OpenLayers 3.0

1. OL3 A unique mapping library

2. Draw early, Draw often

3. So for good rendering quality: vectors redrawn at each frame while interacting and animating at 60 fps!

4. Performance challenge!

5. Now let's look at the techniques we use in the library

6. #1 batching Minimize data processing and manipulation: style calculations geometry simplifications R-tree lookups object creations replay batch during animations/interactions

7. #2 geometry simplification Douglas Peuker (lines) Quantization to maintain topology (polygons) also allows for better rendering qualtity

8. #3 over-simplification Over-simplification and clipping for the parts that are outside the viewport.

9. (complex and large features)

10. #4 No intermediate canvas for vectors Vector geometries are draw to the output canvas directly. avoid composing transparent pixels save memory Consequence: vector layers are very cheap!

11. Feature Hit Detection

12. (hit detection)

13. Hit Detection Canvas doesn't natively support hit detection. Technique used: redraw the entire "scene" in a 1x1 px canvas, and test if there is a color. Advantages: features under others are detectable pixel-perfect detection tolerance for line detection on touch devices

14. WebGL

15. WebGL WebGL is now everywhere even in iOS! (iOS 8) allow to do thing otherwise not possible

OpenLayers 3.0

Technology