add vec3 and colour

CMakeLists.txt

@@ -2,5 +2,5 @@ cmake_minimum_required(VERSION 3.10)
 
 project(flark)
 
-add_executable(flark main.cpp)
+add_executable(flark main.cpp vec3.h colour.h)
 

colour.h

@@ -0,0 +1,13 @@
+#pragma once
+
+#include "vec3.h"
+
+#include <iostream>
+
+void writeColour(std::ostream &out, colour pixelColour)
+{
+    // write the translated [0,255] value of each colour component.
+    out << static_cast<int>(255.999 * pixelColour.x()) << ' '
+        << static_cast<int>(255.999 * pixelColour.y()) << ' '
+        << static_cast<int>(255.999 * pixelColour.z()) << '\n';
+}

main.cpp

@@ -1,3 +1,6 @@
+#include "colour.h"
+#include "vec3.h"
+
 #include <iostream>
 
 const int WIDTH = 256;
@@ -14,15 +17,8 @@ int main()
 
         for (int x = 0; x < WIDTH; ++x)
         {
-            double r = double(x) / (WIDTH - 1);
-            double g = double(y) / (HEIGHT - 1);
-            double b = 0.25;
-
-            int ir = static_cast<int>(255.999 * r);
-            int ig = static_cast<int>(255.999 * g);
-            int ib = static_cast<int>(255.999 * b);
-
-            std::cout << ir << ' ' << ig << ' ' << ib << std::endl;
+            colour pixelColour(double(x)/(WIDTH-1), double(y)/(HEIGHT-1), 0.25);
+            writeColour(std::cout, pixelColour);
         }
     }
 

vec3.h

@@ -0,0 +1,113 @@
+#pragma once
+
+#include <cmath>
+#include <iostream>
+
+class vec3
+{
+public:
+    vec3() : e{0,0,0} {}
+    vec3(double e0, double e1, double e2) : e{e0, e1, e2} {}
+
+    double x() const { return e[0]; }
+    double y() const { return e[1]; }
+    double z() const { return e[2]; }
+
+    vec3 operator-() const { return vec3(-e[0], -e[1], -e[2]); }
+    double operator[](int i) const { return e[i]; }
+    double& operator[](int i) { return e[i]; }
+
+    vec3& operator+=(const vec3 &v)
+    {
+        e[0] += v.e[0];
+        e[1] += v.e[1];
+        e[2] += v.e[2];
+        return *this;
+    }
+
+    vec3& operator*=(const double t)
+    {
+        e[0] *= t;
+        e[1] *= t;
+        e[2] *= t;
+        return *this;
+    }
+
+    vec3& operator/=(const double t)
+    {
+        return *this *= 1 / t;
+    }
+
+    double length() const 
+    {
+        return std::sqrt(lengthSquared());
+    }
+
+    double lengthSquared() const
+    {
+        return e[0]*e[0] + e[1]*e[1] + e[2]*e[2];
+    }
+
+public:
+    double e[3];
+};
+
+// type aliases for vec3
+using point3 = vec3; // 3D point
+using colour = vec3; // RGB colour
+
+// utility functions
+
+inline std::ostream& operator<<(std::ostream &out, const vec3 &v) 
+{
+    return out << v.e[0] << ' ' << v.e[1] << ' ' << v.e[2];
+}
+
+inline vec3 operator+(const vec3 &u, const vec3 &v)
+{
+    return vec3(u.e[0] + v.e[0], u.e[1] + v.e[1], u.e[2] + v.e[2]);
+}
+
+inline vec3 operator-(const vec3 &u, const vec3 &v)
+{
+    return vec3(u.e[0] - v.e[0], u.e[1] - v.e[1], u.e[2] - v.e[2]);
+}
+
+inline vec3 operator*(const vec3 &u, const vec3 &v)
+{
+    return vec3(u.e[0] * v.e[0], u.e[1] * v.e[1], u.e[2] * v.e[2]);
+}
+
+inline vec3 operator*(double t, const vec3 &v)
+{
+    return vec3(t * v.e[0], t * v.e[1], t * v.e[2]);
+}
+
+inline vec3 operator*(const vec3 &v, double t)
+{
+    return t * v;
+}
+
+inline vec3 operator/(vec3 v, double t)
+{
+    return (1 / t) * v;
+}
+
+inline double dot(const vec3 &u, const vec3 &v)
+{
+    return u.e[0] * v.e[0]
+         + u.e[1] * v.e[1]
+         + u.e[2] * v.e[2];
+}
+
+inline vec3 cross(const vec3 &u, const vec3 &v)
+{
+    return vec3(u.e[1] * v.e[2] - u.e[2] * v.e[1],
+                u.e[2] * v.e[0] - u.e[0] * v.e[2],
+                u.e[0] * v.e[1] - u.e[1] * v.e[0]);
+}
+
+inline vec3 unitVector(vec3 v)
+{
+    return v / v.length();
+}