Need help converting model to triangles!

[DruggedBunnyParticipant]

I’m really struggling with visualising the whole mesh/vertex/index/triangle thing!

It doesn’t help that I don’t really understand what the indices are, and how they relate to triangles…

So far I have a ModelFromTriangle:Model function (at the top) that takes a model and attempts to return a single triangle from the model’s mesh, but I think even that may be down to poor understanding.

It produces what looks like a cube from a distance (the original gets hidden), but as you approach (A/Z, cursors) it becomes clear I’ve got the wrong end of the stick completely. Moving the model to z=10 even adds a weird black triangle here. Enable the sphere version for an even more bizarre result!

I basically want to see how turning a model into triangles, and then turning those into physics bodies, goes — probably painfully slowly, but ought to look really cool, and worth a try (for my Bust! demo)…

Not taking into account materials or repositioning to match the original at this stage, just trying to recreate the right triangles from the model using a hard-coded material for now…

Monkey

[crayon-5cb9b9d9019ac632067179 inline="true" ] #Import "<std>" #Import "<mojo3d>" Using std.. Using mojo.. Using mojo3d.. Global AppName:String = "My 3D Game" ' TODO: Return array of tri models?? ' Single tri... Function ModelFromTriangle:Model (in_model:Model, index:UInt) Local mesh:Mesh = in_model.Mesh Local tri_model:Model = New Model tri_model.Material = New PbrMaterial (Color.Red) tri_model.Material.CullMode = CullMode.None Assert (index < (mesh.NumIndices - 1) - 2, "index too high") ' Think that's right... Local tri_verts:Vertex3f [] = New Vertex3f [3] ' mesh-local co-ords... tri_verts [0] = mesh.GetVertex (index + 0) tri_verts [1] = mesh.GetVertex (index + 1) tri_verts [2] = mesh.GetVertex (index + 2) Local tri_indices:UInt [] = New UInt [3] tri_indices [0] = 0 tri_indices [1] = 1 tri_indices [2] = 2 Local tri_mesh:Mesh = New Mesh (tri_verts, tri_indices) tri_mesh.AddMesh (tri_mesh) tri_mesh.UpdateNormals () tri_mesh.UpdateTangents () tri_model.Mesh = tri_mesh Return tri_model End Class Game Extends Window Const SHIFT_BOOST:Float = 5.0 Field camera_boost:Float = 1.0 ' Basic 3D scene requirements... Field scene:Scene Field camera:Camera Field light:Light ' Test cube... Field cube:Model Method New (title:String, width:Int, height:Int, flags:WindowFlags) Super.New (title, width, height, flags) scene = Scene.GetCurrent () ' Important! camera = New Camera ' Camera settings... camera.Near = 0.1 ' Camera position... camera.Move (0, 0, -2) 'camera.Viewport = Window.Rect light = New Light light.Move (-10, 10, -10) cube = Model.CreateBox (New Boxf (-0.5, -0.5, -0.5, 0.5, 0.5, 0.5), 1, 1, 1, New PbrMaterial (Color.Aluminum)) ' cube.Rotate (0, 45, 0) ' This is... beautiful! 'cube = Model.CreateSphere (0.5, 32, 32, New PbrMaterial (Color.Aluminum)) Local ticks:Int = Millisecs () For Local loop:UInt = 0 Until cube.Mesh.NumIndices - 3 Step 3 Print loop Local test:Model = ModelFromTriangle (cube, loop) test.Move (0, 0, 10) Next ' Hide original! cube.Visible = False Print Millisecs () - ticks End Method UpdateGame:Void () End Method OnRender (canvas:Canvas) Override ProcessInput () UpdateGame () cube.Rotate (0.0, 1.0, 0.0) ' Tell app to draw frame when ready... RequestRender () ' Render scene to canvas (passed to OnRender by mojo), from camera... scene.Render (canvas) canvas.DrawText ("VP:" + camera.Viewport, 20, 20) End Method ProcessInput:Void () If Keyboard.KeyHit (Key.Space) Then light.CastsShadow = Not light.CastsShadow 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 () ' Windowed mode... ' Local width:Int = 640 ' Local height:Int = 480 ' Local flags:WindowFlags = WindowFlags.Center ' Full-screen mode (comment out above)... Local width:Int = 1024 Local height:Int = 768 Local flags:WindowFlags = WindowFlags.Center'Fullscreen New AppInstance New Game (AppName, width, height, flags) App.Run () End

