I wanted to learn procedural modeling. I first looked at Houdini. The official learning path recommends starting with Houdini Fundations, but progress was slow…
Then I suddenly remembered Sverchok. I checked the docs and it felt more interesting.
Note: this post assumes you already understand some basic concepts of procedural modeling
English: Sverchok: Introduction to geometry
Chinese: 菜鸟学bpy（一）新建网格物体
Sverchok docs first introduce the necessary concepts, then quickly move to examples, using step-by-step cases to deepen understanding.
(I think this is a good tutorial approach. Trying to make readers learn all the basic concepts upfront is too boring.)
Enough talk, here’s the point.
In lesson 2, creating a circle. Maybe due to code changes, some node behavior changed slightly. Most steps were fine, but the step get list length, auto-generate polygon broke.
Following the docs and connecting list range to viewer draw caused an error.
As shown below, creating 4 vertices is fine:
But generating the list and connecting it to faces caused an error:
Looking at the output with a viewer node: the hand-written list outputs [[[0,1,2,3]]], but the generated list outputs [[0,1,2,3]] (one pair of brackets missing):
With viewer text, it’s even clearer: the generated list is split into four:
The fix is to use the list join node and enable wrap. Then the list is merged into one, and connecting it to viewer draw works.
2019/11/09 update
Another fix is to setjoinlevel listsof thelist joinnode to 3. That also packages the four values into one.
One more lesson and I’ll finish the docs examples. After that I might write a note to organize what I learned.
(Kind of strange that Sverchok isn’t that well-known. Animation Nodes seems much more popular.)
2019/11/09 update
Found a crash bug in Blender caused by the Viewer text mk3 node.
If this node has inputs and auto-refresh enabled, trying to delete a Sverchok-generated model can crash Blender.
As shown below, deleting this cube will crash Blender:
Blender version v2.82.1 daily build(11/08)
Sverchok version 0.6.0.0
Issue filed on GitHub: Viewer text mk3 node bug
2019/11/13 update
Uploaded a 4k screen recording to YouTube: Sverchok docs case