Mesh vertices edit

Graphics and GPU Programming Programming

Started by azjata December 07, 2010 10:04 AM

11 comments, last by unbird 13 years, 4 months ago

104

Author

December 07, 2010 10:04 AM

Hello,
I am trying to edit mesh which is 4 sided polygon (a square), which contains 4 faces, each one should have 3 vertexes, I have a function that gets a CustomVertex.PositionColored[], where i have 5 vertexes, I was wondering if it's possible to get 3 vertexes for each mesh face? which should give me 12 vertexes,
here is code i use

 public CustomVertex.PositionColored[] getVerticles(Mesh mesh)        {         verts =(CustomVertex.PositionColored[])mesh.VertexBuffer.Lock(0,typeof(CustomVertex.PositionColored),LockFlags.None,mesh.NumberVertices);         return verts;        }

unbird

8,359

December 07, 2010 02:16 PM

Do you mean something like this ?

  +------+  |\    /|                  | \  / |  |  \/  |  |  /\  |  | /  \ |  |/    \|  +------+

If yes, then there are only five vertices, which is actually the value you get from mesh.NumberVertices.

You could treat them as "isolated" vertices by checking the index buffer: three subsequent indices from the index buffer define the vertices of a face, i.e. a triangle , but in the above case vertices are shared (e.g. the center is shared for all four faces). Changing a shared vertex will change all faces that share it. What do you want to achieve ? Treat the faces individually ? Then you actually have to create a new mesh and duplicate vertices.

azjata

104

Author

December 07, 2010 02:31 PM

Hey, ok that's true, but when I try to change position of any of them except the 0 which is the center I can't really see any changes, I have 3 trackbars which are changing the x,y,z of selected vertex, and it doesn't seem to work with the vertexes how it should look like, I am assuming this is because of that they all share the center, I really don't know

unbird

8,359

December 07, 2010 02:43 PM

Hmmm, well haven't used MDX a long time now and I locked buffers rather through GraphicsStream than with arrays. Anyway, I think you are missing a unlock after you have actually changed the vertices in the array. At least you haven't shown code that does.

Still: Have I understand correctly ? You can change the center but not the other vertices ? This sounds weird. Can you show us all relevant code ? I can't judge yet why this is happening.

azjata

104

Author

December 07, 2010 02:53 PM

here is the code i use for changes

case "trackXx":                    {                        if (inEditMode)                        {                            Vector3 t = editedMeshVertex[num].Position;                            t.X = (float)trk.Value / 100;                            editedMeshVertex[num].Position = t;                           graphicsEngine.getMeshByName(listMesh.SelectedItem.ToString()).ConvertVerticlesToMesh(editedMeshVertex);                        }                        break;                    }                case "trackYy":                    {                       if (inEditMode)                        {                            Vector3 t = editedMeshVertex[num].Position;                            t.Y = (float)trk.Value / 100;                            editedMeshVertex[num].Position = t;                            graphicsEngine.getMeshByName(listMesh.SelectedItem.ToString()).ConvertVerticlesToMesh(editedMeshVertex);                            int i = graphicsEngine.getMeshByName(listMesh.SelectedItem.ToString()).mesh.NumberVertices;                                                   }                        break;                    }                case "trackZz":                    {                        if (inEditMode)                        {                            Vector3 t = editedMeshVertex[num].Position;                            t.Z = (float)trk.Value / 100;                            editedMeshVertex[num].Position = t;                            graphicsEngine.getMeshByName(listMesh.SelectedItem.ToString()).ConvertVerticlesToMesh(editedMeshVertex);                        }                                                break;

graphicsengine.getmeshbyname returns the customvertex.positioncolored, and method convertverticlestomesh, pushes the data back to the mesh, I can make actually some changes to maybe 2 vertexes, but it still works quite strange

public void ConvertVerticlesToMesh(CustomVertex.PositionColored[] vertex)          {              this._mesh.VertexBuffer.SetData(vertex, 0, LockFlags.None);          }

unbird

8,359

December 07, 2010 03:05 PM

First, as stated, if you get/set data through a lock, you need a unlock (later), too.
Second, and I think you ran into the same problem I ran into when working with meshes in SlimDX. DON'T lock/unlock through the exposed VertexBuffer/IndexBuffer properties but rather with the functions from the (Base)Mesh class directly, i.e. LockVertexBuffer, UnlockVertexBuffer or SetVertexBufferData.

