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revarbat merged 2 commits into from
May 12, 2026
Merged

docs: add style selection guide and visual comparison for vnf_vertex_array (#521) #1967

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docs: add style selection guide and visual comparison for vnf_vertex_…
junhinhow Apr 6, 2026
ccc2334
Revise triangulation examples in vnf.scad
revarbat May 12, 2026
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147 changes: 147 additions & 0 deletions vnf.scad
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Expand Up @@ -55,6 +55,13 @@ EMPTY_VNF = [[],[]]; // The standard empty VNF with no vertices or faces.
// * "convex" — choose the locally convex division
// * "concave" — choose the locally concave division
// * "quad" — makes quadrilateral edges, which may not be coplanar, relying on OpensCAD to decide how to handle them.
// .
// **Choosing a style:** For smooth surfaces like spheres or swept profiles, "default" or "alt" are
// usually fine. Use "min_edge" to avoid long thin triangles on surfaces with varying curvature.
// Use "convex" or "concave" when you need consistent surface bowing direction (e.g. for textures).
// The "quincunx" style doubles the triangle count by adding center vertices—useful for
// heightfield textures that need sub-quad detail, but avoid it for smooth surfaces as the center
// points create saddle artifacts. The "quad" style is fastest but faces may be non-coplanar.
// Degenerate faces are not included in the output, but if this results in unused vertices, those unused vertices do still appear in the output.
// .
// The vertex list *must* be a rectangular array. If rows of points are generated based on a radius and one of
Expand Down Expand Up @@ -129,6 +136,146 @@ EMPTY_VNF = [[],[]]; // The standard empty VNF with no vertices or faces.
// "intersect" = Anchors to the surface of the shape.
// Named Anchors:
// "origin" = Anchor at the origin, oriented UP.
// Example(3D): Triangulating using `style="default"`. Triangulates the same direction for every quad.
// module show_triangulation(fn, style, steps) {
// pts = [for(u=[0:100/steps:100]) [for(v=[0:100/steps:100]) fn(u,v)]];
// vnf = vnf_vertex_array(pts, style=style);
// grid_vnf = vnf_vertex_array(pts, style="quad");
// color("#ccf") vnf_polyhedron(vnf);
// color("#0dd") vnf_wireframe(vnf, width=0.4);
// color("black") vnf_wireframe(grid_vnf, width=0.5);
// txt = str("style = ", style);
// move([50,0,-20]) rot($vpr) color("black")
// text(txt, size=5, halign="center", valign="top");
// }
// fn = function(u,v) [u, v, 16*sin(u*1.8)*-cos(v*1.8)];
// show_triangulation(fn, "default", steps=4);
// Example(3D): Triangulating using `style="alt"`. The opposite triangulation from "default".
// module show_triangulation(fn, style, steps) {
// pts = [for(u=[0:100/steps:100]) [for(v=[0:100/steps:100]) fn(u,v)]];
// vnf = vnf_vertex_array(pts, style=style);
// grid_vnf = vnf_vertex_array(pts, style="quad");
// color("#ccf") vnf_polyhedron(vnf);
// color("#0dd") vnf_wireframe(vnf, width=0.4);
// color("black") vnf_wireframe(grid_vnf, width=0.5);
// txt = str("style = ", style);
// move([50,0,-20]) rot($vpr) color("black")
// text(txt, size=5, halign="center", valign="top");
// }
// fn = function(u,v) [u, v, 16*sin(u*1.8)*-cos(v*1.8)];
// show_triangulation(fn, "alt", steps=4);
// Example(3D): Triangulating using `style="flip1"`. Alternates triangulation direction in a grid.
// module show_triangulation(fn, style, steps) {
// pts = [for(u=[0:100/steps:100]) [for(v=[0:100/steps:100]) fn(u,v)]];
// vnf = vnf_vertex_array(pts, style=style);
// grid_vnf = vnf_vertex_array(pts, style="quad");
// color("#ccf") vnf_polyhedron(vnf);
// color("#0dd") vnf_wireframe(vnf, width=0.4);
// color("black") vnf_wireframe(grid_vnf, width=0.5);
// txt = str("style = ", style);
// move([50,0,-20]) rot($vpr) color("black")
// text(txt, size=5, halign="center", valign="top");
// }
// fn = function(u,v) [u, v, 16*sin(u*1.8)*-cos(v*1.8)];
// show_triangulation(fn, "flip1", steps=4);
// Example(3D): Triangulating using `style="flip2"`. The opposite pattern from "flip1".
// module show_triangulation(fn, style, steps) {
// pts = [for(u=[0:100/steps:100]) [for(v=[0:100/steps:100]) fn(u,v)]];
// vnf = vnf_vertex_array(pts, style=style);
// grid_vnf = vnf_vertex_array(pts, style="quad");
// color("#ccf") vnf_polyhedron(vnf);
// color("#0dd") vnf_wireframe(vnf, width=0.4);
// color("black") vnf_wireframe(grid_vnf, width=0.5);
// txt = str("style = ", style);
// move([50,0,-20]) rot($vpr) color("black")
// text(txt, size=5, halign="center", valign="top");
// }
// fn = function(u,v) [u, v, 16*sin(u*1.8)*-cos(v*1.8)];
// show_triangulation(fn, "flip2", steps=4);
// Example(3D,Med): Triangulating using `style="quad"`. Lets OpenSCAD do its own internal triangulation. This may error out on older OpenSCAD versions.
