A True Retopology Shader for the Modeling Viewport

An overlay view of the current model over the underlying geometry that doesn’t make vertices, polygons or lines invisible by clipping through the underlying geometry. At the same time backfaces or hidden geometry should actually become faint by distance or depth of the underlying geometry. Similar to the “limit selection to visible” display but geometry that is on the other side of a thick mesh should be barely visible and not selectable so that remeshing the other side of an already retopologized mesh doesn’t become an irritating and scrambled visual mess.

left: clipped geo, hard to make out. right: while looking kind of usable backfaces interfere with front facing geometry, which in this case is not wanted.

In fact there are several option which all come really close but are still not the complete right thing (suggestion from BlenderArtists: “shrinkwrap, x-ray, and the hidden wire option under N-Panel - Shading.”). Really close but hides beackfaces entirely also doesn’t shade front faces translucently so they can be made out faster, more easily.

Retopoflow actually already has a really nice shader implementation but it works only in the dedicated viewport of shaderflow (a paid addon) and thus only with shaderflow’s toolset. Blender’s native modeling tools can’t be accessed in that display.

Ideally only the actively edited object(s) are displayed that way. Shading display: “retopology” so as soon as an object enters edit mode it gets drawn semi transparent above the other ones in the scene.

Here’s another example from Modo (left) and ZBrush (right):

Ideally only the actively edited object(s) are displayed that way. Shading display: “retopology” so as soon as an object enters edit mode it gets drawn semi transparent above the other ones in the scene.

This has also been a discussion on the 2.8 viewport thread at Blenderartists and there has been a lot of agreement: blenderartists.org/t/blender-2-8-viewport-updates/1114082/402

This post I made over there sums up most of the consensus, I think:

From my current point of view I’d think ideally a topo-view should have these attributes:

• the clean topology mesh should be drawn always above the surface of the source mesh. Bo Geometry should be hidden by the source
• the front faces should be shaded semi transparent with a value to make them more or less transparent.
• backfaces should be drawn in wireframe only
• backfaces should have an option to disable drawing them alltogether
• backfaces should have an option to be drawn fainter the farther they are away from front facing source geometry - meaning - the thicker the mesh the more backfaces should be able to fade out. Making this a toggle would be ideal - sometimes you still do want ot see all the backfaces.
• Topology should always self-occlude backfaces so that selecting any important front facing geometry does not interfere ba accidently selecting backfaces, verts, etc.
• topology shading should be a toggle for the viewport NOT for individual meshes:
  • either topology shading should apply to all currently selected meshes until a new mesh is selected.
  • or optionally meshes could be tagged as “topology” so that they always display semitransparent if “topoview” is active in the viewport. This feels like it could cause confusion because meshes have to be checked for a toggle individually, though.