Sculpt UI: Make DynTopo constant detail a resolution value

This should make it easier to sculpt in high resolutions, downside is that the new way to calculate maximum edge length is a bit less intuitive. Maximum edge length used to be calculated as blender_unit * percentage_value, now it's blender_unit / value.

Reused old DNA struct member, but had to bump subversion to ensure correct compatibility conversion. Also changed default value slightly (would have had to set to 3.333... otherwise).

Was Requested by @monio (see https://rightclickselect.com/p/sculpting/zpbbbc/dyntopo-better-scale-input-in-constant-detail-mode) and I think it's worth testing.

6 files changed, 34 insertions, 16 deletions

diff --git a/source/blender/blenkernel/BKE_blender_version.h b/source/blender/blenkernel/BKE_blender_version.h
index 908e6f214f9..baf8510dd0d 100644
--- a/source/blender/blenkernel/BKE_blender_version.h
+++ b/source/blender/blenkernel/BKE_blender_version.h
@@ -28,7 +28,7 @@
  * and keep comment above the defines.
  * Use STRINGIFY() rather than defining with quotes */
 #define BLENDER_VERSION         278
-#define BLENDER_SUBVERSION      2
+#define BLENDER_SUBVERSION      3
 /* Several breakages with 270, e.g. constraint deg vs rad */
 #define BLENDER_MINVERSION      270
 #define BLENDER_MINSUBVERSION   6
diff --git a/source/blender/blenloader/intern/versioning_270.c b/source/blender/blenloader/intern/versioning_270.c
index 8e855eb56b8..8133d0496fa 100644
--- a/source/blender/blenloader/intern/versioning_270.c
+++ b/source/blender/blenloader/intern/versioning_270.c
@@ -1427,7 +1427,7 @@ void blo_do_versions_270(FileData *fd, Library *UNUSED(lib), Main *main)
 		}
 	}
 
-	{
+	if (!MAIN_VERSION_ATLEAST(main, 278, 3)) {
 		for (Scene *scene = main->scene.first; scene != NULL; scene = scene->id.next) {
 			if (scene->toolsettings != NULL) {
 				ToolSettings *ts = scene->toolsettings;
@@ -1454,5 +1454,16 @@ void blo_do_versions_270(FileData *fd, Library *UNUSED(lib), Main *main)
 				}
 			}
 		}
+
+		/* constant detail for sculpting is now a resolution value instead of
+		 * a percentage, we reuse old DNA struct member but convert it */
+		for (Scene *scene = main->scene.first; scene != NULL; scene = scene->id.next) {
+			if (scene->toolsettings != NULL) {
+				ToolSettings *ts = scene->toolsettings;
+				if (ts->sculpt && ts->sculpt->constant_detail != 0.0f) {
+					ts->sculpt->constant_detail = 100.0f / ts->sculpt->constant_detail;
+				}
+			}
+		}
 	}
 }
diff --git a/source/blender/editors/interface/resources.c b/source/blender/editors/interface/resources.c
index 5e24dc96255..539284030c2 100644
--- a/source/blender/editors/interface/resources.c
+++ b/source/blender/editors/interface/resources.c
@@ -2750,17 +2750,21 @@ void init_userdef_do_versions(void)
 		}
 	}
 
+	if (!USER_VERSION_ATLEAST(278, 3)) {
+		for (bTheme *btheme = U.themes.first; btheme; btheme = btheme->next) {
+			/* Keyframe Indicators (were using wrong alpha) */
+			btheme->tv3d.time_keyframe[3] = btheme->tv3d.time_gp_keyframe[3] = 255;
+			btheme->ttime.time_keyframe[3] = btheme->ttime.time_gp_keyframe[3] = 255;
+		}
+	}
+
 	/**
 	 * Include next version bump.
 	 *
 	 * (keep this block even if it becomes empty).
 	 */
 	{
-		for (bTheme *btheme = U.themes.first; btheme; btheme = btheme->next) {
-			/* Keyframe Indicators (were using wrong alpha) */
-			btheme->tv3d.time_keyframe[3] = btheme->tv3d.time_gp_keyframe[3] = 255;
-			btheme->ttime.time_keyframe[3] = btheme->ttime.time_gp_keyframe[3] = 255;
-		}
+		
 	}
 
 	if (U.pixelsize == 0.0f)
diff --git a/source/blender/editors/sculpt_paint/sculpt.c b/source/blender/editors/sculpt_paint/sculpt.c
index fe0fb3f5035..53434b18d06 100644
--- a/source/blender/editors/sculpt_paint/sculpt.c
+++ b/source/blender/editors/sculpt_paint/sculpt.c
@@ -4688,7 +4688,7 @@ static void sculpt_stroke_update_step(bContext *C, struct PaintStroke *UNUSED(st
 	sculpt_restore_mesh(sd, ob);
 
