►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:
billboard-image3d
billboard-image3d?
billboard-style3d
billboard3d
9.3
Racket
  top  contents    up   

95 3D: Textured billboards🔗ℹ

3D reference map · First 3D picture

billboard3d is the depth-tested spatial counterpart to a projected label. It is appropriate for a sprite, image annotation, or marker that must exist in the 3D viewport rather than above it. A billboard image is immutable straight-ARGB data, so it can be sampled by a render worker and uploaded by an OpenGL renderer without retaining a GUI bitmap% or a renderer-local texture in the Scene.

procedure

(billboard-image3d width height argb) → billboard-image3d?

  width : exact-positive-integer?
  height : exact-positive-integer?
  argb : bytes?
Creates an immutable source image. argb contains exactly four bytes per pixel in top-to-bottom straight ARGB order. The constructor copies the bytes.

procedure

(billboard-image3d? value) → boolean?

  value : any/c
Recognizes a billboard image source.

procedure

(billboard-style3d [#:width width 
  #:height height 
  #:size-mode size-mode 
  #:facing facing 
  #:axis axis 
  #:opacity opacity 
  #:depth-mode depth-mode 
  #:depth-bias depth-bias]) 
 → billboard-style3d?
  width : positive? = 32
  height : (or/c #f positive?) = #f
  size-mode : (or/c 'screen 'world) = 'screen
  facing : (or/c 'camera 'axis) = 'camera
  axis : vec3? = y-axis3
  opacity : (real-in 0 1) = 1
  depth-mode : (or/c 'test 'always 'hidden) = 'test
  depth-bias : nonnegative-real? = 1e-5
Creates an immutable billboard policy. In 'screen mode, width and height are output pixels; in 'world mode they are physical plane dimensions. An omitted height preserves image aspect ratio. 'camera uses camera image-plane axes; 'axis keeps axis upright and rotates around it toward the camera. Axis-facing therefore requires world sizing. Depth modes have the same meaning as stroke3d: 'test is normally occluded, 'always is an overlay, and 'hidden paints only behind opaque geometry.

procedure

(billboard3d image    
  position    
  #:id id    
  [#:style style    
  #:transform transform    
  #:opacity opacity]) → spatial-visual?
  image : billboard-image3d?
  position : vec3?
  id : symbol?
  style : billboard-style3d? = (billboard-style3d)
  transform : transform3? = identity-transform3
  opacity : (real-in 0 1) = 1
Creates one immutable spatial billboard. Its child path is stable, its camera-dependent plane is resolved only during frame preparation, and transparent texels do not write scene depth.

The software renderer and the explicit Racket/OpenGL renderer consume the same prepared corners, depth policy, and ARGB source. The executable probe is "examples/3d/textured-billboards.rkt".

Billboard limitations: source images use nearest sampling; a billboard whose world quad crosses the frustum boundary is conservatively omitted rather than clipped; partial alpha does not write depth; and billboards do not yet participate in exact spatial picking or cast/receive shadows. Use projected-label for source-mapped formulas and crisp vector text.

  top  contents    up