Implements #141 normals

Calculate and visualise smoothed normals. The smoothing could be improved to dynamically adjust the smoothing level.

components/renderers/cpp/src/normals.cu

@@ -62,7 +62,7 @@ __global__ void vis_normals_kernel(ftl::cuda::TextureObject<float4> norm,
     if (l == 0) return;
     n /= l;
 
-    output(x,y) = fabs(dot(ray, n))*7.0f;
+    output(x,y) = (1.0f + dot(ray, n))*3.5f;
 }
 
 void ftl::cuda::normal_visualise(ftl::cuda::TextureObject<float4> &norm,