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[crayon-5cb9b9d9019ac632067179 inline="true" ] #Import "<std>" #Import "<mojo3d>"   Using std.. Using mojo.. Using mojo3d..   Global AppName:String = "My 3D Game"   ' TODO: Return array of tri models??   ' Single tri...   Function ModelFromTriangle:Model (in_model:Model, index:UInt)   Local mesh:Mesh = in_model.Mesh Local tri_model:Model = New Model tri_model.Material = New PbrMaterial (Color.Red) tri_model.Material.CullMode = CullMode.None   Assert (index < (mesh.NumIndices - 1) - 2, "index too high") ' Think that's right... Local tri_verts:Vertex3f [] = New Vertex3f [3] ' mesh-local co-ords... tri_verts [0] = mesh.GetVertex (index + 0) tri_verts [1] = mesh.GetVertex (index + 1) tri_verts [2] = mesh.GetVertex (index + 2) Local tri_indices:UInt [] = New UInt [3] tri_indices [0] = 0 tri_indices [1] = 1 tri_indices [2] = 2 Local tri_mesh:Mesh = New Mesh (tri_verts, tri_indices) tri_mesh.AddMesh (tri_mesh)   tri_mesh.UpdateNormals () tri_mesh.UpdateTangents ()   tri_model.Mesh = tri_mesh   Return tri_model   End   Class Game Extends Window Const SHIFT_BOOST:Float = 5.0 Field camera_boost:Float = 1.0 ' Basic 3D scene requirements... Field scene:Scene Field camera:Camera Field light:Light ' Test cube... Field cube:Model Method New (title:String, width:Int, height:Int, flags:WindowFlags) Super.New (title, width, height, flags) scene = Scene.GetCurrent () ' Important! camera = New Camera ' Camera settings... camera.Near = 0.1 ' Camera position... camera.Move (0, 0, -2) 'camera.Viewport = Window.Rect light = New Light light.Move (-10, 10, -10) cube = Model.CreateBox (New Boxf (-0.5, -0.5, -0.5, 0.5, 0.5, 0.5), 1, 1, 1, New PbrMaterial (Color.Aluminum))   ' cube.Rotate (0, 45, 0)   ' This is... beautiful! 'cube = Model.CreateSphere (0.5, 32, 32, New PbrMaterial (Color.Aluminum)) Local ticks:Int = Millisecs () For Local loop:UInt = 0 Until cube.Mesh.NumIndices - 3 Step 3 Print loop Local test:Model = ModelFromTriangle (cube, loop) test.Move (0, 0, 10) Next ' Hide original! cube.Visible = False Print Millisecs () - ticks End   Method UpdateGame:Void () End Method OnRender (canvas:Canvas) Override ProcessInput () UpdateGame () cube.Rotate (0.0, 1.0, 0.0) ' Tell app to draw frame when ready... RequestRender () ' Render scene to canvas (passed to OnRender by mojo), from camera... scene.Render (canvas)   canvas.DrawText ("VP:" + camera.Viewport, 20, 20) End   Method ProcessInput:Void ()   If Keyboard.KeyHit (Key.Space) Then light.CastsShadow = Not light.CastsShadow   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 () ' Windowed mode... ' Local width:Int = 640 ' Local height:Int = 480 ' Local flags:WindowFlags = WindowFlags.Center ' Full-screen mode (comment out above)... Local width:Int = 1024 Local height:Int = 768 Local flags:WindowFlags = WindowFlags.Center'Fullscreen New AppInstance New Game (AppName, width, height, flags) App.Run () End