azjata

104

Author

December 08, 2010 08:24 AM

Hey, I made the following changes as you mentioned before here is how the code looks right now

 public void ConvertVerticlesToMesh(CustomVertex.PositionColored[] vertex)          {              this._mesh.LockVertexBuffer(LockFlags.None);              this._mesh.VertexBuffer.SetData(vertex, 0, LockFlags.None);              this._mesh.UnlockVertexBuffer();          }

  public CustomVertex.PositionColored[] getVerticles(Mesh mesh)        {                        GraphicsStream gs = mesh.LockVertexBuffer(LockFlags.None);            verts = new CustomVertex.PositionColored[mesh.NumberVertices];            for (int i = 0; i < mesh.NumberVertices; i++)            {             verts=(CustomVertex.PositionColored)gs.Read(typeof(CustomVertex.PositionColored));            }                           mesh.UnlockVertexBuffer();                                    return verts;        }

but nothing really changed, what I have noticed that with some of the vertices, I can change only one coordinate, and for example for the vertex number 1 (still talking about the same geometry), when I change the Z position, it actually acts like X coordinate, and it goes from left to right, I can move the camera around the scene, and It really doesn't go on the Z axis, with the X and Y I can't see no changes at all, even better when I select vertex 2, it still moves the same vertex but now only X works but It acts like a Z axis, the 3rd vertex works like it should I can move it around X, Y, and Z like it should work, the next vertex again doesn't work like I was expecting...
Anyway, I think that there is some strange relationship between the vertexes
created with the Mesh class, like I am using Mesh.polygon function... help me out I am out of clues

azjata

104

Author

December 08, 2010 09:02 AM

I don't know if it will help but here is my render loop

 public void RenderGraphics()        {             _device.Clear(ClearFlags.Target, Color.Gray, 1.0f, 0);            _device.RenderState.CullMode = Cull.None;            _device.RenderState.Ambient = Color.White;            _device.RenderState.Lighting = true;            _device.RenderState.FillMode = fillMode;            _device.BeginScene();            foreach (MeshView mesh in MeshList)            {                mesh.DrawMe();            }            drawGrid();            _device.EndScene();            _device.Present();                 }

here is the DrawMe from MeshList class

public void DrawMe()        {            device.Transform.World =  Matrix.Translation(this._positionXYZ);            this._mesh.DrawSubset(0);        }

unbird

8,359

December 08, 2010 12:04 PM

More code is always better, thanks. The drawing code looks fine, it's rather bare (DrawSubset), I don't suspect the issue coming from there.

Quote:...what I have noticed that with some of the vertices, I can change only one coordinate, and for example for the vertex number 1 (still talking about the same geometry), when I change the Z position, it actually acts like X coordinate...

Hmmmm, that sounds like you got a mixup with the vertex structure. Have you actually checked the mesh uses a vertex that matches PositionColored. How do you get that mesh at all ? Did you load it or create it from buttom up (constructor) ? Really check the mesh's vertex format (BaseMesg.VertexFormat) against the CustomVertex.PositionColored.Format (which is probably Format.Diffuse|Format.Position).

You can also always save a mesh - in this case preferably in text format - to check what's going on.

Apart from that: It's essential to use the debugging capabilities the DX SDK offers, especially when dealing with such weird behaviour: Run your app through PIX and/or try to setup the DirectX debug runtimes (The latter is something I unfortunately never got running in MDX but you might be luckier). If you don't know how to do that: refer to the forum FAQ and the sticky threads to learn more about.

azjata

104

Author

December 08, 2010 12:18 PM

Hey,
Yes, thanks a lot, you were right, I checked the VertexFormat and it is PositionNormal, not PositionColored, sinced I changed that everything works great!
Big big big thanks!! that was very helpfull

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