any newly added vertices.

In this though, simply going  “model.Mesh.AddTriangles (mesh.GetIndices() )” wont work because you’ll just be adding the same [0,1,2], you’ll need to be trickier.

[edit]I just added AddMesh and it appears to work, ie: instead of addVertices use: model.Mesh.AddMesh( mesh ) which will add vertices and ‘relocated’ indices – draws a quad here anyway.

You’ll have to be a bit cleverer with the model.Materials array too – you’ll need to ‘grow’ this for each added material, in fact maybe it should just be a stack?

Anyway, here’re my tweaks:

Monkey

Function AddMesh:Void (model:Model, mesh:Mesh, material:PbrMaterial = Null) If Not material material = New PbrMaterial (New Color( Rnd(),Rnd(),Rnd() )) Endif If Not model.Mesh model.Mesh = mesh model.Materials=New Material[]( material ) Else model.Mesh.AddMesh( mesh,model.Mesh.NumMaterials ) Local materials:=model.Materials.Resize( model.Materials.Length+1 ) materials[materials.Length-1]=material model.Materials=materials Endif model.Mesh.UpdateNormals () model.Mesh.UpdateTangents () End

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Function AddMesh:Void (model:Model, mesh:Mesh, material:PbrMaterial = Null) If Not material material = New PbrMaterial (New Color( Rnd(),Rnd(),Rnd() )) Endif If Not model.Mesh model.Mesh = mesh model.Materials=New Material[]( material ) Else model.Mesh.AddMesh( mesh,model.Mesh.NumMaterials ) Local materials:=model.Materials.Resize( model.Materials.Length+1 ) materials[materials.Length-1]=material model.Materials=materials Endif model.Mesh.UpdateNormals () model.Mesh.UpdateTangents () End

The future of Model.Material is still up in the air, I may yet rip it out and just leave Model.Materials.

UpdateNormals/Tangents aren’t really needed as AddMesh doesn’t merge vertices so it wont affect existing normals/tangents. Eventually though, there’ll probably be an Optimize() method that will merge vertices and you’ll need to update normals/tangents after that.

Note the Mesh class is really designed for ‘offline’ stuff. In realtime, it’ll be much faster to directly use VertexBuffers and IndexBuffers and to override OnRender.

[DruggedBunnyParticipant]

Thanks, Mark, that’ll do me!

Yeah, I’ve yet to try and grasp materials, but the Material/Materials[] thing is confusing, and I’d thought iterating through Materials[] would be needed to do things properly.

Perhaps Materials[0] could be used as the default and then overridden by the user as they see fit?

Yeah, something that optionally merges vertices would be good.

Not got anywhere near VertexBuffers and co yet! This’ll let me get started on building things myself, then I’ll no doubt move on and try get vertex buffers and co…

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