4.1 IMPORTANT change to AutoSmoothing!

version 4.1 of blender is about to come out and some significant changes have been made to the way that it deals with surface normal smoothing and if you don't know what's going on it can be confusing and so that's what we're going to talk about in this video so I'm in 4.0 let's come in quickly and just recap how 4.0 Works in order to understand what the changes are in 4.1 when it comes to surface normal smoothing I'm going to create a new UV sphere we want to change the resolution let's go something lower like 16 and 12 so that's pretty good by default we have shade flat turned on if we want to come in and shade all of these flat faces to be smooth shaded we select it bring up the context menu and then invoke shade smooth but right below it we have shade Auto smooth and it can be a little bit confusing as to what the difference is so let's just do shade smooth and there out sphere looks nice and smooth it's just a shading trick of sorts when we come into front view I'm going to press the Tab Key to go into edit mode Let's Take a look at what this looks like when we turn on split normals and I've done a whole video on this but I'm just going to do a quick recap when we look at these lines coming out perpendicular to each vertex if we take a look at the edge let's take a a look at these two vertices we've got a line coming out here and a line coming out here and the shading Blends between these two surface normals but if we were to leave edit mode and let's come back over and do flat shading and then when we come back in to edit mode we can see that in fact the normals are split at each vertex and they are perpendicular to the surface so we don't see any smooth shading and that is what split normal show us they show us whether the surface is being shaded or whether they're not being smooth shaded across the surface because of a split normal so let's come back in and do shade smooth and let's alter the polygon structure in order to look at this in a little bit more Nuance let's come back in now in fact I'm going to temporarily again just uh turn off the normal so that we're not really tasked with having to visually parse through those let's come in and Marquee around these polygons and I'm going to deselect that and then reselect it so it becomes the active uh just so that we can scale from that point I have active element as my Pivot Point location so we can press s and then Z and then zero to flatten that and click so now we've got a situation where we've got a much more defined boundary between polygons so in order to produce a visible boundary there we need to leave polygon edit mode and then come in invoke shade Auto smooth where we manually set the angle that we want the shading to break at meaning any angle that exceeds 30° which is the angle between vertex normals then it automatically does not shade those and produces that hard boundary but shade Auto smooth also does something else for us is it allows us to arbitrarily determine Brakes in the shading according to selected edges and that way we can take very shallow angles and make them look sharp so if I select that boundary Loop bring up the context menu and then invoke Mark Sharp then we can see a break in the shading there so the shade Auto smooth Breaks by angle interactively and it also will break these angles that we manually specify but when you come in and just do shade smooth shade smooth does everything regardless of whether they've been manually set as hard edges and regardless of the angle so this is what we want to understand about 4.0 in order to understand what's changing in 4.1 when I come back to shade Auto smooth it allows for these this angle based braking along with manual braking and it's performing this automatically in the background to the mesh and this behavior is happening on both the cage object and if we assign a subdivision surface to it then that automatically jumps down to the subdivided mesh which is what you're going to be rendering with so for instance if I come in and add a subdivision modifier and let's set this to a value of two interactively we can still see a hint of the broken shading there that we've assigned to the mesh but up here it's subdivided across that large angle and we get smooth shading there but if I come in now and I in Edge mode I double click this Edge press the N key and then set the mean crease to one then the subdivision also looks like a hard boundary there so it's actually two things happening in concert that gives us that hard boundary it is the shading that is automatically broken according to that 30° angles and it's a crease subdivision level so let's keep this in the back of our mind because this is where things are changing in 4 .1 so I've now jumped over to 4.1 and let's take a look at this let's actually create the same setup right here we're going to come over to mesh we're going to create a UV sphere and we're going to configure it to be the same so 16 and 12 okay so when we bring up the context menu now we have shade smooth which is the same but now we have shade Smooth by angle so the shade Auto smooth is gone in 4.1 so let's come in and do the same thing that we had done before let's just come in and turn shade smooth on shade smooth basically operates the same it just takes and Smooths all the angles regardless if you have manual sharp edges it ignores those so it's smoothing everything so let's come in take a look at this and let's do basically the same thing that we had done before is take a bunch of these angles I'm going to select that so it's the active elements period key we go to active I'll just so show that here so we can see it and then when we scale we can scale that down and we have the hard boundary and we can see exactly the same thing that we saw in 4.0 now if we come over and we do a shade Smooth by angle and this is what you're going to be tempted to do is just click the replacement for what you had