Transform: option to use incremental snapping

This resolves this issue where users would enable a snapping mode
besides incremental (vertex for eg), then notice strange behavior w/
rotate and scale.
While this ability can be useful, it's quite an obscure use case.

Now changing snap-modes keeps rotate and scale using incremental snap,
with the option for these modes to be affected by other snapping modes.

D4022 by @kioku w/ own minor edits.

5 files changed, 63 insertions, 9 deletions

diff --git a/source/blender/blenkernel/intern/scene.c b/source/blender/blenkernel/intern/scene.c
index 3894d83c169..cd0e437ec7e 100644
--- a/source/blender/blenkernel/intern/scene.c
+++ b/source/blender/blenkernel/intern/scene.c
@@ -670,6 +670,7 @@ void BKE_scene_init(Scene *sce)
 	sce->toolsettings->snap_mode = SCE_SNAP_MODE_INCREMENT;
 	sce->toolsettings->snap_node_mode = SCE_SNAP_MODE_GRID;
 	sce->toolsettings->snap_uv_mode = SCE_SNAP_MODE_INCREMENT;
+	sce->toolsettings->snap_force_increment_flag = SCE_SNAP_FORCE_INCREMENT_ROTATE | SCE_SNAP_FORCE_INCREMENT_SCALE;
 
 	sce->toolsettings->curve_paint_settings.curve_type = CU_BEZIER;
 	sce->toolsettings->curve_paint_settings.flag |= CURVE_PAINT_FLAG_CORNERS_DETECT;
diff --git a/source/blender/blenloader/intern/versioning_280.c b/source/blender/blenloader/intern/versioning_280.c
index f3c9d57a67f..4eda9bc7a12 100644
--- a/source/blender/blenloader/intern/versioning_280.c
+++ b/source/blender/blenloader/intern/versioning_280.c
@@ -2737,5 +2737,11 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
 	{
 		/* Versioning code until next subversion bump goes here. */
 
+		if (!DNA_struct_elem_find(fd->filesdna, "ToolSettings", "char", "snap_force_increment_flag")) {
+			for (Scene *scene = bmain->scene.first; scene; scene = scene->id.next) {
+				scene->toolsettings->snap_force_increment_flag =
+					SCE_SNAP_FORCE_INCREMENT_ROTATE | SCE_SNAP_FORCE_INCREMENT_SCALE;
+			}
+		}
 	}
 }
diff --git a/source/blender/editors/transform/transform_snap.c b/source/blender/editors/transform/transform_snap.c
index 6af920c120d..c2c864b51ad 100644
--- a/source/blender/editors/transform/transform_snap.c
+++ b/source/blender/editors/transform/transform_snap.c
@@ -137,6 +137,21 @@ bool activeSnap(const TransInfo *t)
 	       ((t->modifiers & (MOD_SNAP | MOD_SNAP_INVERT)) == MOD_SNAP_INVERT);
 }
 
+static bool doForceIncrementSnap(const TransInfo *t)
+{
+	const ToolSettings *ts = t->settings;
+	if (t->mode == TFM_TRANSLATION) {
+		return ts->snap_force_increment_flag & SCE_SNAP_FORCE_INCREMENT_TRANSLATE;
+	}
+	if (t->mode == TFM_ROTATION) {
+		return ts->snap_force_increment_flag & SCE_SNAP_FORCE_INCREMENT_ROTATE;
+	}
+	if (t->mode == TFM_RESIZE) {
+		return ts->snap_force_increment_flag & SCE_SNAP_FORCE_INCREMENT_SCALE;
+	}
+	return false;
+}
+
 void drawSnapping(const struct bContext *C, TransInfo *t)
 {
 	unsigned char col[4], selectedCol[4], activeCol[4];
@@ -405,8 +420,10 @@ void applyGridAbsolute(TransInfo *t)
 
 void applySnapping(TransInfo *t, float *vec)
 {
-	if (t->tsnap.project && t->tsnap.mode == SCE_SNAP_MODE_FACE) {
-		/* Each Trans Data already makes the snap to face */
+	/* Each Trans Data already makes the snap to face */
+	if (doForceIncrementSnap(t) ||
+	    (t->tsnap.project && t->tsnap.mode == SCE_SNAP_MODE_FACE))
+	{
 		return;
 	}
 
@@ -1450,8 +1467,8 @@ void snapGridIncrement(TransInfo *t, float *val)
 
 	/* only do something if using absolute or incremental grid snapping
 	 * and there is no valid snap point */
-	if (!(t->tsnap.mode & (SCE_SNAP_MODE_INCREMENT | SCE_SNAP_MODE_GRID)) ||
-	    validSnap(t))
+	if ((!(t->tsnap.mode & (SCE_SNAP_MODE_INCREMENT | SCE_SNAP_MODE_GRID)) ||
+	    validSnap(t)) && !doForceIncrementSnap(t))
 	{
 		return;
 	}
@@ -1494,7 +1511,7 @@ static void applyGridIncrement(TransInfo *t, float *val, int max_index, const fl
 	const float *asp = use_aspect ? t->aspect : asp_local;
 	int i;
 
-	BLI_assert(t->tsnap.mode & (SCE_SNAP_MODE_INCREMENT | SCE_SNAP_MODE_GRID));
+	BLI_assert((t->tsnap.mode & (SCE_SNAP_MODE_INCREMENT | SCE_SNAP_MODE_GRID)) || doForceIncrementSnap(t));
 	BLI_assert(max_index <= 2);
 
