Ian Mackenzie

Overcast, sunny and partly overcast, as described in http://silviojemma.com/public/papers/lighting/spherical-harmonic-lighting.pdf. For best results they should probably use something like importance sampling taking both the BRDF and lighting equation into account (heavily...

```elm Scene3d.overlay : (Camera3d -> Drawing2d.Element msg) -> Option msg ``` used as ```elm Scene3d.renderWith [ overlay ] lights camera scene ``` If multiple overlay options are provided, they can...

Or at least line segments; likely use Unreal method

Big and complex topic; could include - Image-based (cubemap) lighting - Specialized hemispherical or similar lighting - Importance sampling vs. texture pre-processing - HDR textures

Many different approaches - research needed to be done on which ones are most easily implementable, most performant, most physically defensible, actually possible using WebGL and Elm's implementation of it,...

Important for realistic soft lighting; likely use the Unreal method

Useful for 2D drawing but also potentially for 3D graphics (create in 2D then place in 3D). Something like: ```elm Triangle2d.arrowhead : { tip : Point2d units coordinates , direction...

e.g. ```elm Frame3d.fromXySketchPlane : SketchPlane3d units coordinates defines1 -> Frame3d units coordinates defines2 ```

Add weighted centroid functions?

1

Something like ```elm Point2d.weightedCentroid : List ( Point2d units coordinates, Quantity Float weightUnits ) -> Maybe (Point2d units coordinates) ``` and similar for `Point3d`.

Component units don't actually need to match frame/sketch plane units since the origin point is not used (only the basis directions, which are unitless). Match the style of `Vector2d.mirrorAcross` which...