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[Plugin] OBJexporter v3.0 20130131

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  • A Offline
    Alienizer
    last edited by 1 Apr 2011, 23:58

    I see what you mean. I did a test on that door, and I can't push/pull inward, skp says it's offset is at zero! If I remove the back face of the door and keep 5 sides, then it export find in yours. I don't know why it will not push/pull, I see no triangulation in skp that would show this 3D rectangle door not being 100% rectangular. If one face wasn't the same size, other faces would be triangulated accordingly in skp, and the hidden geom would show that, but it doesn't!!

    I was wondering, I know little about skp api but I've look at all the api and I was wondering if there was a better way to get the data. For example, I see that you do not use uvhelper. Maybe there is a way to get the normals and tex uv using an api rather than doing it all over? skp diplays it right, so it must be stored somewhere no?

    I'm from Mars and moved to Earth to alienize you. Unfortunately, I became humanized.

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    • T Offline
      TIG Moderator
      last edited by 2 Apr 2011, 11:22

      It doesn't need to have a 'get_uv_helper' method because it gets the UVs directly from the face.mesh using
      f_uvs=(1..mesh.count_points).map{|i|mesh.uv_at(i,1)}###1=front
      which avoids lots of complex 'getting' otherwise...

      Clearly there's something adrift with those bi-folding doors...
      If you edit one and select-all you get 18 entities - the correct number of faces+edges for a cuboid so there's no tiny bits of stray geometry to mess with us...
      If you edit one of them you you'll find that the door 'slab' is not actually a cuboid - it's slightly skewed - faces don't meet quite at right angles, so PushPulling any vertical face 'inwards' is disallowed. To see this just try making a simple skewed cube and try to PushPull a face 'in' - you can't! because it clashes with connected internal geometry; however, it will PushPull 'out' as there's no clash and it makes two new edges and faces, because the extended side faces aren't coplanar with the original they spring from. This in itself shouldn't mess with the faces' mesh/UV mapping - it's weird...
      Also if you edit the door 'slab' so you can see the axes [switch them 'on' and v8 displays the actual component-axes during the edit, rather than the model-axes as in v7] you find it has been made [or at least inserted] 'upside-down' - the Z/blue axes is 'down' not and not 'up' as it ought to be...
      This might also be confusing the issue, but again it shouldn't matter.
      None of these issues ought to matter but it seems that they do πŸ˜•Capture.PNG

      TIG

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      • A Offline
        Alienizer
        last edited by 2 Apr 2011, 17:23

        I should know better not to ask you about the api, you're the expert, and I'm sure you've already taken the best possible route to make your exporter 😳

        About the door, you're right! I didn't catch that. Is it possible that your exporter reverse the order of the triangle's vertex because the Zaxis is down rather than up? say, p1,p2,p3 becomes p3,p2,p1 but the uv's are for p1,p2,p3, and that's why I get the face normal going in rather then out? My raytrace sees the face material just fine, but becuase it shoots a ray inward (bounce off the face normal) it hits no light, and shows real dark. When I manually reverse p3,p2,p1 to p1,p2,p3, then the bouce of the normal is outward and hits a light, and looks fine.

        One suggestion, is it possible to modify your exporter to save the textures all in png rather than mixed jpg, tga etc? no matter what the original was?

        Thanks tig for taking the time, I appreciate it.

        I'm from Mars and moved to Earth to alienize you. Unfortunately, I became humanized.

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        • T Offline
          TIG Moderator
          last edited by 2 Apr 2011, 17:54

          Clever idea about changing the Texture Files' format on export... πŸ˜„

          Here's v1.6 http://forums.sketchucation.com/viewtopic.php?p=294844#p294844
          Option to export all Texture files in PNG format added [after the OBJ save path has been given].
          'Yes' makes all the exported textures into PNG files: note that the processing might then take a second or two longer as these conversions will take a finite amount of time.
          'No' leaves them in their original format [as <v1.6 exports].

          TIG

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          • A Offline
            Alienizer
            last edited by 2 Apr 2011, 19:31

            WOW that was FAST 😍 Thank you, thank you!

            Any thought about the Zaxis and the reverse p1,p2,p3?

            I'm from Mars and moved to Earth to alienize you. Unfortunately, I became humanized.

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            • T Offline
              TIG Moderator
              last edited by 2 Apr 2011, 19:33

              @alienizer said:

              WOW that was FAST 😍 Thank you, thank you!
              Any thought about the Zaxis and the reverse p1,p2,p3?

              That bit was easy - but that other bit is too obscure... because you should be able to have oddly place components and still return correct UVs πŸ˜•

              TIG

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              • A Offline
                Alienizer
                last edited by 2 Apr 2011, 20:09

                @tig said:

                but that other bit is too obscure... because you should be able to have oddly place components and still return correct UVs πŸ˜•

                hmmm, but when the vertex are CC instead of CCW, the ray/triangle intersect report the hit being on the back face rather then the front! Is there a way in the exporter to know which is p1, p2 and p3? and save them in the proper order? SKP must do it right for it to be able to display the back face in blue when viewed in mono.

                I'm from Mars and moved to Earth to alienize you. Unfortunately, I became humanized.

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                • A Offline
                  Alienizer
                  last edited by 3 Apr 2011, 02:04

                  tig, I found the problem. If you can do a test, (use a model with all faces facing the right way), run your raytrace and for every pixels on the screen, if it hits the back face (turn off back face culling) display that pixel in red, otherwise use some other color, material color perhaps. You will see that using skp exporter, they are fine, using yours, some are not. Now, a quick fix I did was to get the normal <-- cross(edge1,edge2) and then, calculate the normal for p1. Do a dot(Normal, NormalAtP1) and if the result is negative, recreate the face as p3,p2,p1 as oppose to p1,p2,p3, and swap 1 and 3 for the UVs as well. Then your raytrace will show the face correctly. I hope I make sense? Pehars that's how other render do it to correct such problem?

                  I'm from Mars and moved to Earth to alienize you. Unfortunately, I became humanized.

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                  • A Offline
                    Alienizer
                    last edited by 8 Apr 2011, 03:55

                    Sorry to be a pest TIG, but have you had a chance to read me posts? πŸ˜•

                    I'm from Mars and moved to Earth to alienize you. Unfortunately, I became humanized.

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                    • T Offline
                      TIG Moderator
                      last edited by 8 Apr 2011, 07:49

                      I have read it, but I am busy on several other things right now. 😞
                      Why don't you poke around in my code [the #500s lines] and see if you can fix it - then you can have joint (c) credit πŸ˜‰

                      TIG

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                      • A Offline
                        Alienizer
                        last edited by 9 Apr 2011, 02:34

                        @tig said:

                        I have read it, but I am busy on several other things right now. 😞
                        Why don't you poke around in my code [the #500s lines] and see if you can fix it - then you can have joint (c) credit πŸ˜‰

                        🀣 If I was as smart as you perhaps I would!

                        I'm from Mars and moved to Earth to alienize you. Unfortunately, I became humanized.

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                        • T Offline
                          TIG Moderator
                          last edited by 9 Apr 2011, 12:52

                          OK I try to make time to look at it next week... πŸ˜’

                          TIG

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                          • A Offline
                            Alienizer
                            last edited by 9 Apr 2011, 15:39

                            @tig said:

                            OK I try to make time to look at it next week... πŸ˜’

                            THANK YOU TIG 😍

                            I'm from Mars and moved to Earth to alienize you. Unfortunately, I became humanized.

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                            • K Offline
                              Kralizek
                              last edited by 10 Apr 2011, 18:38

                              Works great for for me, thanks a lot TIG!

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                              • I Offline
                                Immer
                                last edited by 16 Apr 2011, 00:08

                                Thanks TIG, this is an incredibly useful plugin, the most reliable obj-exporter I've tried.

                                I have one feature request though - could you add an option to export faces with distorted textures using the original texture and just save the "distorted" UV coordinates in the .obj file? As it is now doing something as simple as exporting a spherically-mapped globe can generate hundreds of distorted texture files and a correspondingly complicated .obj file, not exactly ideal for loading into another program.

