Deterministic scalar-first surface rasterization — render_surface

Rasterizes a cortical triangle mesh with a per-pixel z-buffer and barycentric interpolation of the scalar field. Thresholding and palette mapping occur after scalar interpolation at each sample. The backend is a CPU implementation and requires neither OpenGL nor a browser.

Usage

render_surface_rgba(
  geometry,
  vertex_values,
  anatomy_metric = NULL,
  cortex_mask = NULL,
  camera = c("lateral", "medial", "dorsal", "ventral"),
  camera_mode = c("canonical", "presentation"),
  presentation_obliquity = 7,
  width = 1200L,
  height = 750L,
  threshold = 0,
  tail = c("two_sided", "positive", "negative"),
  palette = c("#3B4CC0", "#F7F7F7", "#B40426"),
  limits = NULL,
  overlay_alpha = 0.85,
  alpha_ramp = 0,
  antialias = 2L,
  margin = 0.04,
  medial_wall = c("shade", "mask", "outline"),
  outer_contour = TRUE,
  outer_contour_color = "#595959",
  background = "#FBFBF8",
  return_buffers = FALSE,
  anatomy_style = c("publication", "continuous", "binary"),
  anatomy_midpoint = NULL,
  anatomy_invert = FALSE,
  anatomy_range = c(0.72, 0.9)
)

Arguments

geometry: A [SurfaceGeometry] object.
vertex_values: Numeric value per vertex.
anatomy_metric: Optional numeric anatomy metric per vertex. Values are robustly scaled to [0, 1] and modulate a quiet grey substrate.
cortex_mask: Logical cortex-domain mask per vertex. Overlay color is never painted on triangles touching a masked vertex.
camera: One of `"lateral"`, `"medial"`, `"dorsal"`, or `"ventral"`.
camera_mode: Strict canonical orthographic output or a presentation camera with a small, explicit obliquity.
presentation_obliquity: Obliquity in degrees used only for `camera_mode = "presentation"`.
width, height: Output dimensions in pixels.
threshold: Non-negative absolute scalar threshold.
tail: Threshold tail: two-sided, positive, or negative.
palette: Character vector of at least two colors.
limits: Numeric scalar-color limits.
overlay_alpha: Maximum overlay opacity.
alpha_ramp: Width of the opacity ramp above threshold.
antialias: Integer supersampling factor.
margin: Fractional panel margin.
medial_wall: Whether masked-domain triangles are neutrally shaded, omitted, or independently outlined.
outer_contour: Draw a one-pixel contour only where covered cortex touches background connected to the image exterior. Enclosed holes and depth discontinuities are not treated as outer contour.
outer_contour_color: Contour color.
background: Background color.
return_buffers: Include scalar and depth buffers for diagnostics.
anatomy_style: Underlay mapping: legacy publication shading, centered continuous contrast, or binary folding contrast.
anatomy_midpoint, anatomy_invert: Passed to [normalize_surface_anatomy()].
anatomy_range: Dark and light gray levels in [0, 1].

Value

A `surface_rgba` list with raw RGBA, coverage, and overlay-alpha arrays plus camera and rendering provenance.