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52 Find a task or a name
53 Modules to require
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60 Number Lines and Coordinate Decorations
61 Point Markers, Scatter Plots, and Filled Areas
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74 3D:   Objects, groups, and paths
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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
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96 3D:   Spatial curves and vector diagrams
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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:
clip-plane3d
clip-plane3d?
clip3d
clip3d?
slice-mesh3d
vertex-color-lerp
slice-mesh-by-planes3d
section-by-plane3d
section3d?
section3d-loops
section3d-chains
section-curve3d
9.3
Racket
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112 3D: Clipping, sections, and transparency🔗ℹ

3D reference map · First 3D picture

Render clipping and geometric slicing are distinct operations. clip3d keeps its source subtree intact and clips only the triangles submitted to a view3d renderer. slice-mesh3d instead returns new half-space mesh geometry; it deliberately does not invent a cap. Use section-by-plane3d for the actual plane intersection and section-curve3d to draw every loop or open chain as ordinary spatial curves.

procedure

(clip-plane3d plane [#:keep keep]) → clip-plane3d?

  plane : plane3?
  keep : (or/c 'positive 'negative) = 'positive
Describes the retained half-space of a clipping plane.

procedure

(clip-plane3d? value) → boolean?

  value : any/c
Recognizes a clipping-plane description.

procedure

(clip3d content clip #:id id) → clip3d?

  content : spatial-visual?
  clip : (or/c plane3? clip-plane3d?)
  id : symbol?
Wraps one spatial subtree with local render-only clipping.

procedure

(clip3d? value) → boolean?

  value : any/c
Recognizes a render-clip wrapper.

procedure

(slice-mesh3d mesh clip) → mesh3d?

  mesh : mesh3d?
  clip : (or/c plane3? clip-plane3d?)
Returns actual, deterministically triangulated clipped mesh geometry in the source mesh’s local coordinates. Generated cut vertices reuse one source-edge registry and therefore interpolate the supported per-vertex normal and RGBA colour attributes consistently across neighbouring triangles.

procedure

(vertex-color-lerp first second amount) → color-spec?

  first : color-spec?
  second : color-spec?
  amount : finite-real?
Interpolates one mesh colour attribute in encoded-sRGB components with straight alpha. It is the spatial-attribute convention used by mesh slicing and deliberately differs from color-mix’s default linear-light, premultiplied authoring blend. Tokens remain unresolved until a render context is selected.

procedure

(slice-mesh-by-planes3d mesh clips) → mesh3d?

  mesh : mesh3d?
  clips : (listof (or/c plane3? clip-plane3d?))
Applies plane cuts in declaration order to produce actual geometry. This is not clip-planes3d, which remains render-only.

procedure

(section-by-plane3d mesh clip) → section3d?

  mesh : mesh3d?
  clip : (or/c plane3? clip-plane3d?)
Returns deterministic section3d topology. Its section3d-loops and section3d-chains accessors distinguish closed components from open ones.

procedure

(section3d? value) → boolean?

  value : any/c
Recognizes plane-section topology.

procedure

(section3d-loops section) → (listof (listof vec3?))

  section : section3d?
Returns its closed components in deterministic plane orientation.

procedure

(section3d-chains section) → (listof (listof vec3?))

  section : section3d?
Returns its open components in deterministic endpoint order.

procedure

(section-curve3d mesh clip #:id id) → group3d?

  mesh : mesh3d?
  clip : (or/c plane3? clip-plane3d?)
  id : symbol?
Builds a group of physical-radius tube curves for every section component.

material3d accepts an alpha-bearing semantic colour. In an opaque view3d, fully opaque geometry writes the depth buffer first; transparent geometry is then rendered far-to-near with 'object-sorted or 'triangle-sorted #:transparency-mode. Transparent triangles depth-test against opaque geometry but do not write depth. A projected-label accepts #:occlusion 'always-visible, 'hide, or 'fade; its occlusion test uses that opaque depth target, preserving the label as a crisp 2D Visual.

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