seagull 0.1

2D scene graph based on SVG with OpenGL backend

a 2D scene graph based on SVG with OpenGL backend

Goals & non-goals

Goals:

• 2D scene graph suitable for interactive rendering

• minimal set of dependencies

Non-goals:

• full SVG implementation

• optimized for speed

Features

• pythonic API modeled after SVG spec & semantic

• SVG parsing and serialization

• scale dependent polygonalization

• analytical picking

• sub-pixel strokes rendering enhancement through width and opacity correction

• per-pixel gradients

• two modes text rendering: raster by freetype2 for high quality AA at small sizes, vector otherwise

SVG spec

implemented:

• shapes: path, rect, circle, ellipse, line, polyline, polygon, image

• text: (excluding decoration, text on path)

• structure: group, use (including attributes inheritance)

• painting: solid color, linear and radial gradients (including units, transform, spread, href);

• fill: rule (nonzero, evenodd)

• stroke: cap (butt, round, square), join (miter, round, bevel), miterlimit

• multi-pass rendering: clipping, masking, object opacity

• transforms: translate, rotate, scale, skewX, skewY

eventually:

• tspan

• painting: pattern

• stroke: dash, marker

• filters

never:

• DOM API

Dependencies

• PyOpenGL 3.0.2+ OpenGL python bindings

• Pillow 2+ Python Imaging Library (fork)

• freetype2 font engine

• GNU FreeFont Free UCS Outline Fonts

Optional dependencies

Needed to find fonts, fallbacks on FreeFont otherwise.

on the mac:

• pyobjc-framework-CoreText wrappers for the framework CoreText on Mac OS X

Inspirations

• sauvage by S. Conversy

• SVGL by S. Conversy & J.-D. Fekete