From 600753dc0b4333f2ba70c81e9315b4631888f9fb Mon Sep 17 00:00:00 2001
From: Alex Selimov <alex@alexselimov.com>
Date: Mon, 21 Sep 2026 09:37:38 -0400
Subject: [PATCH] Add Mesh translate function

---
 zigsdof/src/stl.zig | 43 +++++++++++++++++++++++++++++++++++++++----
 1 file changed, 39 insertions(+), 4 deletions(-)

diff --git a/zigsdof/src/stl.zig b/zigsdof/src/stl.zig
index a12819d..f7d9489 100644
--- a/zigsdof/src/stl.zig
+++ b/zigsdof/src/stl.zig
@@ -110,6 +110,13 @@ pub fn rotateMeshAroundPoint(mesh: *Mesh, p: vec3.Vec3F64, q: vec3.QuatF64) void
     return;
 }
 
+pub fn translateMesh(mesh: *Mesh, p: vec3.Vec3F64) void {
+    for (mesh.vertices.items) |*vertex| {
+        vertex.* = vec3.vec3Add(vertex.*, p);
+    }
+    return;
+}
+
 test "Verify fixed point conversion works" {
     const vec = vec3.Vec3F64.init(1.0, 2.134, 1010.11);
     const fixed_point = vecToFixedPoint(vec, 2);
@@ -175,9 +182,7 @@ test "Test binary stl is parsed correctly" {
     ));
 }
 
-test "mesh is rotated correctly" {
-    const allocator = std.testing.allocator;
-
+fn createDummyMesh(allocator: std.mem.Allocator) !Mesh {
     var vertices: std.ArrayList(vec3.Vec3F64) = .empty;
     try vertices.appendSlice(allocator, &.{
         vec3.Vec3F64.init(0, 0, 0),
@@ -193,11 +198,16 @@ test "mesh is rotated correctly" {
     var tri_indices: std.ArrayList([3]usize) = .empty;
     try tri_indices.appendSlice(allocator, &.{.{ 0, 1, 2 }});
 
-    var mesh: Mesh = .{
+    return .{
         .vertices = vertices,
         .triangle_normals = triangle_normals,
         .triangle_vertices = tri_indices,
     };
+}
+test "mesh is rotated correctly" {
+    const allocator = std.testing.allocator;
+
+    var mesh = try createDummyMesh(allocator);
     defer mesh.deinit(allocator);
 
     var orig_mesh: Mesh = .{
@@ -229,3 +239,28 @@ test "mesh is rotated correctly" {
         1e-12,
     ));
 }
+
+test "mesh is translated correctly" {
+    const allocator = std.testing.allocator;
+
+    var mesh = try createDummyMesh(allocator);
+    defer mesh.deinit(allocator);
+
+    translateMesh(&mesh, vec3.Vec3F64.init(1, 1, 1));
+
+    try std.testing.expect(vec3.vec3ApproxEq(
+        mesh.vertices.items[0],
+        vec3.Vec3F64.init(1, 1, 1),
+        1e-12,
+    ));
+    try std.testing.expect(vec3.vec3ApproxEq(
+        mesh.vertices.items[1],
+        vec3.Vec3F64.init(1.5, 1 + std.math.sqrt(3.0) / 2.0, 1),
+        1e-12,
+    ));
+    try std.testing.expect(vec3.vec3ApproxEq(
+        mesh.vertices.items[2],
+        vec3.Vec3F64.init(2, 1, 1),
+        1e-12,
+    ));
+}