GSoC/2020/StatusReports/LeonardoEmanuelSegovia

Dynamic Fill Layers in Krita using SeExpr

Abstract

Layers are one of the core concepts of digital painting. They allow artists to control different parts of their artwork at once, for instance, color, lighting, lineart, as well as texture. A key feature of them is their ability to be resized, composited, renamed, grouped or deleted independently of the rest of the document.

Patterns and textures are also essential components of an artist’s toolbox, allowing them to represent the intricacies of a physical material. They come in two forms: bitmap textures, which are images contained in e.g. PNG or OpenEXR files, or procedural textures, which are generated on the fly using their mathematical representation.

KDE’s Krita painting suite supports using patterns and textures through two types of layers, File or Fill Layers. However, neither of them let artists create dynamically generated content: File Layers are inherently static, and Fill Layers support only color fills (like Paint Layers) or basic pattern rendering.

The goal of this project is to let artists create dynamic content through a new, scriptable Fill Layer. To this effect, I integrated Disney Animation’s SeExpr expression language into Krita.

Objectives

There are five parts to this project:

• Add SeExpr as a Fill Layer generator
• Add UI for creation and editing of scripts
• Integrate scripts with the existing Resources system
• Integration tests
• User documentation

In the course of the project, I also addressed:

• Multithread support for Fill Layers
• ARM support for AppImages (including this project's deliverables as well)

Fill Layer generator

WIP: https://phabricator.kde.org/T13337

Status

• 4.3 branch: awaiting review
• master branch: awaiting review

Links

• Proposal: https://summerofcode.withgoogle.com/projects/#6114015970852864
• Phabricator task: https://phabricator.kde.org/T13097
• SeExpr changes: https://invent.kde.org/lsegovia/seexpr/-/compare/master...amyspark%2FT13097-gsoc2020-seexpr
• Merge requests: !380, !411
• Blog posts: https://www.amyspark.me/blog/category/gsoc/