                                I've modified version 1.1 to normalize the UVQ coordinates before export and it seems to work fine, it would be nice to have access to the more recent features though so I'm sending you the change in hopes that you'll incorporate it into the next version

                                the relevant change was changing the line
                                f_uvs=(1..mesh.count_points).map{|i|mesh.uv_at(i,1)}####1=front
                                to
                                f_uvs=(1..mesh.count_points).map{|i|flattenUVQ(mesh.uv_at(i,1))}####1=front
                                where flattenUVQ is defined as
                                def flattenUVQ(uvq)
                                return Geom::Point3d.new((uvq.x/uvq.z), (uvq.y/uvq.z), 1.0)
                                end

                                Thanks a bunch!

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                                • T Offline
                                  TIG Moderator
                                  last edited by 16 Apr 2011, 16:06

                                  Sketchup's own OBJexporter also makes individual 'distorted' images when a texture has been 'distorted' by UV mapping - simple rotations or scaling shouldn't produce multiple images.
                                  I added the feature to mimic it because otherwise you don't get the correct 'distortion' - I have previously tried the very method you outline in your code snippet but it never gave satisfactory results. The flattenUVQ method is actually in the code 'unused' [until the more recent updates that make distorted images...].
                                  A distorted texture has 4 uvs but a triangulated mesh makes just 3 per facet ??

                                  TIG

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                                  • I Offline
                                    Immer
                                    last edited by 16 Apr 2011, 21:52

                                    Yeah, I had noticed and used the flattenUVQ method provided - I figured it was something you had brought in from someone else's code but didn't use. I didn't see it in the latest version so I thought I'd include it in case you didn't have an archive of older versions.

                                    Don't get me wrong, it's awesome that you've managed to export non-linearly distorted faces accurately, however for many situations a linear approximation is preferable, especially if lots of additional textures or a complicated group layout present problems - like if you intend to use the exported object in a game engine, or want to fine-tune the UV mapping in another program. It may even be what was actually intended: for example UVTools' spherical map apparently uses distorted textures when linear interpolation is the correct method. In fact I'm not sure it's even possible to specify a lineraly distorted face in Sketchup. I've yet to find a way to, for example, squeeze a rectangular texture onto a trapezoid so the edges and center-points line up perfectly, and that's UV mapping 101.

                                    All I'm suggesting is a checkbox on the option screen to choose between the accurate method and the "clean" one, it should just be a matter of changing the logic to

                                    
                                    if "face is distorted"     *AND* "use accurate method"
                                       create accurate texture
                                       export face using accurate texture
                                    else
                                       output face with normalized UVs # normalizing should have no effect on non-distorted faces
                                    
                                    
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                                    • A Offline
                                      Alienizer
                                      last edited by 17 Apr 2011, 01:48

                                      *** BUG REPORT ***

                                      Using this model from the 3D warehouse...

                                      Error 404 (Not Found)!!1

                                      favicon

                                      (sketchup.google.com)

                                      it export just fine, except the last line in the mtl file is "newmtl fueg" and nothing else after. The file is lock for writing, and after closing Sketchup, the reminder is written to the mtl file.

                                      I'm from Mars and moved to Earth to alienize you. Unfortunately, I became humanized.

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                                      • T Offline
                                        TIG Moderator
                                        last edited by 17 Apr 2011, 12:43

                                        It is a 9Mb SKP and makes an OBJ file with 41 million lines of code so taking 5min+ to complete isn't surprising!
                                        It worked fine for me...
                                        The only 'error' was it didn't write '#EOF' into the end of the MTL file but that's just for me so I know it's done all materials [but it had?]

                                        TIG

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                                        • A Offline
                                          Alienizer
                                          last edited by 17 Apr 2011, 15:42

                                          @tig said:

                                          It is a 9Mb SKP and makes an OBJ file with 41 million lines of code so taking 5min+ to complete isn't surprising!
                                          It worked fine for me...
                                          The only 'error' was it di dn't write '#EOF' into the end of the MTL file but that's just for me so I know it's done all materials [but it had?]

                                          I let mine site all night for 9 hours and the last line of the mtl file still was "newmtl fueg", and the exporter stutus said it was done in 66 secs. So I closed Sketchup and that commited the buffer to the mtl file and it was then complete!

                                          I'm from Mars and moved to Earth to alienize you. Unfortunately, I became humanized.

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