 	if (sd->flags & SCULPT_DYNTOPO_DETAIL_CONSTANT) {
-		BKE_pbvh_bmesh_detail_size_set(ss->pbvh, sd->constant_detail / 100.0f);
+		BKE_pbvh_bmesh_detail_size_set(ss->pbvh, 1.0f / sd->constant_detail);
 	}
 	else if (sd->flags & SCULPT_DYNTOPO_DETAIL_BRUSH) {
 		BKE_pbvh_bmesh_detail_size_set(ss->pbvh, ss->cache->radius * sd->detail_percent / 100.0f);
@@ -5406,7 +5406,7 @@ static int sculpt_mode_toggle_exec(bContext *C, wmOperator *op)
 		if (!ts->sculpt->detail_percent)
 			ts->sculpt->detail_percent = 25;
 		if (ts->sculpt->constant_detail == 0.0f)
-			ts->sculpt->constant_detail = 30.0f;
+			ts->sculpt->constant_detail = 3.0f;
 
 		/* Set sane default tiling offsets */
 		if (!ts->sculpt->paint.tile_offset[0]) ts->sculpt->paint.tile_offset[0] = 1.0f;
@@ -5543,7 +5543,7 @@ static int sculpt_detail_flood_fill_exec(bContext *C, wmOperator *UNUSED(op))
 	size = max_fff(bb_max[0], bb_max[1], bb_max[2]);
 
 	/* update topology size */
-	BKE_pbvh_bmesh_detail_size_set(ss->pbvh, sd->constant_detail / 100.0f);
+	BKE_pbvh_bmesh_detail_size_set(ss->pbvh, 1.0f / sd->constant_detail);
 
 	sculpt_undo_push_begin("Dynamic topology flood fill");
 	sculpt_undo_push_node(ob, NULL, SCULPT_UNDO_COORDS);
@@ -5608,7 +5608,8 @@ static void sample_detail(bContext *C, int ss_co[2])
 	                 ray_start, ray_normal, false);
 
 	if (srd.hit) {
-		sd->constant_detail = srd.detail * 100.0f;
+		/* convert edge length to detail resolution */
+		sd->constant_detail = 1.0f / srd.detail;
 	}
 }
 
diff --git a/source/blender/makesdna/DNA_scene_types.h b/source/blender/makesdna/DNA_scene_types.h
index 9b0781ebe70..f5e71ae59a9 100644
--- a/source/blender/makesdna/DNA_scene_types.h
+++ b/source/blender/makesdna/DNA_scene_types.h
@@ -1103,7 +1103,7 @@ typedef struct Sculpt {
 	float gravity_factor;
 
 	/* scale for constant detail size */
-	float constant_detail;
+	float constant_detail; /* Constant detail resolution (Blender unit / constant_detail) */
 	float detail_percent;
 	float pad;
 
diff --git a/source/blender/makesrna/intern/rna_sculpt_paint.c b/source/blender/makesrna/intern/rna_sculpt_paint.c
index e169ef0d822..7f405f0fb1f 100644
--- a/source/blender/makesrna/intern/rna_sculpt_paint.c
+++ b/source/blender/makesrna/intern/rna_sculpt_paint.c
@@ -600,10 +600,12 @@ static void rna_def_sculpt(BlenderRNA  *brna)
 	RNA_def_property_ui_text(prop, "Detail Percentage", "Maximum edge length for dynamic topology sculpting (in brush percenage)");
 	RNA_def_property_update(prop, NC_SCENE | ND_TOOLSETTINGS, NULL);
 
-	prop = RNA_def_property(srna, "constant_detail", PROP_FLOAT, PROP_PERCENTAGE);
-	RNA_def_property_range(prop, 0.001, 10000.0);
-	RNA_def_property_ui_range(prop, 0.1, 100.0, 10, 2);
-	RNA_def_property_ui_text(prop, "Detail Size", "Maximum edge length for dynamic topology sculpting (as percentage of blender unit)");
+	prop = RNA_def_property(srna, "constant_detail_resolution", PROP_FLOAT, PROP_NONE);
+	RNA_def_property_float_sdna(prop, NULL, "constant_detail");
+	RNA_def_property_range(prop, 0.0001, FLT_MAX);
+	RNA_def_property_ui_range(prop, 0.001, 1000.0, 10, 2);
+	RNA_def_property_ui_text(prop, "Resolution", "Maximum edge length for dynamic topology sculpting (as divisor "
+	                         "of blender unit - higher value means smaller edge length)");
 	RNA_def_property_update(prop, NC_SCENE | ND_TOOLSETTINGS, NULL);
 
 	prop = RNA_def_property(srna, "use_smooth_shading", PROP_BOOLEAN, PROP_NONE);