Render: Clamp minimum DOF focus distance

Clamp DOF focus distance to a minimum of 1e-5.
This is to primarily stop focus distances of 0 being used
which would lead to issues in future code changes.

Pull Request: https://projects.blender.org/blender/blender/pulls/123310

intern/cycles/scene/camera.cpp

@@ -395,7 +395,7 @@ void Camera::update(Scene *scene)
 
   /* depth of field */
   kcam->aperturesize = aperturesize;
-  kcam->focaldistance = focaldistance;
+  kcam->focaldistance = max(focaldistance, 1e-5f);
   kcam->blades = (blades < 3) ? 0.0f : blades;
   kcam->bladesrotation = bladesrotation;
 

source/blender/blenkernel/intern/camera.cc

@@ -290,9 +290,9 @@ float BKE_camera_object_dof_distance(const Object *ob)
                   ob->object_to_world().location(),
                   cam->dof.focus_object->object_to_world().location());
     }
-    return fabsf(dot_v3v3(view_dir, dof_dir));
+    return fmax(fabsf(dot_v3v3(view_dir, dof_dir)), 1e-5f);
   }
-  return cam->dof.focus_distance;
+  return fmax(cam->dof.focus_distance, 1e-5f);
 }
 
 float BKE_camera_sensor_size(int sensor_fit, float sensor_x, float sensor_y)