Multi material object

[Massimo Zanoletti]

Hi to all

I'll use the TGLArrowLine object as a sample to show you what I need.
As you know, ArrowLine is a "single" object; but you can imagine 3 different parts of it: top cap (a cone that is the head); bottom cap (a cone that is the tail) and the line itself (a clylinder).
The ArrowLine object has obviously a material associated to it; this material "paints" all 3 parts with the same material.
And now the question.
I have a single object that is very similar to the ArrowLine (built by different parts), and I would paint each part with different materials.
It's mandatory not to use 3 different separated objects.
Any suggestion to do it?

Thanks in advance
Massimo Zanoletti

[Jerome.D (BeanzMaster)]

Hi Massimo it's depend how you build your object. Do you herit from a TGLObject ? Do you pass thru FreeForms ? DirectOpenGL ?

In your functions take a look a the RenderingContext (RCI) when it's avaible, with you'll can have access to OpenGL's States and others.

With freeform it's easy create 3 SubMesh set UV/Normals according to how you want assign texture (only 1 or 2 or 3)

In Herited object you need play with BuiltList, Render(Object) functions (If i'm remember it's the rights name) and of course play with opengl's functions only with DirectOpenGL

[Massimo Zanoletti]

Thanks for answer.
My object isn't already implemented.
I want to find the best solution to do it.
So, I can consider to use a mesh object.

Probably it should be better if I give more details.
Think to the object as a polygon. Vertexes of polygon will be known at runtime only.
Polygon must be extruded, and the front face must have a material, the side (extrusion) another material, and the back polygon another one again.
Moreover, polygons can have holes.
A good example could be a character; the A for example.

[Jerome.D (BeanzMaster)]

Ok i understand i think the better is TGLMeshObjet. You can take loo at a the attached unit here, it will help you a little :)

[Massimo Zanoletti]

Hi Jerome

I tried with the mesh object
I create different mesh objects and then I insert them into the same FreeForm (it's what I need).
But I can't assign different materials to them
I can only assign the material to whole FreeForm, but in this way all mesh objects will have the same material

[Jerome.D (BeanzMaster)]

Hi Massimo Take a look at the TGLFaceGroup you must create one for each sub object and set MatrerialName property

[Massimo Zanoletti]

Hi Jerome.

I attached a very simple demo app.
I tried but...
There are 2 buttons
The first just create 2 meshes inside the same FreeForm object (and it wokrs)
The second one try to connect to different materials

[Jerome.D (BeanzMaster)]

Hi Massimo simply (LOL) just change

procedure TForm1.BtnConnectMatClick(Sender: TObject);
begin
   // Cylinder should be red
   FrForm1.MeshObjects[0].FaceGroups[0].MaterialName := 'MatRed';
   // Cube should be green
   FrForm1.MeshObjects[1].FaceGroups[0].MaterialName := 'MatGreen';
   FrForm1.MeshObjects[0].FaceGroups[0].PrepareMaterialLibraryCache(MatLibr);
   FrForm1.MeshObjects[1].FaceGroups[0].PrepareMaterialLibraryCache(MatLibr);
end;

by

procedure TForm1.BtnConnectMatClick(Sender: TObject);
begin
   // Cylinder should be red
   FrForm1.MaterialLibrary:=MatLibr;
   FrForm1.MeshObjects[0].FaceGroups[0].MaterialName := 'RedMat';
   // Cube should be green
   FrForm1.MeshObjects[1].FaceGroups[0].MaterialName := 'GreenMat';

   //Prepare matcache for all MESHOBECTS AND FaceGroups. It work but something is wrong with that. 
   // Normaly just the 1st MeshObject's facegroups'MatCache will be altered.

   FrForm1.MeshObjects[0].FaceGroups.PrepareMaterialLibraryCache(MatLibr);   
   // FrForm1.MeshObjects[0].FaceGroups[0].PrepareMaterialLibraryCache(MatLibr);
   // FrForm1.MeshObjects[1].FaceGroups[0].PrepareMaterialLibraryCache(MatLibr);

end;

:)

[Massimo Zanoletti]

Thank you very much, Jerome

[Massimo Zanoletti]

Hi Jerome
I'm back here because I need another little help
Your previous suggestion works fine, but is not exactly what I need.
I had a mistake when in the little sample I used the MeshHelper class objects (I used them just for speed in sample), but in my real application I will not use that class, and unfortunately it seems that your suggestion works only for Helper class.
My real application uses the TGLMeshObject class, but (most important) mesh is built starting from triangles (I have some shapes built by tringles), so the "Mode" is set in momTriangles.
and I don't know how to apply different materials in this situation.

I provided a little sample.
I left the previous code inside, and I added new code to show.
When the check box is checked, the sample works exactly as before, using the Helper class and you suggestion (and it works).
When checkbox is unchecked, the first button builds two meshes starting from triangles (a simple house and a simple arrow), but then the connect material button ...

