Internal modeling not visible through semi-transparent texture.

[Rotornut44]

Hello.
I have been building a greenhouse model off and on over the last few days. The model I have designed is a metal frame greenhouse with what is suppose to be a plastic cover over the entire metal frame. (The frame is just a 2D texture) I have added an alpha channel to my single texture sheet to allow for transparency where needed. Although the transparency now seems to be in place, it doesn't seem to be fully transparent as I can't see any of the structures inside.

I have tried playing around with Alpha Test in the MCX material properties. (I was only able to achieve complete transparency with this method, which is what I don't want.) I also cut out a few of the transparent areas on the model and made them their own poly with their own texture. However, I'm running into the exact same issue as before.

All faces are textured and oriented in the correct directions. Any ideas as to what I could be missing?

I have done transparent 2D railings and such before, but this is the first model I have done where I want to see the 3D internals through a transparent texture. I figure it has to be a priority issue, but then again, I figured to separate "window panes" would be the solution to this..

 

[Rotornut44]

This got me thinking.. I have worked with a similar model before. I have a static Super Cub model that I purchased from a model site. I used it for a static model in a scenery and it has some internal modeling. The model isn't set up much different than the greenhouse above. The window is not a separate model part and it only uses a single texture sheet with an alpha channel, exactly as above. Looking through the material properties in MCX, I can't see anything wildly different from the material properties I have set for the greenhouse. Strange..

 

[=rk=]

This is just a guess, but the difference might be the fact that the inside of the windshield of the Cub model is untextured, as compared to the inside pane of the greenhouse model. Am I correct?

 

[Rotornut44]

I didn't think about that, but you are correct. Removing the internal textures from the canopy made some progress, but didn't resolve the issue. I can now see the cement walkway and some of the wood for the beds, but still a lot is missing. Setting the material to Double Sided allows the canopy to be seen through the inside, but it's still invisible in some areas, as seen in photo #2 below.

 

[=rk=]

Ok, there is probably a material configuration that will work, an alpha test level, or something, that I don't know. For me, the way to avoid this condition, is to work with my transparent part and only, ever apply texture to the outer face, using my normal transparency settings and alpha. If I ever accidentally apply a texture to an interior face model part and remove it, it is not adequate, unless I completely delete all instances of that texture from the model and then start over with it. If I do this, transparencies always seem to work the way I intended.

 

[Rotornut44]

From my previous trials, all Alpha Test managed to do was remove the transparent areas entirely. I even tried walking it down with small value changes, but it seems to be either what you see in the photos above, nothing or just the semi-transparent areas gone. As far as the removing the texture part, that's strange.. I originally had the outer texture mirrored to the inside, but repainted it all with the default material. Figured that would be more than adequate..

 

[Rotornut44]

Instead of exporting as a DAE, I tried to export as an OBJ file. This didn't fix the issue by any means, but oddly more of the internal modeling showed up.

I followed your advice and completely removed the texture from Sketchup. I added it and remapped the canopy again. For the internals, I just mapped a color as I didn't want to remap everything and it not work. Exporting as a DAE and taking a look in MCX, the internals now seem to be visible, but I noticed that from some angles, some triangles of the canopy still seem to be masking others.. (The ends are purposely untextured)

Image #1: Everything seems to be visible, as expected.
Image #2: Opposite side from #1, entire opposing side of canopy is invisible.

 

[GaryGB]

Hi Chris:

You might try using "2-sided-Faces", and apply the Sketchup default "Translucent_Glass_Gray" Material to both sides of each Face.

In Sketchup:

* Materials dialog > {Select} tab > Choose: In Model > Click: "Translucent_Glass_Gray"

* Materials dialog > "Translucent_Glass_Gray" >{Edit} tab > Opacity Slider: 40 %


Next, try exporting from Sketchup as a Google Earth *.KMZ file to ensure that you retain "2-sided-Faces"


NOTE: A default Sketchup Export Collada *.DAE Ruby script [Options] checkbox allows this to be turned On / Off; check those settings before Export !


I use the above Sketchup Material to get properly Z-sorted Faces that are transparent when viewed through (2) or more 2-sided Faces; ...a "Quick-and-Dirty" example:

FYI: I have not checked Material Properties for that mapped Sketchup default "Translucent_Glass_Gray" Material in MCX to see if those attributes interact with Alpha.


Hope this helps.

GaryGB

 

[Rotornut44]

After taking some time off from development, I decided to sit down and try to figure this model out today. I'm glad to announce that, although not perfect, I have finally got this model to work to an acceptable level in the sim. To help others, here is the process I went through:

I first created two additional layers in my Sketchup project, making three total. I then split the model up into 3 components, the base (containing the cement slab and garden boxes), the crops and then the canopy. I assigned the crops and canopy to their own layers, with base on the default, layer0. I then exported the model as two separate DAE files. One DAE contained only the canopy and the other contained the entire base, including the crops.

In MCX, I first opened the base and then imported the canopy into the base. Although this method showed the internals in MCX, it caused an issue. In the sim, all of the internals turned semi-transparent when viewed from the outside. An issue I have ran into and solved before. To sum up the fix in the linked thread, all I had to do was open the canopy in MCX first and then import the base into it. In MCX, the model appears to be broken, as the internals are not visible, but it will render correctly in the sim.

The one reason I state that this is an imperfect fix is that when viewed from the outside, the textured green bars on the inner canopy are still semi-transparent, although not really noticeable unless you are really looking at them.

This can be fixed by separating the bars from the glass by making them their own polygons, then exporting just the glass as it's own model. For the moment, I think I'll move on and put some time into the other models I still need to create..

 

[GaryGB]

Looks very good, Chris ...keep up the great work !

GaryGB