From 63cee9aa6eb62afb2e8e726d2de16b76935c5f4c Mon Sep 17 00:00:00 2001
From: Nat Lasseter <user@4574.co.uk>
Date: Mon, 24 Jun 2024 16:22:20 +0100
Subject: Refactor camera

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

(limited to 'camera.go')

diff --git a/camera.go b/camera.go
new file mode 100644
index 0000000..e460cc0
--- /dev/null
+++ b/camera.go
@@ -0,0 +1,64 @@
+package main
+
+import (
+  "fmt"
+  "os"
+)
+
+type Camera struct {
+  ImageWidth uint
+  ImageHeight uint
+  Centre Vec3
+  PDU Vec3
+  PDV Vec3
+  Pixel00 Vec3
+}
+
+func NewCamera(w uint, ar float64) (cam Camera) {
+  cam.ImageWidth = w;
+  cam.ImageHeight = uint(float64(cam.ImageWidth) / ar);
+  if cam.ImageHeight < 1 {
+    cam.ImageHeight = 1;
+  }
+
+  focal_length := 1.0;
+  viewport_height := 2.0;
+  viewport_width := viewport_height *
+                       float64(cam.ImageWidth) /
+                       float64(cam.ImageHeight);
+  cam.Centre = Splat(0);
+
+  viewport_u := Vec3{viewport_width, 0, 0};
+  viewport_v := Vec3{0, -viewport_height, 0};
+
+  cam.PDU = viewport_u.Div(Splat(float64(cam.ImageWidth)));
+  cam.PDV = viewport_v.Div(Splat(float64(cam.ImageHeight)));
+
+  viewport_upperleft := cam.Centre.
+                        Sub(Vec3{0, 0, focal_length}).
+                        Sub(viewport_u.Div(Splat(2))).
+                        Sub(viewport_v.Div(Splat(2)));
+  cam.Pixel00 = viewport_upperleft.
+                 Add(cam.PDU.Add(cam.PDV).Div(Splat(2)));
+
+  return;
+}
+
+func (cam Camera) Render(world Hittable) {
+  fmt.Printf("P3\n%d %d\n255\n", cam.ImageWidth, cam.ImageHeight);
+  for row := uint(0); row < cam.ImageHeight; row++ {
+    fmt.Fprintf(os.Stderr,
+                "Scanlines remaining: %3d...",
+                (cam.ImageHeight - row));
+    for col := uint(0); col < cam.ImageWidth; col++ {
+      pixel_centre := cam.Pixel00.
+                      Add(cam.PDU.Mul(Splat(float64(col)))).
+                      Add(cam.PDV.Mul(Splat(float64(row))));
+      ray_direction := pixel_centre.Sub(cam.Centre);
+      ray := Ray{cam.Centre, ray_direction}
+      pixel_colour := ray.Colour(world);
+      fmt.Printf("%s    ", pixel_colour.ToPPM());
+    }
+    fmt.Printf("\n");
+  }
+}
-- 
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