User:Yiming/GSoC2019/LANPR Document

User document for LANPR

This is for the 2019 version of LANPR. The user interface as well as the functionality has changed a lot since last year’s GSoC. Please refer to this document for clarity. LANPR document will reasonably be included into Blender’s main document as well, if it got merged. This page serves a draft befor the review and merge.

Basic concepts

LANPR is a feature line render engine that is useful for producing artistic or industrial styled line renderings of a 3D scene.

LANPR can be used as a standalone engine, which renders the scene directly, or as a GPencil feature line generator for editing/rendering in other engines as well.

Feature line rendering is useful for making comics, stylized animations, doing structural visualizations, and many other production fields as well. LANPR is much faster than Freestyle, and it’s more accurate and versatile than extracting edges using image filtering methods. The SVG workflow in LANPR and GPencil is another addition to potential external usages.

LANPR components

Currently LANPR can be treated as several major components:

  • Computation: This is for generating feature lines and their occlusion info.
  • Rendering: This is for rendering the line results from computation.
  • “Feature Line” modifier: This is for customizing objects and line types that are included into LANPR computation.
  • GPencil converter: This is for generating GPencil Strokes from LANPR to be later used in other engines.
  • SVG converter: Directly export SVG path from LANPR cache.

Although there are many modules, they are mostly for achieving different targets, and a basic set up won’t require too much effort.

As we talked about, LANPR can be used as an standalone engine, so let’s begin with this one.

LANPR as an engine

This part covers the basics of how to use LANPR engine.

QUICK SETUP for rendering your scene using LANPR

Using LANPR engine:

  1. Select "LANPR" engine.
  2. In LANPR panel, Click "Add line layer" to add 1 default line layer. Or you can click "Default" to add 3 default layers for rendering inner structures.
  3. In the viewport, Choose rendering preview mode, lines should pop up.
  4. F12 to render using LANPR engine.

Using LANPR as Grease Pencil generator.

  1. In any other engines, enable "LANPR" checkbox.
  2. Add a grease pencil object as the stroke holder.
  3. Select the collection you want to be rendered (in the outline).
  4. Go to Collection LANPR tab, enable the LANPR configuration, choose target grease pencil object. Enable all line types.
  5. Manually update in LANPR panel or use auto-update to generate strokes. Auto-update now only operate when frame number changes.

Advanced use of LANPR

LANPR has its own strengths and limitations as well. Please refer to this document for detailed info: