ianmackenzie/elm-3d-camera

Camera type for doing 3D rendering in Elm

Hey! 👋

I work as a software developer at Generative, and I maintain several open-source Elm packages including:

• elm-units
• elm-geometry
• elm-3d-scene

I'm interested in:

• 3D geometry
• Computer-aided design (CAD)
• Computer-aided manufacturing (CAM)
• Using those to help address the climate crisis!

You can generally find me (@ianmackenzie) on the Elm Slack; I tend to hang out mostly in the #geometry and #webgl channels.

elm-3d-camera's Issues

Add examples of how to construct screen rectangle for Camera3d.ray

Cover simple case of window at the top left of the screen, as well as more complex case of a scene somewhere within the page (perhaps with scrolling involved).

Possible way to describe the logic: use Rectangle2d.from p1 p2, where p1 has the coordinates that you'd get if you clicked the lower left corner of the rectangle and p2 has the coordinates you'd get if you clicked the upper right corner.

Change viewPlane to return a Plane3d, not a SketchPlane3d

Instead of projecting directly into a SketchPlane3d, projection should really be done using the various toScreenSpace functions so that both perspective and orthographic cameras are handled properly. It would likely be more useful for viewPlane to return a Plane3d with the normal direction equal to viewDirection, to allow for code like

pointDepth =
    point |> Point3d.signedDistanceFrom (Camera3d.viewPlane camera)

which would be useful for checking if a given 3D point is (for example) between a near and a far clip plane.

Add support for generating 3D CSS transforms?

Would be cool to generate CSS transform attributes so that DOM elements (HTML, SVG etc.) can be easily transformed into 3D space based on a given camera and sketch plane.

For z ordering SVG a .toScreenSpaceWithZ returning a tuple may be helpful

Rename OpenSolid.Viewpoint -> OpenSolid.Camera.Viewpoint

More explicit ('a camera viewpoint'), and as a bonus makes it easier to remember what package it is in

Add Camera3d.projectionMatrix

Unless I've misunderstood something, there doesn't seem to be any way to get the projection matrix of a camera. This means while I can use Camera3d to get the model and view matrix, I have to resort to Math.Matrix4.makePerspective from elm-explorations/linear-algebra for the last part.

I think while adding this, it would also make sense to have Camera3d.viewProjectionMatrix and Camera3d.modelViewProjectionMatrix.

Return records instead of Mat4 values?

Might then be able to avoid dependency on linear-algebra

Add Sphere3d.Projection module

Project 3D sphere to 2D circle

Don't store near/far clip plane in Camera3d

Not all uses of Camera3d will care about near/far clip planes (really only WebGL will, most likely), so probably better to construct Camera3d values without them and then pass them separately when calling projectionMatrix etc.