Please take a look if you can

Thanks in advance
Massimo

[Jerome.D (BeanzMaster)]

Hi Massimo, i taked a quick look first becarefull with material spelling Name in the code you have GreenMat and RedMat but you've declared MatRed and MatGreen in materialLibrary (same error as before)

2nd
` MObjStd2 := TGLMeshObject.CreateOwned (FrForm1.MeshObjects);
MObjStd2.Mode := momTriangles;
MObjStd2.Name := 'Arrow';
MObjStd2.Vertices.Add (AffineVectorMake (2.0, -0.5, 2.0));
MObjStd2.Vertices.Add (AffineVectorMake (5.0, -0.5, 2.0));
MObjStd2.Vertices.Add (AffineVectorMake (2.0, +0.5, 2.0));

MObjStd2.Vertices.Add (AffineVectorMake (2.0, +0.5, 2.0));
MObjStd2.Vertices.Add (AffineVectorMake (5.0, -0.5, 2.0));
MObjStd2.Vertices.Add (AffineVectorMake (5.0, +0.5, 2.0));

MObjStd2.Vertices.Add (AffineVectorMake (5.0, -1.0, 2.0));
MObjStd2.Vertices.Add (AffineVectorMake (6.0, +0.0, 2.0));
MObjStd2.Vertices.Add (AffineVectorMake (5.0, +1.0, 2.0));`

Here is not enought, Here is just one object, no submesh, no faces group so you can only attach ONE material. For what you want, you need to declare Face's indices in a Face's groups for each part of your object

See in GLMeshObjectHelper :

`
constructor TGLCustomEditingMeshObject.Create;
begin
inherited Create;
FFaceList := TFGVertexIndexList.CreateOwned(self.FaceGroups); --> FaceList
FFaceList.Mode := fgmmQuads; // fgmmTriangles; ---> Here is what you search
Mode := momFaceGroups;
self.UseVBO := true;

end;
procedure TGLCustomEditingMeshObject.AddFace(v1, v2, v3: TVector);
var
i1, i2, i3: Integer;
begin
i1 := AddVertice(v1.V[0], v1.V[1], v1.V[2]);
i2 := AddVertice(v2.V[0], v2.V[1], v2.V[2]);
i3 := AddVertice(v3.V[0], v3.V[1], v3.V[2]);
FFaceList.VertexIndices.Add(i1, i2, i3); ---> take a look at this
end;`

For each material in GLMeshObject you'll need to create in order Vertices-->FaceGroups -->FacesList.
And finally set the good material to the right facegroup.

[sxbug]

Hi

[dcc32 Error] glmeshobjecthelper.pas(44): E2003 Undeclared identifier: 'TGLMeshObject'

I am using GLScene 1.7. How can I do? Thanks

[sxbug]

I have changed to TMeshObject, Is it correct?
Thanks

[Pavel Vassiliev]

sxbug,
Yes it is. Renaming to TGLMeshObject needs to change glsm files format for correct saving scenes.
PW

[sxbug]

Hi
I want to make some cross-section with many points (each cross-section make up by 30000 points), each cross-section is set to different colors according to the parameter 'form1.MyRecArray^[i].piancha[j])'. Now the following program is running wrong .How do I modify these code?

procedure TForm2.ConnectMaterialStandard;
begin
GLFreeForm1.MaterialLibrary:=GLMaterialLibrary1;

if MObjStd1<>nil then
GLFreeForm1.MeshObjects[0].FaceGroups[0].MaterialName := 'LimeMat'; //Exception class $C0000005 with message'C0000005 ACCESS_VIOLATION'
if MObjStd2<>nil then
GLFreeForm1.MeshObjects[1].FaceGroups[0].MaterialName := 'YellowMat';
if MObjStd3<>nil then
GLFreeForm1.MeshObjects[2].FaceGroups[0].MaterialName := 'RedMat';
end;

procedure TForm2.CreateMeshStandard(CircleCount:integer);
var
i,j:integer;
begin
for i:=0 to CircleCount-1 do begin
if (abs(form1.MyRecArray^[i].piancha[j])< 0.1) then begin
MObjStd1 := TMeshObject.CreateOwned (GLFreeForm1.MeshObjects);
MObjStd1.Mode := momTriangles;
MObjStd1.Name := 'zcjm'+inttostr(i);
for j := 0 to form1.MyRecArray^[i].pcount-1 do begin
MObjStd1.Vertices.Add (AffineVectorMake (form1.MyRecArray^[i].zuobiao[j,0], form1.MyRecArray^[i].zuobiao[j,1], form1.MyRecArray^[i].jl));
end;
end
else if (abs(form1.MyRecArray^[i].piancha[j])>= 0.1) and (abs(form1.MyRecArray^[i].piancha[j])<1) then begin
MObjStd2 := TMeshObject.CreateOwned (GLFreeForm1.MeshObjects);
MObjStd2.Mode := momTriangles;
MObjStd2.Name := 'zdjm'+inttostr(i);
for j := 0 to form1.MyRecArray^[i].pcount-1 do begin
MObjStd2.Vertices.Add (AffineVectorMake (form1.MyRecArray^[i].zuobiao[j,0], form1.MyRecArray^[i].zuobiao[j,1], form1.MyRecArray^[i].jl));
end;
end
else begin
MObjStd3 := TMeshObject.CreateOwned (GLFreeForm1.MeshObjects);
MObjStd3.Mode := momTriangles;
MObjStd3.Name := 'bcjm'+inttostr(i);
for j := 0 to form1.MyRecArray^[i].pcount-1 do begin
MObjStd3.Vertices.Add (AffineVectorMake (form1.MyRecArray^[i].zuobiao[j,0], form1.MyRecArray^[i].zuobiao[j,1], form1.MyRecArray^[i].jl));
end;
end
end;
end;

Thanks！！！！

[sxbug]

Hi

I have Replaced that code with material processing to 'GLFreeForm1.MeshObjects[0].PrepareMaterialLibraryCache(GLMaterialLibrary1)' . But It is only part of the point can be see, and they were irregular. After exporting the OBJ file, the file has some content (just like # OBJ-File exported by GLScene

Mesh 1

v 152.017196655273 90.8466567993164 157
v 152.053604125977 90.9035186767578 157
v 152.097244262695 90.9611663818359 157), But the 3dsmax is still unable to import. How do I deal with this problem? I want to see the shape.

Thanks