Added support for loading images

src/image.cpp

@@ -0,0 +1,35 @@
+#include "image.h"
+
+#define STB_IMAGE_IMPLEMENTATION
+#define STBI_FAILURE_USERMSG
+#include "stb_image.h"
+
+inline int clamp(int x, int low, int high) {
+    return (x < low) ? low : ((x < high) ? x : high - 1);
+}
+
+Image::Image(const std::string& filename) {
+    load(filename);
+}
+
+Image::~Image() {
+    STBI_FREE(_data);
+}
+
+bool Image::load(const std::string& filename) {
+    auto n = _bytesPerPixel;
+    _data = stbi_load(filename.c_str(), &_width, &_height, &n, _bytesPerPixel);
+    _bytesPerScanline = _width * _bytesPerPixel;
+    return _data != nullptr;
+}
+
+const unsigned char* Image::pixelData(int x, int y) const {
+    // Return the address of the three bytes of the pixel at x,y (or magenta if no data).
+    static unsigned char magenta[] = { 255, 0, 255 };
+    if (_data == nullptr) return magenta;
+
+    x = clamp(x, 0, _width);
+    y = clamp(y, 0, _height);
+
+    return _data + y * _bytesPerScanline + x * _bytesPerPixel;
+}

src/image.h

@@ -0,0 +1,27 @@
+#pragma once
+
+#include <string>
+
+class Image {
+
+private:
+
+    const int _bytesPerPixel = 3;
+    unsigned char* _data;
+    int _width;
+    int _height;
+    int _bytesPerScanline;
+
+public:
+
+    Image():_data(nullptr) {}
+    ~Image();
+    Image(const std::string& filename);
+    bool load(const std::string& filename);
+
+    inline auto width() const { return _width; }
+    inline auto height() const { return _height; }
+
+    const unsigned char* pixelData(int x, int y) const;
+
+};

src/main.cpp

@@ -71,10 +71,24 @@ void twoSpheres() {
     camera.render(scene, "image.ppm");
 }
 
+void earth() {
+    const auto earth_texture = make_shared<ImageTexture>("earthmap.jpg");
+    const auto earth_surface = make_shared<Lambertian>(earth_texture);
+    const auto globe = make_shared<Sphere>(Point(0.0, 0.0, 0.0), 2.0, earth_surface);
+
+    shared_ptr<Scene> scene = make_shared<Scene>();
+    scene->add(globe);
+
+    Camera camera(16.0 / 9.0, 100, 50, 400, 20.0, Vector(0.0, 0.0, 12.0), Vector(0.0, 0.0, 0.0), Vector(0.0, 1.0, 0.0), 0.0, 10.0);
+
+    camera.render(scene, "image.ppm");
+}
+
 int main() {
-    switch (1) {
+    switch (3) {
         case 1: randomSpheres(); break;
         case 2: twoSpheres(); break;
+        case 3: earth(); break;
     }
     return 0;
 }