before we come over here now and we specify we get something similar that showing up here but in fact a new Behavior has been invoked when I come in and press tab to go into edit mode we're going to notice something interesting blender has automatically put in broken shading here so it would be the same as if we selected this brought up the context menu and then did Mark Sharp so that is a change in the behavior and so this new shade Smooth by angle function is just marking edges as sharp if they exceed the breaking angle value that's all it's doing it's not doing an automatic interactive calculation of shading once those edges are marked as sharp they remain sharp until you unmark them as sharp or you reinvoke the command after you've modified the mesh however the automatic functionality is in 4.1 but it's been moved to a new feature so if we jump back in and take this Loop here we can Mark Sharp and then it becomes a sharp boundary also so it's no longer autod detecting this angle the algorithm just simply set it as a sharp angle in the same way that we set this as a sharp angle so let's leave edit mode and what I want to tell you is that the first thing is you probably generally want to stay away from this because this new angle is actually going to be marking sharped edges in the mesh and you may not want that to happen they've moved the automatic algorithmic detection of shading brakes via angle to a new modifier so we come over to the add modifier and we have normal here and it says Smooth by angle so we now have a modifier that will perform the same function that shade Auto smooth did in 4.0 so let's do this let's come in and remove these angles that have been marked sharp so we're going to clear sharp and leave edit mode and now all it's done is it's left this in place so if we turn off that modifier then we'd automatically fall back to the default shade smooth function That's the basis of everything so we turn it back on then it detects that break and shading via the via the 30° angle if you have marked sharp edges let's come back in here and Mark this sharp again so we kind come down and Mark Sharp it will automatically detect and maintain those sharp edges although you can choose to ignore those or not the next thing that we want to notice if we come down here to the data object properties we no longer see a normal entry that normal function the entry that was down here is now handled by this modifier now what's really critical to understand is that if you have a subdivision object the mo position of this modifier is really crucial so let's come in now and generate a subdivision modifier let's take this up to two and you're going to note that we see that break in shading there even though we don't actually have a hard Edge or a crease which is what affects the subdivision object we still see that angle right there and we see the angle right there so what's going on those marked sharp edges are being transferred down to the normals of the subdivided mesh and we get a break and shading there so what you need to remember and this is the single most important thing you want to remember from this tutorial is that this new auto shade or Auto smooth modifier needs to sit underneath the subdivision modifier because you want it to affect the highresolution subdivided mesh in 4.0 the shade Auto smooth function was automatically applying itself to the lowest level piece of geometry that was being generated and you didn't have to think about it but now you just want to make sure that this sits underneath any subdivision modifier or any modifier that's generating geometry that you're wanting to have shading applied to that can break the angle according to angle so let's come in now and do what we had done before and take this boundary at the top and let's set its creas to one so the geometry actually produces a corner there since the smoothing modifier down here sits at the level of handling the subdivided geometry it sees that new hard Edge boundary right there and automatically breaks the shading for us so it's it's effectively functioning as the shade Auto smooth behaved in 4.0 so let's take a look at a couple of other quick things if we come down here to object data properties you're going to note if we expand attribute there is a crease edge and a sharp edge attribute and if you want to in one F swoop remove all of these edges that have been made sharp we can see that boundary you can actually just come down here and remove that we could also remove all the crease edges in one Fell Swoop by removing those like that so let's jump back over to 4.0 and bring in a 4.0 model and see what happens when you bring one in here we are back in 4.1 when I select this you can see that we have the single subdivision modifier so let's go ahead and jump over to 4.1 and see how it opens this file so now we're back over in 4.1 and when we look at the modifier stack you can see that automatically this new auto smooth modifier has been added underneath the subdivision modifier the subdivision modifier generate the subdivided geometry hands that off to the auto smooth modifier and that is what is getting Auto smooth now let's see what happens if we put this on top if I drag this up on top you're going to suddenly notice these breaks in shading this is why it's critical for this to be positioned on the bottom if we let's come into a wireframe go into edit mode the 30° Auto smooth is detecting that some of these are pretty large angles and it's automatically breaking the shading and that shading is getting transferred down to the subdivided geometries normals and that is why when modifier up here the auto smooth is on top we see these brakes and shading so moral of the story is just make sure that it sits underneath and then everything is great

Channel: Christopher 3D

Views: 26,679

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Id: KOPehlWDlU4

Length: 14min 3sec (843 seconds)

Published: Mon Mar 18 2024