Update book for image 1.14 fix

hollasch · hollasch · commit 313f07a30ffc · 2020-05-30T18:24:33.000-07:00
Resolves #559
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -33,6 +33,7 @@ Change Log -- Ray Tracing in One Weekend
   - Fix: Listing 30: Add missing `camera.h` include
   - Fix: Listing 42: Don't need to include `ray.h` when using `rtweekend.h`
   - Fix: Listing 48: Add missing `material.h` include
+  - Fix: Listing 51: `refract()` function was missing `fabs()` on `sqrt()` argument (#559
   - Fix: Listing 61: Include updated `cam` declaration, show context w/highlighting
   - Fix: Listing 62: Highlight rename of `camera::get_ray()` parameters to s, t (#616)
   - Fix: Listing 63: Show reverted scene declarations
diff --git a/books/RayTracingInOneWeekend.html b/books/RayTracingInOneWeekend.html
@@ -2399,7 +2399,7 @@
     vec3 refract(const vec3& uv, const vec3& n, double etai_over_etat) {
         auto cos_theta = dot(-uv, n);
         vec3 r_out_parallel =  etai_over_etat * (uv + cos_theta*n);
-        vec3 r_out_perp = -sqrt(1.0 - r_out_parallel.length_squared()) * n;
+        vec3 r_out_perp = -sqrt(fabs(1.0 - r_out_parallel.length_squared())) * n;
         return r_out_parallel + r_out_perp;
     }
     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Original file line number	Diff line number	Diff line change
`@@ -2399,7 +2399,7 @@`
`2399`	`2399`	`vec3 refract(const vec3& uv, const vec3& n, double etai_over_etat) {`
`2400`	`2400`	`auto cos_theta = dot(-uv, n);`
`2401`	`2401`	`vec3 r_out_parallel = etai_over_etat * (uv + cos_theta*n);`
`2402`		`- vec3 r_out_perp = -sqrt(1.0 - r_out_parallel.length_squared()) * n;`
	`2402`	`+ vec3 r_out_perp = -sqrt(fabs(1.0 - r_out_parallel.length_squared())) * n;`
`2403`	`2403`	`return r_out_parallel + r_out_perp;`
`2404`	`2404`	`}`
`2405`	`2405`	`~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~`