// module show_triangulation(fn, style, steps) {
// pts = [for(u=[0:100/steps:100]) [for(v=[0:100/steps:100]) fn(u,v)]];
// vnf = vnf_vertex_array(pts, style=style);
// grid_vnf = vnf_vertex_array(pts, style="quad");
// color("#ccf") vnf_polyhedron(vnf);
// color("#0dd") vnf_wireframe(vnf, width=0.4);
// color("black") vnf_wireframe(grid_vnf, width=0.5);
// txt = str("style = ", style);
// move([50,0,-20]) rot($vpr) color("black")
// text(txt, size=5, halign="center", valign="top");
// }
// fn = function(u,v) [u, v, 16*sin(u*1.8)*-cos(v*1.8)];
// show_triangulation(fn, "quad", steps=4);
// Example(3D): Triangulating using `style="quincunx"`. This artificially adds interpolated points, which may or may not be useful.
// module show_triangulation(fn, style, steps) {
// pts = [for(u=[0:100/steps:100]) [for(v=[0:100/steps:100]) fn(u,v)]];
// vnf = vnf_vertex_array(pts, style=style);
// grid_vnf = vnf_vertex_array(pts, style="quad");
// color("#ccf") vnf_polyhedron(vnf);
// color("#0dd") vnf_wireframe(vnf, width=0.4);
// color("black") vnf_wireframe(grid_vnf, width=0.5);
// txt = str("style = ", style);
// move([50,0,-20]) rot($vpr) color("black")
// text(txt, size=5, halign="center", valign="top");
// }
// fn = function(u,v) [u, v, 16*sin(u*1.8)*-cos(v*1.8)];
// show_triangulation(fn, "quincunx", steps=4);
// Example(3D): Triangulating using `style="convex"`. This is useful for raised hill surfaces.
// module show_triangulation(fn, style, steps) {
// pts = [for(u=[0:100/steps:100]) [for(v=[0:100/steps:100]) fn(u,v)]];
// vnf = vnf_vertex_array(pts, style=style);
// grid_vnf = vnf_vertex_array(pts, style="quad");
// color("#ccf") vnf_polyhedron(vnf);
// color("#0dd") vnf_wireframe(vnf, width=0.4);
// color("black") vnf_wireframe(grid_vnf, width=0.5);
// txt = str("style = ", style);
// move([50,0,-20]) rot($vpr) color("black")
// text(txt, size=5, halign="center", valign="top");
// }
// fn = function(u,v) [u, v, 16*sin(u*1.8)*-cos(v*1.8)];
// show_triangulation(fn, "convex", steps=4);
// Example(3D): Triangulating using `style="concave"`. This is useful for dished surfaces.
// module show_triangulation(fn, style, steps) {
// pts = [for(u=[0:100/steps:100]) [for(v=[0:100/steps:100]) fn(u,v)]];
// vnf = vnf_vertex_array(pts, style=style);
// grid_vnf = vnf_vertex_array(pts, style="quad");
// color("#ccf") vnf_polyhedron(vnf);
// color("#0dd") vnf_wireframe(vnf, width=0.4);
// color("black") vnf_wireframe(grid_vnf, width=0.5);
// txt = str("style = ", style);
// move([50,0,-20]) rot($vpr) color("black")
// text(txt, size=5, halign="center", valign="top");
// }
// fn = function(u,v) [u, v, 16*sin(u*1.8)*-cos(v*1.8)];
// show_triangulation(fn, "concave", steps=4);
// Example(3D): Triangulating using `style="min_edge"`. This triangulates in a way that minimizes face edge lengths.
// module show_triangulation(fn, style, steps) {
// pts = [for(u=[0:100/steps:100]) [for(v=[0:100/steps:100]) fn(u,v)]];
// vnf = vnf_vertex_array(pts, style=style);
// grid_vnf = vnf_vertex_array(pts, style="quad");
// color("#ccf") vnf_polyhedron(vnf);
// color("#0dd") vnf_wireframe(vnf, width=0.4);
// color("black") vnf_wireframe(grid_vnf, width=0.5);
// txt = str("style = ", style);
// move([50,0,-20]) rot($vpr) color("black")
// text(txt, size=5, halign="center", valign="top");
// }
// fn = function(u,v) [u, v, 16*sin(u*1.8)*-cos(v*1.8)];
// show_triangulation(fn, "concave", steps=4);
// Example(3D): Triangulating using `style="min_area"`. This triangulates in a way that minimizes face areas.
// module show_triangulation(fn, style, steps) {
// pts = [for(u=[0:100/steps:100]) [for(v=[0:100/steps:100]) fn(u,v)]];
// vnf = vnf_vertex_array(pts, style=style);
// grid_vnf = vnf_vertex_array(pts, style="quad");
// color("#ccf") vnf_polyhedron(vnf);
// color("#0dd") vnf_wireframe(vnf, width=0.4);
// color("black") vnf_wireframe(grid_vnf, width=0.5);
// txt = str("style = ", style);
// move([50,0,-20]) rot($vpr) color("black")
// text(txt, size=5, halign="center", valign="top");
// }
// fn = function(u,v) [u, v, 16*sin(u*1.8)*-cos(v*1.8)];
// show_triangulation(fn, "concave", steps=4);
// Example(3D):
// vnf = vnf_vertex_array(
// points=[
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