Chapter 8

1 files changed, 23 insertions, 7 deletions

diff --git a/camera.go b/camera.go
index e460cc0..569d385 100644
--- a/camera.go
+++ b/camera.go
@@ -12,15 +12,18 @@ type Camera struct {
   PDU Vec3
   PDV Vec3
   Pixel00 Vec3
+  AntiAliasing uint
 }
 
-func NewCamera(w uint, ar float64) (cam Camera) {
+func NewCamera(w uint, ar float64, aa uint) (cam Camera) {
   cam.ImageWidth = w;
   cam.ImageHeight = uint(float64(cam.ImageWidth) / ar);
   if cam.ImageHeight < 1 {
     cam.ImageHeight = 1;
   }
 
+  cam.AntiAliasing = aa;
+
   focal_length := 1.0;
   viewport_height := 2.0;
   viewport_width := viewport_height *
@@ -51,14 +54,27 @@ func (cam Camera) Render(world Hittable) {
                 "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);
+      pixel_colour := Splat(0);
+      for i := uint(0); i < cam.AntiAliasing; i++ {
+        r := cam.GetRay(row, col);
+        pixel_colour = pixel_colour.Add(r.Colour(world));
+      }
+      pixel_colour = pixel_colour.Div(Splat(float64(cam.AntiAliasing)));
       fmt.Printf("%s    ", pixel_colour.ToPPM());
     }
     fmt.Printf("\n");
   }
 }
+
+func (cam Camera) GetRay(row uint, col uint) Ray {
+  offset := unit_square();
+  pixel_sample := cam.Pixel00.
+                  Add(cam.PDU.Mul(Splat(float64(col) + offset.X))).
+                  Add(cam.PDV.Mul(Splat(float64(row) + offset.Y)));
+  return Ray{cam.Centre, pixel_sample.Sub(cam.Centre)};
+}
+
+func unit_square() Vec3 {
+  i := Interval{-0.5, 0.5};
+  return Vec3{i.Sample(), i.Sample(), 0};
+}