2 files changed, 47 insertions, 16 deletions

diff --git a/src/glsphere.cpp b/src/glsphere.cpp
index 56144f1..77cb7f7 100644
--- a/src/glsphere.cpp
+++ b/src/glsphere.cpp
@@ -3,8 +3,9 @@
 GLSphere::GLSphere(double radius, int stacks, int slices)
     : GLBody(radius)
 {
-    m_stacks = stacks;
-    m_slices = slices;
+    // Force an even number
+    m_stacks = stacks / 2 * 2;
+    m_slices = slices / 2 * 2;
 }
 
 void GLSphere::makeSurface(QVector<GLPoint> *pointContainer,
@@ -17,35 +18,39 @@ void GLSphere::makeSurface(QVector<GLPoint> *pointContainer,
     QVector3D northpol = v_Y;
     QVector3D southpol = -v_Y;
 
-    QVector3D point1;
-    QVector3D point2;
+    QVector<QVector3D> firstPointRow = calculateRow(0);
+
+    QVector<QVector3D> sliceA = firstPointRow;
+    QVector<QVector3D> sliceB;
 
     m_firstPoint = m_points->size();
 
     for (int slice = 1; slice < m_slices; slice += 2)
     {
+        sliceB = calculateRow(slice);
+
         m_points->append(GLPoint(m_radius * northpol, northpol, t0, m_color));
 
-        for (int stack = 1; stack < m_stacks; stack++)
+        for (int i = 0; i < m_stacks - 1; i++)
         {
-            point1 = calculatePoint(2 * M_PI * slice / m_slices, stack * M_PI / m_stacks);
-            m_points->append(GLPoint(m_radius * point1, point1, t0, m_color));
+            m_points->append(GLPoint(m_radius * sliceA[i], sliceA[i],
+                                     t0, m_color));
 
-            point2 = calculatePoint(2 * M_PI * (slice - 1) / m_slices,
-                                    stack * M_PI / m_stacks);
-            m_points->append(GLPoint(m_radius * point2, point2, t0, m_color));
+            m_points->append(GLPoint(m_radius * sliceB[i], sliceB[i],
+                                     t0, m_color));
         }
 
         m_points->append(GLPoint(m_radius * southpol, southpol, t0, m_color));
 
-        for (int stack = m_stacks - 1; stack >= 1; stack--)
+        sliceA = calculateRow(slice + 1);
+
+        for (int i = m_stacks - 2; i >= 0; i--)
         {
-            point1 = calculatePoint(2 * M_PI * slice / m_slices, stack * M_PI / m_stacks);
-            m_points->append(GLPoint(m_radius * point1, point1, t0, m_color));
+            m_points->append(GLPoint(m_radius * sliceA[i], sliceA[i],
+                                     t0, m_color));
 
-            point2 = calculatePoint(2 * M_PI * (slice + 1) / m_slices,
-                                    stack * M_PI / m_stacks);
-            m_points->append(GLPoint(m_radius * point2, point2, t0, m_color));
+            m_points->append(GLPoint(m_radius * sliceB[i], sliceB[i],
+                                     t0, m_color));
         }
 
         m_points->append(GLPoint(m_radius * northpol, northpol, t0, m_color));
@@ -54,6 +59,29 @@ void GLSphere::makeSurface(QVector<GLPoint> *pointContainer,
     m_nextPoint = m_points->size();
 }
 
+QVector<QVector3D> GLSphere::calculateRow(int slice)
+{
+    if(slice == m_stacks)
+    {
+        return firstRow;
+    }
+
+    QVector<QVector3D> longitude;
+
+    for (int stack = 1; stack < m_stacks; stack++)
+    {
+        longitude.append(calculatePoint(2 * M_PI * slice / m_slices,
+                                        stack * M_PI / m_stacks));
+    }
+
+    if (slice == 0)
+    {
+        firstRow = longitude;
+    }
+
+    return longitude;
+}
+
 QVector3D GLSphere::calculatePoint(double sliceRotation, double stackRotation)
 {
     double x = sin(stackRotation) * sin(sliceRotation);
diff --git a/src/glsphere.h b/src/glsphere.h
index 9aae032..f884117 100644
--- a/src/glsphere.h
+++ b/src/glsphere.h
@@ -22,8 +22,11 @@ private:
      */
     QVector3D calculatePoint(double sliceRotation, double stackRotation);
 
+    QVector<QVector3D> calculateRow(int slice);
+
     int m_stacks;
     int m_slices;
+    QVector<QVector3D> firstRow;
 };
 
 #endif // GLSPHERE_H