 	/* Early bailing out if no need to snap */
diff --git a/source/blender/makesdna/DNA_scene_types.h b/source/blender/makesdna/DNA_scene_types.h
index 43f236cde1e..8be63add398 100644
--- a/source/blender/makesdna/DNA_scene_types.h
+++ b/source/blender/makesdna/DNA_scene_types.h
@@ -1330,7 +1330,8 @@ typedef struct ToolSettings {
 	float select_thresh;
 
 	/* Auto-Keying Mode */
-	short autokey_mode, autokey_flag;	/* defines in DNA_userdef_types.h */
+	short autokey_flag;	/* defines in DNA_userdef_types.h */
+	char  autokey_mode;
 	char keyframe_type;                 /* keyframe type (see DNA_curve_types.h) */
 
 	/* Multires */
@@ -1350,13 +1351,15 @@ typedef struct ToolSettings {
 	char snap_uv_mode;
 	char snap_flag;
 	char snap_target;
-	short proportional, prop_mode;
+	char snap_force_increment_flag;
+
+
+	char proportional, prop_mode;
 	char proportional_objects; /* proportional edit, object mode */
 	char proportional_mask; /* proportional edit, mask editing */
 	char proportional_action; /* proportional edit, action editor */
 	char proportional_fcurve; /* proportional edit, graph editor */
 	char lock_markers; /* lock marker editing */
-	char pad4[5];
 
 	char auto_normalize; /*auto normalizing mode in wpaint*/
 	char multipaint; /* paint multiple bones in wpaint */
@@ -1364,7 +1367,7 @@ typedef struct ToolSettings {
 	char vgroupsubset; /* subset selection filter in wpaint */
 
 	/* UV painting */
-	char _pad2[2];
+	char _pad2[1];
 	char use_uv_sculpt;
 	char uv_sculpt_settings;
 	char uv_sculpt_tool;
@@ -1907,6 +1910,13 @@ enum {
 #define SCE_SNAP_MODE_NODE_X    (1 << 6)
 #define SCE_SNAP_MODE_NODE_Y    (1 << 7)
 
+/** #ToolSettings.snap_force_increment_flag */
+enum {
+	SCE_SNAP_FORCE_INCREMENT_TRANSLATE  = (1 << 0),
+	SCE_SNAP_FORCE_INCREMENT_ROTATE     = (1 << 1),
+	SCE_SNAP_FORCE_INCREMENT_SCALE      = (1 << 2),
+};
+
 /* ToolSettings.selectmode */
 #define SCE_SELECT_VERTEX	(1 << 0) /* for mesh */
 #define SCE_SELECT_EDGE		(1 << 1)
diff --git a/source/blender/makesrna/intern/rna_scene.c b/source/blender/makesrna/intern/rna_scene.c
index 4d499b93ab2..52e4c62ea00 100644
--- a/source/blender/makesrna/intern/rna_scene.c
+++ b/source/blender/makesrna/intern/rna_scene.c
@@ -2478,6 +2478,26 @@ static void rna_def_tool_settings(BlenderRNA  *brna)
 	RNA_def_property_ui_text(prop, "Project onto Self", "Snap onto itself (Edit Mode Only)");
 	RNA_def_property_update(prop, NC_SCENE | ND_TOOLSETTINGS, NULL); /* header redraw */
 
+	prop = RNA_def_property(srna, "use_snap_force_increment_translate", PROP_BOOLEAN, PROP_NONE);
+	RNA_def_property_boolean_negative_sdna(prop, NULL, "snap_force_increment_flag", SCE_SNAP_FORCE_INCREMENT_TRANSLATE);
+	RNA_def_property_ui_text(prop, "Resctrict Translation",
+	                         "Translate uses the snapping modes, otherwise use increment snapping");
+	RNA_def_property_update(prop, NC_SCENE | ND_TOOLSETTINGS, NULL); /* header redraw */
+
+	prop = RNA_def_property(srna, "use_snap_force_increment_rotate", PROP_BOOLEAN, PROP_NONE);
+	RNA_def_property_boolean_negative_sdna(prop, NULL, "snap_force_increment_flag", SCE_SNAP_FORCE_INCREMENT_ROTATE);
+	RNA_def_property_boolean_default(prop, false);
+	RNA_def_property_ui_text(prop, "Resctrict Rotate",
+	                         "Rotate uses the snapping modes, otherwise use increment snapping");
+	RNA_def_property_update(prop, NC_SCENE | ND_TOOLSETTINGS, NULL); /* header redraw */
+
+	prop = RNA_def_property(srna, "use_snap_force_increment_scale", PROP_BOOLEAN, PROP_NONE);
+	RNA_def_property_boolean_negative_sdna(prop, NULL, "snap_force_increment_flag", SCE_SNAP_FORCE_INCREMENT_SCALE);
+	RNA_def_property_boolean_default(prop, false);
+	RNA_def_property_ui_text(prop, "Resctrict Scale",
+	                         "Scale uses the snapping modes, otherwise use increment snapping");
+	RNA_def_property_update(prop, NC_SCENE | ND_TOOLSETTINGS, NULL); /* header redraw */
+
 	prop = RNA_def_property(srna, "use_gizmo_mode", PROP_ENUM, PROP_NONE);
 	RNA_def_property_enum_sdna(prop, NULL, "gizmo_flag");
 	RNA_def_property_enum_items(prop, rna_enum_gizmo_items);