[x3d-public] Problem with inverted polygons/normals

[Roy Walmsley]

Patrick,

Great spot. Thank you.

That also explains the behaviour of my Coin3D viewer. It saves transparent objects to render after opaque objects, and I had it set to sort transparent objects by distance.

All the best,

Roy

-----Original Message-----
From: x3d-public [mailto:x3d-public-bounces at web3d.org] On Behalf Of Patrick Dähne
Sent: 08 November 2017 15:27
To: X3D Graphics public mailing list <x3d-public at web3d.org>
Subject: Re: [x3d-public] Problem with inverted polygons/normals

> Am 07.11.2017 um 16:17 schrieb Don Brutzman <brutzman at nps.edu>:
> 
> Initial draft version of an interesting new model is available at
> 
> 	Shay D Pixel Version 2
> 	http://x3dgraphics.com/examples/X3dForAdvancedModeling/ShayDPixel/ShayDPixelVersion2Index.html
> 
> This version was exported from an .fbx version using Okino Nugraf.  Original at
> 
> 	http://x3dgraphics.com/examples/X3dForAdvancedModeling/ShayDPixel/pixel_v2.fbx
> 
> It looks OK in several players (such as Instant Reality and X3DOM) but polygon ordering appears reversed in X_ITE.  Adjusting the solid field hasn't helped.  Perhaps a normal issue?
> 
> Wondering if anyone else can figure out what is going on here, screenshot attached for clarity.  TIA for all help.


The texture of the model contains an alpha channel. Remove the alpha channel from the texture, and everything looks right.

As soon as the texture file contains an alpha channel, X3D browsers classify shapes with that texture as transparent shapes. Rendering transparent shapes is difficult. Browsers handle transparent shapes differently. Instant Player and X3DOM write transparent objects to the depth buffer. Most other browser don’t. In this special case, the result of Instant Player and X3DOM looks better than result of other browsers, but that is pure coincidence. None of the browsers is wrong or right.

Bye,

Patrick


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