[/crayon]

[Simon ArmstrongParticipant]

You need to get the source vertices via their index:

Monkey

#Import "<std>" #Import "<mojo3d>" Using std.. Using mojo.. Using mojo3d.. Global AppName:String = "My 3D Game" ' TODO: Return array of tri models?? ' Single tri... Function ModelFromTriangle:Model (in_model:Model, index:UInt) Local mesh:Mesh = in_model.Mesh Local tri_model:Model = New Model tri_model.Material = New PbrMaterial (Color.Red) tri_model.Material.CullMode = CullMode.None Assert (index + 2 < mesh.NumIndices , "index too high") ' Think that's right... Local indices:=mesh.GetIndices() Local tri_verts:Vertex3f [] = New Vertex3f [3] ' mesh-local co-ords... tri_verts [0] = mesh.GetVertex (indices[index + 0]) tri_verts [1] = mesh.GetVertex (indices[index + 1]) tri_verts [2] = mesh.GetVertex (indices[index + 2]) Local tri_indices:UInt [] = New UInt [3] tri_indices [0] = 0 tri_indices [1] = 1 tri_indices [2] = 2 Local tri_mesh:Mesh = New Mesh (tri_verts, tri_indices) ' tri_mesh.AddMesh (tri_mesh) tri_mesh.UpdateNormals () tri_mesh.UpdateTangents () tri_model.Mesh = tri_mesh Return tri_model End Class Game Extends Window Const SHIFT_BOOST:Float = 5.0 Field camera_boost:Float = 1.0 ' Basic 3D scene requirements... Field scene:Scene Field camera:Camera Field light:Light ' Test cube... Field cube:Model Method New (title:String, width:Int, height:Int, flags:WindowFlags) Super.New (title, width, height, flags) scene = Scene.GetCurrent () ' Important! camera = New Camera ' Camera settings... camera.Near = 0.1 ' Camera position... camera.Move (0, 0, -2) 'camera.Viewport = Window.Rect light = New Light light.Move (-10, 10, -10) ' cube = Model.CreateBox (New Boxf (-0.5, -0.5, -0.5, 0.5, 0.5, 0.5), 1, 1, 1, New PbrMaterial (Color.Aluminum)) ' cube.Rotate (0, 45, 0) ' This is... beautiful! cube = Model.CreateSphere (0.5, 32, 32, New PbrMaterial (Color.Aluminum)) Local ticks:Int = Millisecs () For Local loop:UInt = 0 Until cube.Mesh.NumIndices Step 3 Print loop Local test:Model = ModelFromTriangle (cube, loop) ' test.Move (loop*0.125, 0, 1) test.Move (0, 0, 1) Next ' Hide original! cube.Visible = False Print Millisecs () - ticks End Method UpdateGame:Void () End Method OnRender (canvas:Canvas) Override ProcessInput () UpdateGame () cube.Rotate (0.0, 1.0, 0.0) ' Tell app to draw frame when ready... RequestRender () ' Render scene to canvas (passed to OnRender by mojo), from camera... scene.Render (canvas) canvas.DrawText ("VP:" + camera.Viewport, 20, 20) End Method ProcessInput:Void () If Keyboard.KeyHit (Key.Space) Then light.CastsShadow = Not light.CastsShadow 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 () ' Windowed mode... ' Local width:Int = 640 ' Local height:Int = 480 ' Local flags:WindowFlags = WindowFlags.Center ' Full-screen mode (comment out above)... Local width:Int = 1024 Local height:Int = 768 Local flags:WindowFlags = WindowFlags.Center'Fullscreen 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" ' TODO: Return array of tri models?? ' Single tri... Function ModelFromTriangle:Model (in_model:Model, index:UInt) Local mesh:Mesh = in_model.Mesh Local tri_model:Model = New Model tri_model.Material = New PbrMaterial (Color.Red) tri_model.Material.CullMode = CullMode.None Assert (index + 2 < mesh.NumIndices , "index too high") ' Think that's