Silhouette edges not shown on molecule under transparent surface

[yaohe@…]

The following bug report has been submitted:
Platform:        Darwin-18.7.0-x86_64-i386-64bit
ChimeraX Version: 0.91 (2019-08-30)
Description
Silhouette edges are not shown on molecules behind transparent surfaces.  Reported by Yao He.

Log:
UCSF ChimeraX version: 0.91 (2019-08-30)  
© 2016-2019 Regents of the University of California. All rights reserved.  
How to cite UCSF ChimeraX  

> open /Users/goddard/ucsf/chimerax/src/core/test.cxs format session

opened ChimeraX session  




OpenGL version: 4.1 ATI-2.11.20
OpenGL renderer: AMD Radeon Pro Vega 20 OpenGL Engine
OpenGL vendor: ATI Technologies Inc.

[Tom Goddard]

Begin forwarded message:

From: YAO HE
Subject: [chimerax-users] silhouette of transparent density
Date: August 30, 2019 at 12:21:05 AM PDT
To: chimerax-users@…

Hi,

I am using ChimeraX now to show the overlay between atomic model and transparent EM densities. However, when I enable the silhouette feature, only the transparent EM densities are affected. I am wondering if it is possible to also silhouette the atomic model inside. Just like "setattr M silhouette true #3" in Chimera.

Best,
Yao

[Tom Goddard]

Chimera on left, ChimeraX on right.

[Tom Goddard]

Fixed.

ChimeraX is not showing silhouette edges on molecules behind transparent surfaces. This is because ChimeraX silhouette edges are drawn where the depth of the scene makes a jump. The depth at a pixel is the depth of the front-most object, so the transparent surface causes ChimeraX not to see the depth of the molecule, hence no silhouette edge on the molecule.

I added some code that separately draws the silhouette edges for opaque models and transparent models, so in tonight’s ChimeraX daily build it will draw silhouettes on molecules under transparent surfaces.