From b8bdd91e40bde0fddc734575a9b83f9a4dcf5a9a Mon Sep 17 00:00:00 2001
From: Armin Friedl <dev@friedl.net>
Date: Sat, 30 Jul 2022 20:50:18 +0200
Subject: [PATCH] Camera view geometry

---
 rtiww/src/camera.h | 40 +++++++++++++++++++++-------------------
 rtiww/src/main.cpp |  3 ++-
 2 files changed, 23 insertions(+), 20 deletions(-)

diff --git a/rtiww/src/camera.h b/rtiww/src/camera.h
index 4e5f049..e70212f 100644
--- a/rtiww/src/camera.h
+++ b/rtiww/src/camera.h
@@ -5,29 +5,31 @@
 
 class camera {
 public:
-  camera() {
-    auto aspect_ratio = 16.0 / 9.0;
-    auto viewport_height = 2.0;
-    auto viewport_width = aspect_ratio * viewport_height;
-    auto focal_length = 1.0;
+    camera(double vfov /*vertical field-of-view in degrees*/, double aspect_ratio) {
 
-    origin = point3(0, 0, 0);
-    horizontal = vec3(viewport_width, 0.0, 0.0);
-    vertical = vec3(0.0, viewport_height, 0.0);
-    lower_left_corner =
-        origin - horizontal / 2 - vertical / 2 - vec3(0, 0, focal_length);
-  }
+        auto theta = degrees_to_radians(vfov);
+        auto h = tan(theta / 2);
+        auto viewport_height = 2.0 * h;
+        auto viewport_width = aspect_ratio * viewport_height;
+        auto focal_length = 1.0;
 
-  ray get_ray(double u, double v) const {
-    return ray(origin,
-               lower_left_corner + u * horizontal + v * vertical - origin);
-  }
+        origin = point3(0, 0, 0);
+        horizontal = vec3(viewport_width, 0.0, 0.0);
+        vertical = vec3(0.0, viewport_height, 0.0);
+        lower_left_corner =
+                origin - horizontal / 2 - vertical / 2 - vec3(0, 0, focal_length);
+    }
+
+    ray get_ray(double u, double v) const {
+        return ray(origin,
+                   lower_left_corner + u * horizontal + v * vertical - origin);
+    }
 
 private:
-  point3 origin;
-  point3 lower_left_corner;
-  vec3 horizontal;
-  vec3 vertical;
+    point3 origin;
+    point3 lower_left_corner;
+    vec3 horizontal;
+    vec3 vertical;
 };
 
 #endif // CAMERA_H_
diff --git a/rtiww/src/main.cpp b/rtiww/src/main.cpp
index 60e281d..303eb59 100644
--- a/rtiww/src/main.cpp
+++ b/rtiww/src/main.cpp
@@ -54,11 +54,12 @@ int main() {
       make_shared<sphere>(point3(0.0, -100.5, -1.0), 100.0, material_ground));
   world.add(make_shared<sphere>(point3(0.0, 0.0, -1.0), 0.5, material_center));
   world.add(make_shared<sphere>(point3(-1.0, 0.0, -1.0), 0.5, material_left));
+  world.add(make_shared<sphere>(point3(-1.0, 0.0, -1.0), -0.4, material_left));
   world.add(make_shared<sphere>(point3(1.0, 0.0, -1.0), 0.5, material_right));
 
   // Camera
 
-  camera cam;
+  camera cam(90, aspect_ratio);
 
   // Render