right... Local indices:=mesh.GetIndices() Local tri_verts:Vertex3f [] = New Vertex3f [3] ' mesh-local co-ords... tri_verts [0] = mesh.GetVertex (indices[index + 0]) tri_verts [1] = mesh.GetVertex (indices[index + 1]) tri_verts [2] = mesh.GetVertex (indices[index + 2]) Local tri_indices:UInt [] = New UInt [3] tri_indices [0] = 0 tri_indices [1] = 1 tri_indices [2] = 2 Local tri_mesh:Mesh = New Mesh (tri_verts, tri_indices) ' tri_mesh.AddMesh (tri_mesh) tri_mesh.UpdateNormals () tri_mesh.UpdateTangents () tri_model.Mesh = tri_mesh Return tri_model End Class Game Extends Window Const SHIFT_BOOST:Float = 5.0 Field camera_boost:Float = 1.0 ' Basic 3D scene requirements... Field scene:Scene Field camera:Camera Field light:Light ' Test cube... Field cube:Model Method New (title:String, width:Int, height:Int, flags:WindowFlags) Super.New (title, width, height, flags) scene = Scene.GetCurrent () ' Important! camera = New Camera ' Camera settings... camera.Near = 0.1 ' Camera position... camera.Move (0, 0, -2) 'camera.Viewport = Window.Rect light = New Light light.Move (-10, 10, -10) ' cube = Model.CreateBox (New Boxf (-0.5, -0.5, -0.5, 0.5, 0.5, 0.5), 1, 1, 1, New PbrMaterial (Color.Aluminum)) ' cube.Rotate (0, 45, 0) ' This is... beautiful! cube = Model.CreateSphere (0.5, 32, 32, New PbrMaterial (Color.Aluminum)) Local ticks:Int = Millisecs () For Local loop:UInt = 0 Until cube.Mesh.NumIndices Step 3 Print loop Local test:Model = ModelFromTriangle (cube, loop) ' test.Move (loop*0.125, 0, 1) test.Move (0, 0, 1) Next ' Hide original! cube.Visible = False Print Millisecs () - ticks End Method UpdateGame:Void () End Method OnRender (canvas:Canvas) Override ProcessInput () UpdateGame () cube.Rotate (0.0, 1.0, 0.0) ' Tell app to draw frame when ready... RequestRender () ' Render scene to canvas (passed to OnRender by mojo), from camera... scene.Render (canvas) canvas.DrawText ("VP:" + camera.Viewport, 20, 20) End Method ProcessInput:Void () If Keyboard.KeyHit (Key.Space) Then light.CastsShadow = Not light.CastsShadow 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 () ' Windowed mode... ' Local width:Int = 640 ' Local height:Int = 480 ' Local flags:WindowFlags = WindowFlags.Center ' Full-screen mode (comment out above)... Local width:Int = 1024 Local height:Int = 768 Local flags:WindowFlags = WindowFlags.Center'Fullscreen New AppInstance New Game (AppName, width, height, flags) App.Run () End

[DruggedBunnyParticipant]

Ahhhh… thanks, Simon, that’s awesome, will try take it in, but I can at least get to work now! Thanks again.

[DruggedBunnyParticipant]

Getting somewhere with this, with a lot of hand-waving…

Shatter!

Source

Messy and still needs a lot of work, eg. triangles’ physics bodies are boxes so they don’t settle right (think I will try build rects from them instead), but at least the ball’s disintegration looks sort-of OK. Ideally it would disintegrate as each triangle intersects the ground, instead of the instant the ball touches the ground, but it’s basically doing what I was hoping for.

The triangles seem to disappear initially, but I think it’s because they turn edge-on, being infinitely thin.

Bit slow on WebGL, unsurprisingly.

In real life, triangles would be replaced with pre-generated model chunks.

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