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Overview

Webrender is an experimental renderer for Servo that aims to draw web content like a modern game engine.

What does this mean?

• Specialized renderer for web content.
  • Not a general purpose vector graphics API.
  • Complex items such as canvas can be rendered on CPU.
  • Make the common case fast.
• Use GPU to do all rasterization where possible.
  • Items not well suited to GPU rasterizing can be drawn on the CPU and cached in textures.
• Draw only what's on screen
  • Aggressively cull items.
  • Redraw each frame (when there is something to be updated - not a constant fps like games!).
  • Cache results (such as vertex buffers, rasterized glyphs) where possible between frames.
  • Take advantage of knowledge of entire scene up front to optimize drawing.
• Batching
  • Group items into small number of draw calls.
  • Necessary for good performance with OpenGL.

Why try this?

• High resolution displays, GPUs likely to scale better than CPUs here.
• GPUs excel at blits, blending.
• Hit common driver paths used in games, encounter fewer driver bugs?
• May be faster for cases that game engines already deal with (animations, transitions, 3d transforms).
• Simplifies parts of layout and rendering in traditional painting model.
  • Layout no longer needs to worry about layerization, as this is an internal implementation detail!