►Animate
▼V Reference
52 Find a task or a name
53 Modules to require
54 Scenes and sampling
55 Scene states
56 Animation requests
57 Native model details
58 Visuals
59 Geometry
60 Number Lines and Coordinate Decorations
61 Point Markers, Scatter Plots, and Filled Areas
62 Probability and Statistical Diagrams
63 Calculus lessons
64 Colors
65 Slides
66 Slide command-line tools
67 Source Programs and Authored Timelines
68 Interactive Preview and Inspection
69 Preview controls and diagnostics
70 Projects and Final Rendering
71 Project execution and cache details
72 Pict Renderer Protocol
73 3D reference map
74 3D:   Objects, groups, and paths
75 3D:   Cameras and projection
76 3D:   Views inside a Scene
77 3D:   Animating 3D objects
78 3D:   Animating the 3D camera
79 3D:   Cuts, caps, and section measurements
80 3D:   Supplementary surface, section, and annotation bindings
81 3D:   Cuts, sections, and numerical volume
82 3D:   Vectors
83 3D:   Linear maps and rotations
84 3D:   Affine transforms
85 3D:   Bounds, rays, and planes
86 3D:   Spatial maps and homotopies
87 3D:   Materials and lights
88 3D:   Lighting inspection
89 3D:   Shadow descriptors and stable bounds
90 3D:   Finite-light animation
91 3D:   Software finite-light evaluation
92 3D:   Colour space and final output
93 3D:   Relations and geometric annotations
94 3D:   Projected labels
95 3D:   Textured billboards
96 3D:   Spatial curves and vector diagrams
97 3D:   Spatial anchors and label layout
98 3D:   Anchors and projected labels
99 3D:   Parametric surfaces and calculus
100 3D:   Adaptive, trimmed, and implicit surfaces
101 3D:   Constructive solids
102 3D:   Surface constructors and queries
103 3D:   Meshes
104 3D:   Triangle topology
105 3D:   Polygonal faces
106 3D:   Deterministic convex hulls
107 3D:   Polyhedral duals
108 3D:   Schlegel diagrams and polyhedral nets
109 3D:   Conservative mesh correspondence
110 3D:   Topology-safe mesh matching
111 3D:   Checking and repairing mesh orientation
112 3D:   Clipping, sections, and transparency
113 3D:   Prepared spatial ODE trajectories and vector fields
114 3D:   Seeds and streamline sets
115 3D:   Poincare sections and return maps
116 3D:   Equilibria and local linearization
117 3D:   Flow maps and volume change
118 3D:   Drawing and inspecting trajectories
119 3D:   Reading prepared trajectories
120 3D:   Drawing vector fields and particles
121 3D:   Trajectory display
122 3D:   Spatial inspection and exact picking
123 3D:   Retained renderer backends
124 3D:   Compiled geometry and instances
125 3D:   Frame requests and results
126 3D:   Software rendering and statistics
127 3D:   Optional Racket/  Open  GL backend
128 Experimental Derived Visuals
129 Source Package Hygiene
On this page:
camera3d-move-to
camera3d-look-at-to
camera3d-orbit-by
camera3d-roll-to
camera3d-field-of-view-to
camera3d-orthographic-height-to
camera3d-dolly-by
camera3d-fit
camera3d-follow
9.3
Racket
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78 3D: Animating the 3D camera🔗ℹ

3D reference map · First 3D picture

procedure

(camera3d-move-to view-id position) → any/c

  view-id : symbol?
  position : vec3?
Moves a camera to an absolute position, retaining its lens and orientation.

procedure

(camera3d-look-at-to view-id target [#:up up]) → any/c

  view-id : symbol?
  target : vec3?
  up : vec3? = y-axis3
Reorients a camera to look at a world point.

procedure

(camera3d-orbit-by view-id    
  [#:center center    
  #:azimuth azimuth    
  #:elevation elevation]) → any/c
  view-id : symbol?
  center : vec3? = origin3
  azimuth : finite-real? = 0
  elevation : finite-real? = 0
Creates a finite orbit about center. Position follows the exact orbit; at every sampled position, orientation is a normalized quaternion that looks directly at center. This prevents a camera from looking away from its subject midway through a large orbit.

procedure

(camera3d-roll-to view-id angle) → any/c

  view-id : symbol?
  angle : finite-real?
Sets the absolute roll around the current forward direction.

procedure

(camera3d-field-of-view-to view-id    
  field-of-view) → any/c
  view-id : symbol?
  field-of-view : finite-real?
Interpolates a perspective camera’s vertical field of view. It rejects an orthographic camera.

procedure

(camera3d-orthographic-height-to view-id    
  height) → any/c
  view-id : symbol?
  height : positive-real?
Interpolates an orthographic camera’s visible height. It rejects a perspective camera.

procedure

(camera3d-dolly-by view-id distance) → any/c

  view-id : symbol?
  distance : finite-real?
Moves along the clip-start forward axis; positive distance moves forward.

procedure

(camera3d-fit view-id [#:padding padding]) → any/c

  view-id : symbol?
  padding : positive-real? = 11/10
Frames the current spatial bounds conservatively.

procedure

(camera3d-follow view-id path) → any/c

  view-id : symbol?
  path : spatial-path?
Retains the clip-start camera offset from a spatial target path rooted at the same view. It is resolved after local spatial transforms at each sampled time.

All these forms work as leaves of timed, succession, animation-group, and lagged-start. A 3D camera remains separate from the ordinary two-dimensional render camera, so a formula or caption stays fixed while the view’s spatial camera moves.

In interactive preview, an inspection camera is an overlay on the authored camera: drag in a spatial viewport to orbit, shift-drag to pan its target, use the mouse wheel to dolly (or orthographic zoom), and press R to return to the authored view. The override is part of the immutable preview render request—including a subprocess worker request—and is never written into source or the Scene. The Animate menu can reset it or copy an expression/animation scratch form for authoring.

For runnable examples, see "examples/3d/wireframe-cube.rkt", "examples/3d/opaque-cube.rkt", and "examples/3d/depth-test.rkt"; "examples/3d/camera-orbit.rkt" is the canonical motion probe.

Current limitation: opaque mode is a software rasterizer for filled triangles. It has flat, unlit, and smooth shading, depth-aware transparency, spatial relations, projected labels, specular response, and directional/spot shadows. It does not provide general mesh texture mapping or order-independent transparency. Picking is covered by the inspection chapters. An ordinary two-dimensional traversal of a spatial child is rejected: use rooted 3D animation paths or view3d-spatial-*.

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