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Set the transparency of a whole mesh

Source: R/mesh_utils.R
set_mesh_alpha.Rd

Returns a copy of the mesh in which every vertex (and every face, if per-face colors are used) has the given alpha value. The renderer blends meshes whose colors are not fully opaque automatically, so this is all that is needed to draw a mesh translucently - for example a brain surface at 10 percent opacity for spatial reference.

Usage

set_mesh_alpha(mesh, alpha)

Arguments

mesh

A mesh descriptor list (see as_scimesh_mesh), e.g. as returned by generate_sphere() or read_ply().

alpha

Alpha value in [0, 1]: 0 = fully transparent, 1 = fully opaque.

Value

A mesh descriptor list with the alpha applied.

Details

A mesh without colors gets uniform colors first (its default_color if it has one, light gray otherwise), so the mesh keeps its appearance and only becomes see-through. Use alpha = 0 for completely invisible geometry and alpha = 1 to make a mesh opaque again.

See also

render_mesh, scene

Examples

sphere <- generate_sphere(c(0, 0, 0), 1)
ghost  <- set_mesh_alpha(sphere, 0.2)

# Per-vertex alpha (here: every other vertex transparent) can be set
# directly on the color matrix:
cols <- sphere$colors
cols[, 4] <- rep(c(0, 1), length.out = nrow(cols))
sphere$colors <- cols