intern/cycles/integrator/render_scheduler.cpp

@@ -128,9 +128,8 @@ void RenderScheduler::reset(const BufferParams &buffer_params, int num_samples,
     state_.resolution_divider = 1;
   }
   else {
-    /* NOTE: Divide by 2 because of the way how scheduling works: it advances resolution divider
-     * first and then initialized render work. */
-    state_.resolution_divider = start_resolution_divider_ * 2;
+    state_.user_is_navigating = true;
+    state_.resolution_divider = start_resolution_divider_;
   }
 
   state_.num_rendered_samples = 0;
@@ -312,7 +311,21 @@ RenderWork RenderScheduler::get_render_work()
   RenderWork render_work;
 
   if (state_.resolution_divider != pixel_size_) {
-    state_.resolution_divider = max(state_.resolution_divider / 2, pixel_size_);
+    if (state_.user_is_navigating) {
+      /* Don't progress the resolution divider as the user is currently navigating in the scene. */
+      state_.user_is_navigating = false;
+    }
+    else {
+      /* If the resolution divider is greater than or equal to default_start_resolution_divider_,
+       * drop the resolution divider down to 4. This is so users with slow hardware and thus high
+       * resolution dividers (E.G. 16), get an update to let them know something is happening
+       * rather than having to wait for the full 1:1 render to show up. */
+      state_.resolution_divider = state_.resolution_divider > default_start_resolution_divider_ ?
+                                      (4 * pixel_size_) :
+                                      1;
+    }
+
+    state_.resolution_divider = max(state_.resolution_divider, pixel_size_);
     state_.num_rendered_samples = 0;
     state_.last_display_update_sample = -1;
   }
@@ -1058,10 +1071,16 @@ void RenderScheduler::update_start_resolution_divider()
     return;
   }
 
+  /* Calculate the maximum resolution divider possible while keeping the long axis of the viewport
+   * above our prefered minimum axis size (128) */
+  const int long_viewport_axis = max(buffer_params_.width, buffer_params_.height);
+  const int max_res_divider_for_desired_size = long_viewport_axis / 128;
+
   if (start_resolution_divider_ == 0) {
-    /* Resolution divider has never been calculated before: use default resolution, so that we have
-     * somewhat good initial behavior, giving a chance to collect real numbers. */
-    start_resolution_divider_ = default_start_resolution_divider_;
+    /* Resolution divider has never been calculated before: start with a high resolution divider so
+     * that we have a somewhat good initial behavior, giving a chance to collect real numbers. */
+    start_resolution_divider_ = min(default_start_resolution_divider_,
+                                    max_res_divider_for_desired_size);
     VLOG_WORK << "Initial resolution divider is " << start_resolution_divider_;
     return;
   }
@@ -1089,8 +1108,7 @@ void RenderScheduler::update_start_resolution_divider()
 
   /* Don't let resolution drop below the desired one. It's better to be slow than provide an
    * unreadable viewport render. */
-  start_resolution_divider_ = min(resolution_divider_for_update,
-                                  default_start_resolution_divider_);
+  start_resolution_divider_ = min(resolution_divider_for_update, max_res_divider_for_desired_size);
 
   VLOG_WORK << "Calculated resolution divider is " << start_resolution_divider_;
 }

intern/cycles/integrator/render_scheduler.h

@@ -332,6 +332,8 @@ class RenderScheduler {
   };
 
   struct {
+    bool user_is_navigating = false;
+
     int resolution_divider = 1;
 
     /* Number of rendered samples on top of the start sample. */