feat: Render unattached sketch vertices as circles

Co-authored-by: aider (gemini/gemini-2.5-pro) <aider@aider.chat>

src/ViewportWidget.cpp

@@ -24,6 +24,18 @@
 #include <QtMath>
 #include <QOpenGLShaderProgram>
 #include <QVector>
+#include <QMap>
+
+struct PntComparator {
+    bool operator()(const gp_Pnt& a, const gp_Pnt& b) const {
+        // A tolerance is needed for floating point comparisons
+        double tol = 1e-9;
+        if (std::abs(a.X() - b.X()) > tol) return a.X() < b.X();
+        if (std::abs(a.Y() - b.Y()) > tol) return a.Y() < b.Y();
+        if (std::abs(a.Z() - b.Z()) > tol) return a.Z() < b.Z();
+        return false; // They are considered equal
+    }
+};
 
 ViewportWidget::ViewportWidget(QWidget *parent)
     : QOpenGLWidget(parent)
@@ -735,7 +747,7 @@ void ViewportWidget::drawSketch(const SketchFeature* sketch)
     glPointSize(5.0f);
 
     QVector<GLfloat> lineVertices;
-    QVector<GLfloat> pointVertices;
+    QMap<gp_Pnt, int, PntComparator> vertexCounts;
 
     for (const auto& obj : sketch->objects()) {
         if (obj->type() == SketchObject::ObjectType::Line) {
@@ -745,8 +757,16 @@ void ViewportWidget::drawSketch(const SketchFeature* sketch)
             lineVertices << start.X() << start.Y() << start.Z();
             lineVertices << end.X() << end.Y() << end.Z();
 
-            pointVertices << start.X() << start.Y() << start.Z();
-            pointVertices << end.X() << end.Y() << end.Z();
+            vertexCounts[start]++;
+            vertexCounts[end]++;
+        }
+    }
+
+    QVector<GLfloat> pointVertices;
+    for (auto it = vertexCounts.constBegin(); it != vertexCounts.constEnd(); ++it) {
+        if (it.value() == 1) {
+            const gp_Pnt& p = it.key();
+            pointVertices << p.X() << p.Y() << p.Z();
         }
     }
 
@@ -758,8 +778,13 @@ void ViewportWidget::drawSketch(const SketchFeature* sketch)
         glDrawArrays(GL_LINES, 0, lineVertices.size() / 3);
     }
     if (!pointVertices.isEmpty()) {
+        glEnable(GL_POINT_SMOOTH);
+        glEnable(GL_BLEND);
+        glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
         m_vbo.allocate(pointVertices.constData(), pointVertices.size() * sizeof(GLfloat));
         glDrawArrays(GL_POINTS, 0, pointVertices.size() / 3);
+        glDisable(GL_BLEND);
+        glDisable(GL_POINT_SMOOTH);
     }
 
     glEnable(GL_DEPTH_TEST);