Get a column vector of a matrix

src/basics/matrix.cc

@@ -6,6 +6,7 @@
 #include <cstring>
 #include <stdexcept>
 #include <sstream>
+#include <type_traits>
 
 #include "basics/matrix.hh"
 
@@ -187,6 +188,14 @@ Matrix4::operator()(UInt i,
 }
 
 
+Vector4
+Matrix4::Column(const UInt i)
+    const noexcept
+{
+    return Vector4(operator()(i,0), operator()(i,1), operator()(i,2), operator()(i,3));
+}
+
+
 /*
  * charles::basics::Matrix4::CArray --
  */

src/basics/matrix.hh

@@ -47,6 +47,7 @@ struct Matrix4
      */
     Double& operator()(UInt i, UInt j);
     Double  operator()(UInt i, UInt j) const;
+    Vector4 Column(const UInt i) const noexcept;
 
     /** Get the underlying C array */
     const Double *CArray() const;

src/basics/vector.cc

@@ -33,11 +33,22 @@ Vector4::Vector4()
 Vector4::Vector4(Double x,
                  Double y,
                  Double z)
+    : Vector4(x, y, z, 1.0)
+{ }
+
+
+/*
+ * charles::basics::Vector4::Vector4 --
+ */
+Vector4::Vector4(Double x,
+                 Double y,
+                 Double z,
+                 Double w)
 {
     mData[0] = x;
     mData[1] = y;
     mData[2] = z;
-    mData[3] = 1.0;
+    mData[3] = w;
 }
 
 

src/basics/vector.hh

@@ -20,6 +20,7 @@ struct Vector4
 {
     Vector4();
     Vector4(Double x, Double y, Double z);
+    Vector4(Double x, Double y, Double z, Double w);
 
     Vector4 &operator=(const Vector4 &rhs);
 

src/object.cc

@@ -144,7 +144,9 @@ std::ostream&
 operator<<(std::ostream& ost,
            const Object& object)
 {
+    ost << "[";
     object.Write(ost);
+    ost << " translate=" << object.mTranslation.Column(3) << "]";
     return ost;
 }
 

src/object.hh

@@ -60,6 +60,9 @@ protected:
     virtual basics::Vector4 DoNormal(const basics::Vector4& p) const = 0;
 
 private:
+    friend std::ostream& operator<<(std::ostream& ost, const Object& object);
+
+
     /** Convert `ray` to object space from global space. */
     basics::Ray ToObjectSpace(basics::Ray ray) const;