Merge pull request #897 from mu-lambda/dev-major

Fix scaling in the final Perlin noise texture.

Author: hollasch

CHANGELOG.md

@@ -34,6 +34,7 @@ Change Log -- Ray Tracing in One Weekend
   - Change: Broad rewrite of time management for moving objects, primarily `camera` and
     `moving_sphere`, but also impacting the API for `hittable::bounding_box()` (#799)
   - Fix: Fixed `bvh_node` constructor definition signature (#872)
+  - Fix: Fixed scaling for final Perlin noise texture (#896). 
 
 ### The Rest of Your Life
   - Fix: Added missing functionality for `isotropic` (#664)

books/RayTracingTheNextWeek.html

@@ -2195,7 +2195,8 @@
 
         color value(double u, double v, const point3& p) const override {
     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ C++ highlight
-            return color(1,1,1) * noise.turb(scale * p);
+            auto s = scale * p;
+            return color(1,1,1) * noise.turb(s);
     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ C++
         }
 
@@ -2232,7 +2233,8 @@
 
         color value(double u, double v, const point3& p) const override {
     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ C++ highlight
-            return color(1,1,1) * 0.5 * (1 + sin(scale*p.z() + 10*noise.turb(p)));
+            auto s = scale * p;
+            return color(1,1,1) * 0.5 * (1 + sin(s.z() + 10*noise.turb(s)));
     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ C++
         }
 

books/acknowledgments.md.html

@@ -32,6 +32,7 @@
   - Dan Drummond
   - [David Chambers](https://github.com/dafhi)
   - David Hart
+  - [Dmitry Lomov](https://github.com/mu-lambda)
   - [Eric Haines](https://github.com/erich666)
   - Fabio Sancinetti
   - Filipe Scur

src/common/texture.h

@@ -78,7 +78,8 @@ class noise_texture : public texture {
     noise_texture(double sc) : scale(sc) {}
 
     color value(double u, double v, const point3& p) const override {
-        return color(1,1,1)*0.5*(1 + sin(scale*p.z() + 10*noise.turb(p)));
+        auto s = scale * p;
+        return color(1,1,1)*0.5*(1 + sin(s.z() + 10*noise.turb(s)));
     }
 
   public: