From b7814d6822d03517fc846b95865965618be7d406 Mon Sep 17 00:00:00 2001
From: Nat Lasseter <user@4574.co.uk>
Date: Mon, 24 Jun 2024 16:01:18 +0100
Subject: Initial Commit, finished Chapter 6

---
 rtiaw.go | 64 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 64 insertions(+)
 create mode 100644 rtiaw.go

(limited to 'rtiaw.go')

diff --git a/rtiaw.go b/rtiaw.go
new file mode 100644
index 0000000..9f900b6
--- /dev/null
+++ b/rtiaw.go
@@ -0,0 +1,64 @@
+package main
+
+import (
+	"fmt"
+  "os"
+  "time"
+)
+
+func main() {
+  start := time.Now();
+
+  image_width := 400;
+  aspect := 16.0 / 9.0;
+
+  var world Hittables;
+  world.Add(Sphere{Vec3{0,    0  , -1},   0.5});
+  world.Add(Sphere{Vec3{0, -100.5, -1}, 100  });
+
+  image_height := int(float64(image_width) / aspect);
+  if image_height < 1 {
+    image_height = 1;
+  }
+
+  focal_length := 1.0;
+  viewport_height := 2.0;
+  viewport_width := viewport_height *
+                      (float64(image_width) / float64(image_height));
+  camera_centre := Splat(0);
+
+  viewport_u := Vec3{viewport_width, 0, 0};
+  viewport_v := Vec3{0, -viewport_height, 0};
+
+  pd_u := viewport_u.Div(Splat(float64(image_width)));
+  pd_v := viewport_v.Div(Splat(float64(image_height)));
+
+  viewport_upperleft := camera_centre.
+                        Sub(Vec3{0, 0, focal_length}).
+                        Sub(viewport_u.Div(Splat(2))).
+                        Sub(viewport_v.Div(Splat(2)));
+  pixel00_loc := viewport_upperleft.
+                 Add(pd_u.Add(pd_v).Div(Splat(2)));
+
+  fmt.Printf("P3\n%d %d\n255\n", image_width, image_height);
+  for row := 0; row < image_height; row++ {
+    fmt.Fprintf(os.Stderr,
+                "Scanlines remaining: %3d...",
+                (image_height - row));
+    for col := 0; col < image_width; col++ {
+      pixel_centre := pixel00_loc.
+                      Add(pd_u.Mul(Splat(float64(col)))).
+                      Add(pd_v.Mul(Splat(float64(row))));
+      ray_direction := pixel_centre.Sub(camera_centre);
+      ray := Ray{camera_centre, ray_direction}
+      pixel_colour := ray.Colour(world);
+      fmt.Printf("%s    ", pixel_colour.ToPPM());
+    }
+    fmt.Printf("\n");
+  }
+
+  dur := time.Since(start);
+  fmt.Fprintf(os.Stderr,
+              "Done, in %5.2f seconds!    \n",
+              dur.Seconds());
+}
-- 
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