From 50d22e2bb7e5f4645db6c6710ea1e1ce5d0884a9 Mon Sep 17 00:00:00 2001
From: paul <40677073+paullee0@users.noreply.github.com>
Date: Mon, 10 Nov 2025 01:59:14 +0800
Subject: [PATCH] [ArchStairs] Fix StringerOverlap with Base at Angle (#25167)

* [ArchStairs] Fix StringerOverlap Base at Angle

Github Issue Discussion
- https://github.com/FreeCAD/FreeCAD/issues/24321#issuecomment-3492459309

"... error when Stringer Overlap is set above certain threshold combined with a non-baseless stair which does not have orthogonal direction - this means that the base line or sketch is rotated to a degree, which is not 0, 90, 180 or 270 degrees."

Further
Fix #24321

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
---
 src/Mod/BIM/ArchStairs.py | 32 ++++++++++++++++++++++++++++----
 1 file changed, 28 insertions(+), 4 deletions(-)

diff --git a/src/Mod/BIM/ArchStairs.py b/src/Mod/BIM/ArchStairs.py
index 1d32f666c0..e64753056e 100644
--- a/src/Mod/BIM/ArchStairs.py
+++ b/src/Mod/BIM/ArchStairs.py
@@ -2003,7 +2003,28 @@ class _Stairs(ArchComponent.Component):
                     .multiply(numOfSteps - 1)
                     .add(Vector(0, 0, -vTreadThickness.Length + stringerOverlap))
                 )
+
+                # Shapes of Stringer at Different Cases
+                #
+                #                     p1
+                #                   ∕│
+                #                  ∕ │
+                #                 /  │
+                #                ∕   │
+                #               /    │
+                #              ∕     │
+                #             /      │        p1a -------┐ p1b
+                #            ∕       │           ∕       │
+                #           ∕        │          ∕        │
+                #          ∕         │         ∕         │ p1c
+                #         /          ∕        /          ∕
+                #        /          /        /          /     p1a __________ p1b
+                #       /          ∕        /          ∕         /          ∕
+                #      /          ∕        /          ∕         /          ∕
+                #     /          ⁄        /          ∕         /          ∕
+
                 p1 = vBase.add(l1).add(h1)
+                # TODO: Why not use vBasedAligned but align again?
                 p1 = self.align(p1, align, vWidth)
                 overlapDiff = (float(hgt) / numOfSteps + vTreadThickness.Length) - stringerOverlap
                 strOverlapMax = (structureThickness / vLength.Length) * hyp
@@ -2014,18 +2035,21 @@ class _Stairs(ArchComponent.Component):
                     lProfile.append(p1.add(Vector(0, 0, -strOverlapMax)))
                 else:
                     if (strOverlapMax + overlapDiff) > 0:  # overlapDiff is -ve
-                        vLenDiffP1b = (vLength.Length / vHeight.Length) * overlapDiff
+                        vLenDiffP1a = (vLength.Length / vHeight.Length) * overlapDiff
                         vLenDiffP1c = (structureThickness / vLength.Length) * hyp
                         p1b = p1.add(Vector(0, 0, overlapDiff))  # overlapDiff is -ve
-                        p1a = p1b.add(Vector(vLenDiffP1b, 0, 0))
+                        v1a = DraftVecUtils.scaleTo(vLength, vLenDiffP1a)
+                        p1a = p1b.add(v1a)
                         p1c = p1.add(Vector(0, 0, -vLenDiffP1c))
                         lProfile.append(p1a)
                         lProfile.append(p1b)
                         lProfile.append(p1c)
                     else:
                         vLenDiffP1a = (vLength.Length / vHeight.Length) * (overlapDiff)
-                        p1a = p1.add(Vector(vLenDiffP1a, 0, overlapDiff))
-                        p1b = p1a.add(Vector(strucHorLen, 0, 0))
+                        v1a = DraftVecUtils.scaleTo(vLength, vLenDiffP1a)
+                        p1a = p1.add(Vector(0, 0, overlapDiff)).add(v1a)
+                        v1b = DraftVecUtils.scaleTo(vLength, strucHorLen)
+                        p1b = p1a.add(v1b)
                         lProfile.append(p1a)
                         lProfile.append(p1b)
                 h3 = lProfile[-1].z - vBase.z