solvespace · phkahler · Dec 10, 2024 · Jan 4, 2025 · Mar 8, 2025
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
@@ -165,6 +165,7 @@ add_library(solvespace-core STATIC
     render/render.cpp
     render/render2d.cpp
     srf/boolean.cpp
+    srf/chamfer.cpp
     srf/curve.cpp
     srf/merge.cpp
     srf/ratpoly.cpp

diff --git a/src/groupmesh.cpp b/src/groupmesh.cpp
@@ -407,6 +407,9 @@ void Group::GenerateShellAndMesh() {
         if(srcg->meshCombine != CombineAs::ASSEMBLE) {
             runningShell.MergeCoincidentSurfaces();
         }
+
+        // Apply any edge modifiers - chamfer / fillet
+        runningShell.ModifyEdges();
 
         // If the Boolean failed, then we should note that in the text screen
         // for this group.

diff --git a/src/srf/chamfer.cpp b/src/srf/chamfer.cpp
@@ -0,0 +1,112 @@
+//-----------------------------------------------------------------------------
+// Algorithm for adding fillets and chamfers to an existing NURBS shell
+// To create these features, edges are split into 2 new edges joined by
+// a new surface which can be flat (chamfer) or round (fillet).
+// Old: surfA, edge, surfB
+// New: surfA, edge1, surfC, edge2, surfB
+//
+// Copyright 2024 Paul H Kahler.
+//-----------------------------------------------------------------------------
+#include "../solvespace.h"
+
+typedef struct {
+    hSCurve     hc;   // handle of the original curve
+    hSSurface   hs;   // handle of the new surface
+
+} fillet_info;
+
+
+// We return 0 for no feature, radius for a fillet, and for chamfers a negative
+// value whose absolute value is the radius of an equivalent fillet.
+double SShell::GetEdgeModifier(SCurve &sc)
+{
+  // for testing we will hard code stuff like returning a radius for only degree 2 curves.
+  // once things work we'll topo-name curves with entity handles and use that to get info.
+  if (!sc.isExact) return 0.0;
+  // chamfer any curve up high
+  if ((sc.exact.deg > 1) && (sc.exact.ctrl[0].z > 9.0)) return -5.0;
+
+  return 0.0;
+}
+
+void SShell::ModifyEdges()
+{
+    dbp("checking edges");
+    // Loop over all curves and create an info struct for the ones to modify
+    // we will call GetEdgeModifier() to get a radius or 0.
+    for(int i=0; i<curve.n; i++) {
+        SCurve *sc = &curve[i];
+        double m = GetEdgeModifier(*sc);
+        bool chamfer = false;
+
+        if (abs(m) > 0.000001)
+        {
+            dbp("modify an edge");
+            if (m < 0.0) {
+                chamfer = true;
+                m = -m;
+            }
+
+
+	// create a new surface C, for the fillet or chamfer
+	// - for now this surface has zero area because the trims are identical
+            SSurface srfC = {};
+            srfC.degm = sc->exact.deg;
+            if (chamfer)
+              srfC.degn = 1;
+            else
+              srfC.degn = 2;
+
+            srfC.degn = 3;  // we're doing something else for now
+
+//            srf.color = ???? what to put here;
+            hSSurface hsrfC = surface.AddAndAssignId(&srfC);
+
+
+        // create 2 new curves/trims as copies of the original. Tag the original curve.
+        // for trims we can just modify existing and add a new one.
+            Vector zeroVec = {0.0, 0.0, 0.0};
+            // create curve A joining surface A with surface C
+            SCurve curveA = {};
+            curveA.isExact = true;
+            curveA.exact = sc->exact.TransformedBy(zeroVec, Quaternion::IDENTITY, 1.0);
+            // copy would be better, but we need to redo this later anyway.
+            (curveA.exact).MakePwlInto(&(curveA.pts));
+            // one of these needs to be the new surface
+            curveA.surfA = sc->surfA;
+            curveA.surfB = hsrfC;
+            hSCurve hcurveA = curve.AddAndAssignId(&curveA);
+
+            // create curve B joining surface B with surface C
+            SCurve curveB = {};
+            curveB.isExact = true;
+            curveB.exact = sc->exact.TransformedBy(zeroVec, Quaternion::IDENTITY, 1.0);
+            // copy would be better, but we need to redo this later anyway.
+            (curveB.exact).MakePwlInto(&(curveB.pts));
+            // one of these needs to be the new surface
+            curveB.surfA = hsrfC;
+            curveB.surfB = sc->surfB;
+            hSCurve hcurveB = curve.AddAndAssignId(&curveB);
+
+
+        }
+    }
+	// Delete the original curves (we can probably leave the curve and modify the trim(s))
+
+	// For each new curve, find the one that matches our start and end point and
+	// shares surfA or B. these are either original unmodified curves or new feature curves
+	// either works, as this is what our new curve will intersect
+
+
+	// Offset all the new curves within their A or B surface
+
+	// Find the intersection points of all our new curves and their neighbors (start and end)
+
+	// Reparameterize our curves and extend our surface if needed (or can U,V go past [0,1]?)
+
+	// Create new trim curves at the ends of our new surface where it meets the others
+	// when we get to corners with 3 fillets we will need a spherical surface to join (hard).
+
+	// Delete our info structures
+}
+
diff --git a/src/srf/surface.h b/src/srf/surface.h
@@ -402,7 +402,9 @@ class SShell {
                                  SEdgeList *el, SShell *useCurvesFrom);
     void RewriteSurfaceHandlesForCurves(SShell *a, SShell *b);
     void CleanupAfterBoolean();
-
+    double GetEdgeModifier(SCurve &sc);
+    void ModifyEdges();
+
     // Definitions when classifying regions of a surface; it is either inside,
     // outside, or coincident (with parallel or antiparallel normal) with a
     // shell.