Imported from vamseeachanta/workspace-hub (
.claude/skills/_archive/engineering/cad/gmsh-meshing/geometry-primitives/SKILL.md). Install upstream withnpx skills add vamseeachanta/workspace-hub --skill geometry-primitives. Copyright stays with the author.
Geometry Primitives (+5)
Geometry Primitives
// Points: Point(id) = {x, y, z, mesh_size};
Point(1) = {0, 0, 0, 1.0};
Point(2) = {10, 0, 0, 1.0};
Point(3) = {10, 5, 0, 0.5};
Point(4) = {0, 5, 0, 0.5};
// Lines
Line(1) = {1, 2};
Line(2) = {2, 3};
*See sub-skills for full details.*
## Surface and Volume
```geo
// Surface from curve loops (first = outer boundary, rest = holes)
Plane Surface(1) = {1};
Plane Surface(2) = {2, 3}; // Surface 2 with hole defined by loop 3
// Surface Loop (for volumes)
Surface Loop(1) = {1, 2, 3, 4, 5, 6};
// Volume from surface loops
Volume(1) = {1};Transformations
// Translate (creates copy if Duplicata used)
Translate {dx, dy, dz} { Surface{1}; }
// Rotate: angle in radians
Rotate {{ax, ay, az}, {px, py, pz}, angle} { Surface{1}; }
// Symmetry
Symmetry {a, b, c, d} { Surface{1}; } // plane ax+by+cz+d=0
*See sub-skills for full details.*
## OpenCASCADE Kernel
```geo
// Enable OpenCASCADE kernel (must be first geometry command)
SetFactory("OpenCASCADE");
// Primitives
Box(1) = {x, y, z, dx, dy, dz};
Sphere(2) = {x, y, z, radius};
Cylinder(3) = {x, y, z, dx, dy, dz, radius};
Cone(4) = {x, y, z, dx, dy, dz, r1, r2};
Torus(5) = {x, y, z, r1, r2};
*See sub-skills for full details.*
## Physical Groups
```geo
// Physical groups assign labels for export
Physical Surface("hull") = {1, 2, 3};
Physical Surface("deck") = {4};
Physical Volume("fluid") = {1};
// Numbered groups
Physical Surface(100) = {1, 2, 3};Mesh Control in .geo
// Characteristic length at points
Characteristic Length {1, 2, 3} = 0.5;
// Transfinite curves (structured)
Transfinite Curve {1, 3} = 20; // 20 nodes
Transfinite Curve {2, 4} = 10; // 10 nodes
Transfinite Curve {1} = 20 Using Progression 1.1; // graded
// Transfinite surface
*See sub-skills for full details.*