Simplify box() face construction

Resolves #1733

Author: xiaodoliu

CHANGELOG.md

@@ -10,6 +10,8 @@ Change Log / Ray Tracing in One Weekend
 
 ### The Next Week
   - Fix    -- Remove premature source line for call to `get_sphere_uv` (#1701)
+  - Change -- Simplify `box()` face construction to use `min` and `max` points directly
+              without recombining coordinates (#1733)
 
 ### The Rest of Your Life
 

books/RayTracingTheNextWeek.html

@@ -3520,12 +3520,12 @@
         auto dy = vec3(0, max.y() - min.y(), 0);
         auto dz = vec3(0, 0, max.z() - min.z());
 
-        sides->add(make_shared<quad>(point3(min.x(), min.y(), max.z()),  dx,  dy, mat)); // front
-        sides->add(make_shared<quad>(point3(max.x(), min.y(), max.z()), -dz,  dy, mat)); // right
-        sides->add(make_shared<quad>(point3(max.x(), min.y(), min.z()), -dx,  dy, mat)); // back
-        sides->add(make_shared<quad>(point3(min.x(), min.y(), min.z()),  dz,  dy, mat)); // left
-        sides->add(make_shared<quad>(point3(min.x(), max.y(), max.z()),  dx, -dz, mat)); // top
-        sides->add(make_shared<quad>(point3(min.x(), min.y(), min.z()),  dx,  dz, mat)); // bottom
+        sides->add(make_shared<quad>(min, dy, dx, mat)); // back
+        sides->add(make_shared<quad>(min, dx, dz, mat)); // bottom
+        sides->add(make_shared<quad>(min, dz, dy, mat)); // left
+        sides->add(make_shared<quad>(max, -dx, -dy, mat)); // front
+        sides->add(make_shared<quad>(max, -dz, -dx, mat)); // top
+        sides->add(make_shared<quad>(max, -dy, -dz, mat)); // right
 
         return sides;
     }

books/acknowledgments.md.html

@@ -72,6 +72,7 @@
   - [Thien Tran](https://github.com/gau-nernst)
   - Vahan Sosoyan
   - [WANG Lei](https://github.com/wlbksy)
+  - [Xiaodong Liu](https://github.com/xiaodoliu)
   - [Yann Herklotz](https://github.com/ymherklotz)
   - [ZeHao Chen](https://github.com/oxine)
 </div>

src/TheNextWeek/quad.h

@@ -103,12 +103,12 @@ inline shared_ptr<hittable_list> box(const point3& a, const point3& b, shared_pt
     auto dy = vec3(0, max.y() - min.y(), 0);
     auto dz = vec3(0, 0, max.z() - min.z());
 
-    sides->add(make_shared<quad>(point3(min.x(), min.y(), max.z()),  dx,  dy, mat)); // front
-    sides->add(make_shared<quad>(point3(max.x(), min.y(), max.z()), -dz,  dy, mat)); // right
-    sides->add(make_shared<quad>(point3(max.x(), min.y(), min.z()), -dx,  dy, mat)); // back
-    sides->add(make_shared<quad>(point3(min.x(), min.y(), min.z()),  dz,  dy, mat)); // left
-    sides->add(make_shared<quad>(point3(min.x(), max.y(), max.z()),  dx, -dz, mat)); // top
-    sides->add(make_shared<quad>(point3(min.x(), min.y(), min.z()),  dx,  dz, mat)); // bottom
+    sides->add(make_shared<quad>(min, dy, dx, mat)); // back
+    sides->add(make_shared<quad>(min, dx, dz, mat)); // bottom
+    sides->add(make_shared<quad>(min, dz, dy, mat)); // left
+    sides->add(make_shared<quad>(max, -dx, -dy, mat)); // front
+    sides->add(make_shared<quad>(max, -dz, -dx, mat)); // top
+    sides->add(make_shared<quad>(max, -dy, -dz, mat)); // right
 
     return sides;
 }

src/TheRestOfYourLife/quad.h

@@ -122,12 +122,12 @@ inline shared_ptr<hittable_list> box(const point3& a, const point3& b, shared_pt
     auto dy = vec3(0, max.y() - min.y(), 0);
     auto dz = vec3(0, 0, max.z() - min.z());
 
-    sides->add(make_shared<quad>(point3(min.x(), min.y(), max.z()),  dx,  dy, mat)); // front
-    sides->add(make_shared<quad>(point3(max.x(), min.y(), max.z()), -dz,  dy, mat)); // right
-    sides->add(make_shared<quad>(point3(max.x(), min.y(), min.z()), -dx,  dy, mat)); // back
-    sides->add(make_shared<quad>(point3(min.x(), min.y(), min.z()),  dz,  dy, mat)); // left
-    sides->add(make_shared<quad>(point3(min.x(), max.y(), max.z()),  dx, -dz, mat)); // top
-    sides->add(make_shared<quad>(point3(min.x(), min.y(), min.z()),  dx,  dz, mat)); // bottom
+    sides->add(make_shared<quad>(min, dy, dx, mat)); // back
+    sides->add(make_shared<quad>(min, dx, dz, mat)); // bottom
+    sides->add(make_shared<quad>(min, dz, dy, mat)); // left
+    sides->add(make_shared<quad>(max, -dx, -dy, mat)); // front
+    sides->add(make_shared<quad>(max, -dz, -dx, mat)); // top
+    sides->add(make_shared<quad>(max, -dy, -dz, mat)); // right
 
     return sides;
 }