How a geometry's vertices assemble into primitives.
The MVP tier (§120) draws filled shapes and debug/wire lines, so the two
modes are "triangles" and "lines"; strips, fans, and points are not
exposed because nothing in this phase emits them (a fan is expanded into
indexed triangles by circleGeometry2D instead — see primitives.ts).
The mode fixes how many indices — or, unindexed, how many vertices — make one
primitive: three for "triangles", two for "lines".
How a geometry's vertices assemble into primitives.
The MVP tier (§120) draws filled shapes and debug/wire lines, so the two modes are
"triangles"and"lines"; strips, fans, and points are not exposed because nothing in this phase emits them (a fan is expanded into indexed triangles by circleGeometry2D instead — seeprimitives.ts). The mode fixes how many indices — or, unindexed, how many vertices — make one primitive: three for"triangles", two for"lines".