Fix T59686: snap to adaptive grid occurs with a "delay"

In blender 2.8, when you zoom in, the adaptive subdivisions appear earlier than previous versions.
The grid still appears a little before the snap, but since it is very small I see no advantage in snap for this case.

1 files changed, 10 insertions, 11 deletions

diff --git a/source/blender/editors/space_view3d/view3d_draw.c b/source/blender/editors/space_view3d/view3d_draw.c
index 9fee8f38533..b6ded48d53f 100644
--- a/source/blender/editors/space_view3d/view3d_draw.c
+++ b/source/blender/editors/space_view3d/view3d_draw.c
@@ -791,19 +791,18 @@ float ED_view3d_grid_view_scale(
 		/* Decrease the distance between grid snap points depending on zoom. */
 		float grid_subdiv = v3d->gridsubdiv;
 		if (grid_subdiv > 1) {
+			/* Allow 3 more subdivisions (see OBJECT_engine_init). */
+			grid_scale /= powf(grid_subdiv, 3);
+
 			float grid_distance = rv3d->dist;
 			float lvl = (logf(grid_distance / grid_scale) / logf(grid_subdiv));
-			if (lvl < 0.0f) {
-				/* Negative values need an offset for correct casting.
-				 * By convention, the minimum lvl is limited to -2 (see `objec_mode.c`) */
-				if (lvl > -2.0f) {
-					lvl -= 1.0f;
-				}
-				else {
-					lvl = -2.0f;
-				}
-			}
-			grid_scale *= pow(grid_subdiv, (int)lvl - 1);
+
+			/* 1.3f is a visually chosen offset for the
+			 * subdivision to match the displayed grid. */
+			lvl -= 1.3f;
+			CLAMP_MIN(lvl, 0.0f);
+
+			grid_scale *= pow(grid_subdiv, (int)lvl);
 		}
 	}