Canvas instancing

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native Canvas map widget windows without any PUI (legacy GUI) involved, supporting multiple independent instances - good for quick regression testing, but also profiling and benchmarking

Screen shot showing multiple FG1000 instances; we don't currently have any way to set up Canvas MFD such that they can share sc::Element primitives or a whole scene graph between different instances of the same MFD.

Slightly extended Property Browser to show a preview for each Canvas for troubleshooting/debugging purposes, as per [1] .Details at Canvas_MapStructure#The_SymbolCache

Canvas - the FlightGear 2D drawing API
Canvas - Main Page Canvas News - for the latest developments Shiva Alternatives - ongoing work for Core Profile support Canvas FAQs - frequently asked questions Canvas - Getting started Canvas Development (core) Canvas Troubleshooting (core) Canvas Sandbox (core) PUI2Canvas (PUI/XML Parser) Canvas GUI Canvas Widgets Canvas Maps Canvas Snippets
RFC
Canvas Instancing Howto:New Canvas Execution Model Canvas SVG Canvas Popout Windows Canvas Scenery Overlays
Frameworks
Canvas Map API (soon deprecated!) Canvas MapStructure Canvas MapStructure Layers MapStructure Snippets Canvas Radar Canvas Animation Framework (WIP) Canvas Plotting Framework (WIP) Canvas MFD Framework Canvas ND Framework Canvas PFD Framework Canvas MCDU Framework Canvas EFB Framework Canvas Wrappers Canvas Glass Cockpit Efforts
Tutorials
Howto: Canvas Troubleshooting Howto:Adding a canvas to a GUI dialog (PUI!) Howto:Creating a Canvas GUI dialog file (New) Howto:Dynamic Liveries via Canvas (new) Howto:Creating a Canvas GUI Widget Howto:Add a 2D canvas instrument to your aircraft Howto:Parsing 2D Instruments using the Canvas Howto:Creating fullscreen Canvas applications Howto:Use SVG inside a Canvas Howto:Extend the Canvas SVG module Howto:Serializing a Canvas to SVG Howto:Canvas applications as Nasal submodules Howto:Using raster images and nested canvases Canvas HUD Howto:Project 3D to 2D coordinates on desktop canvas
Reference
Canvas Element Group Image Map Path Text Canvas Nasal API MessageBox Layout System Canvas GUI API Canvas draw library Event Handling
Related
Canvas Properties Unifying the 2D rendering backend via canvas Howto:Use a Camera View in an Instrument Howto:Extending Canvas to support rendering 3D models Howto:Extending Canvas to support MathGL
To be ported
Navigation display Map FGCanvas Canvas Nasal/JavaScript Subset
Deprecated by Canvas
Complex Glass Cockpit Avionics
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not sure if we can share the canvas elements across displays, so I've made copies of everything for each display. — Richard

Without some C++ level sharing of instanced elements, large numbers of complex (SVG path) symbols + DATA will be an issue. [...] Tom has mentioned a sprite cache for instancing, that would work great as a solution — James Turner

Is it possible to duplicate a SVG element in Nasal? I'd like to draw a symbol only once in the SVG and then place multiple instances of it on my display. They need to be unique elements, as I'd like to animate them independently. — Gijs

Unfortunately we have no way to share canvas::Elements between canvases - it's possible at the OSG level but not at any higher level that is exposed. So you probably end up just duplicating the paths and so on. — James Turner

There are some things the Canvas / Map layer do which are not very performance-friendly, especially the symbol-caching / texture-atlasing can be managed better — James Turner

I need to have some discussions with Tom about symbol instancing, since the vector symbols I'm doing for waypoints, VORs and so on should ideally be shared. I'll let Tom speak about his ideas for that. — James Turner

I'm thinking about using a separate canvas for each symbol so that every instance of it is just a textured quad. For efficiency reasons it would be good to draw all symbols to a single canvas/texture and put all quads into a single node. So probably I'll add a new element type for putting quads into a single element which are all rendered at once. Maybe we can even use a geometry shader to just copy the positions to the GPU and generate the full quads with the shader. Ideas and suggestions are always welcome — Thomas Geymayer

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