Retained 3D scenes and snapshots

Keep the scene, choose a view

The retained scene is right-handed and Z-up. Its coordinates and composed transforms remain exact. Realize exposes that exact primitive stream, Project records the camera approximation policy, and Snapshot lowers the projected records to core Graphics.

Runnable RiXRun cell

.Plugin.Load("scene3d"); mesh := .scene3d.Mesh( [[-1,-1,0], [1,-1,0], [0,1,0], [0,0,2]], [[1,2,3], [1,2,4], [2,3,4], [3,1,4]], {= color="#275dad", width=2 } ); camera := .scene3d.PerspectiveCamera([4,4,3], [0,0,1]); scene := .scene3d.Scene([mesh], {= camera=camera }); .scene3d.Snapshot(scene, {= size=[520,360], mode="wireframe" })["value"];

The browser renders the returned core Graphic. The initial mode is deliberately called wireframe: hidden-line removal is not silently approximated.

You can inspect either intermediate contract directly:

Runnable RiXRun cell

realized := .scene3d.Realize(scene); projected := .scene3d.Project(scene); [realized["schema"], projected["approximation"]];

Sample an exact curve and preserve interaction identity

ParametricCurve evaluates a bounded number of exact RiX samples and retains the sampling contract in node metadata. Axes is an ordinary group of labeled Scene3D leaves. Any leaf can carry a stable id; the projected picking map connects it to every visible segment, face, point, or annotation it produced.

OrbitCamera uses the rational Cayley parameter turn, avoiding trigonometric approximation in the retained camera position. Try changing turn to 1/2, -1/3, or .Complex[:infinity] for the projective half-turn.

Runnable RiXRun cell

.Plugin.Load("scene3d"); curve := .scene3d.ParametricCurve( t -> [2*t-1, 2*t^2-1, t], 0:1, {= samples=17, color="#7c3aed", width=3, id="curve", label="exact parabola" } ); axes := .scene3d.Axes({= length=2, id="basis" }); note := .scene3d.Annotation([1,1,1], "t = 1", {= id="endpoint", color="#7c3aed" }); camera := .scene3d.OrbitCamera([0,0,1/2], {= radius=5, height=2, turn=1/3, projection="perspective", fov=48 }); scene := .scene3d.Scene([axes, curve, note], {= camera=camera }); snapshot := .scene3d.Snapshot(scene, {= size=[520,360] }); [snapshot["value"], snapshot["picking"], camera["orbit"]];

The first array item renders as Graphics. The second is portable interaction metadata, while the third is the reusable rix.scene3d.orbit@1 description. Pointer events themselves belong to the browser host rather than the retained scene.

Refine an exact surface within an explicit budget

ParametricSurface begins with one cell and doubles a conforming grid while its exact midpoint-deviation test exceeds tolerance. The sampling record says whether the requested tolerance was met or which bound stopped the work. Interaction values remain data: a browser may interpret them without changing the retained mesh.

Runnable RiXRun cell

.Plugin.Load("scene3d"); surfaceInteraction := .scene3d.Interaction({= events=["hover","select"], cursor="pointer", tooltip="quadratic surface", selection="toggle", payload={= series="quadratic" } }); surface := .scene3d.ParametricSurface( (u,v) -> [2*u-1,2*v-1,u^2+v^2], 0:1, 0:1, {= tolerance=1/16, maxDepth=4, maxCells=256, color="#0f766e", id="surface", label="quadratic surface", interaction=surfaceInteraction } ); labelPolicy := .scene3d.AnnotationPolicy({= offset=[14,-10], leader=1, priority=10, collision="hide-lower-priority", occlusion="fade" }); peak := .scene3d.Annotation([1,1,2], "peak", {= id="peak", policy=labelPolicy, color="#0f766e" }); camera := .scene3d.OrbitCamera([0,0,3/4], {= radius=5, height=2, turn=1/3, projection="orthographic", scale=4 }); scene := .scene3d.Scene([surface,peak], {= camera=camera }); snapshot := .scene3d.Snapshot(scene, {= size=[520,360] }); [snapshot["value"],surface["metadata"]["sampling"],snapshot["picking"]];

The leader and offset lower to core Graphics. Collision and occlusion remain declared policies in the projected record until a renderer implements them.

Add retained lights and request a lit view

Ambient, directional, and point lights remain part of the Scene3D value. The Phase 1 lit snapshot uses deterministic flat Lambert shading and painter's ordering; it does not claim hidden-surface or shadow certification.

Runnable RiXRun cell

.Plugin.Load("scene3d"); mesh := .scene3d.Mesh( [[-1,-1,0], [1,-1,0], [0,1,0]], [[1,2,3]], {= color="#4080c0" } ); scene := .scene3d.Scene([mesh], {= camera=.scene3d.PerspectiveCamera([3,3,2], [0,0,0]), lights=[ .scene3d.AmbientLight("#ffffff", 1/4), .scene3d.DirectionalLight([1,1,-2], {= intensity=3/4 }) ] }); .scene3d.Snapshot(scene, {= size=[360,240], mode="lit" })["value"];

Preserve unknown cells in a bounded volume slice

Runnable RiXRun cell

.Plugin.Load("scene3d"); .Plugin.Load("calculus"); x := .calculus.Variable(:x); y := .calculus.Variable(:y); z := .calculus.Variable(:z); volume := .scene3d.Volume(x^2+y^2+z^2-1,{= x=(-1):1,y=(-1):1,z=(-1):1 },{= maxCells=7 }); section := .scene3d.Slice(volume,:z,0,{= maxCells=7 }); .scene3d.Snapshot(.scene3d.RegionView(section[:region],{= maxVisibleCells=4 }),{= size=[320,240] });

Amber cells remain unresolved, and the gray box covers omitted display cells. The section is exact; these cell boundaries do not reconstruct surface topology.

Rotate and interpolate exact unit quaternions

Runnable RiXRun cell

.Plugin.Load("scene3d"); rotation := .scene3d.QuaternionBlend([1,0,0,0],[0,0,0,1],1/2); line := .scene3d.Polyline([[0,0,0],[1,0,0]],{= id="arm" }); scene := .scene3d.Scene([.scene3d.QuaternionTransform([line],rotation[:quaternion])]); [rotation[:components],.scene3d.Snapshot(scene,{= size=[240,180] })];

The components are [3/5,0,0,4/5] with exact unit norm. This rational Cayley curve is not constant-speed interpolation; an antipodal endpoint is diagnosed.