Bevel Factor Mapping

Bevel Factor Mapping allows to control the relation between bevel factors
(number between 0 and 1) and the rendered start and end point of a beveled
spline.

There are three options: "Resolution", "Segments", "Spline". "Resolution"
option maps bevel factors as it was done < 2.71, "Spline" and "Segments"
are new.

* "Resolution“: Map the bevel factor to the number of subdivisions of a
  spline (U resolution).
* "Segments“: Map the bevel factor to the length of a segment and to the
  number of subdivisions of a segment.
* "Spline": Map the bevel factor to the length of a spline.

Reviewers: yakca, sergey, campbellbarton

CC: sanne

Differential Revision: https://developer.blender.org/D294

6 files changed, 188 insertions, 24 deletions

diff --git a/release/scripts/startup/bl_ui/properties_data_curve.py b/release/scripts/startup/bl_ui/properties_data_curve.py
index 8a3e31d8308..acfc4d1e263 100644
--- a/release/scripts/startup/bl_ui/properties_data_curve.py
+++ b/release/scripts/startup/bl_ui/properties_data_curve.py
@@ -183,13 +183,22 @@ class DATA_PT_geometry_curve(CurveButtonsPanelCurve, Panel):
         col.prop(curve, "bevel_object", text="")
 
         col = layout.column(align=True)
-        col.prop(curve, "bevel_factor_start")
-        col.prop(curve, "bevel_factor_end")
-
         row = col.row()
-        row.active = (curve.bevel_object is not None)
-        row.prop(curve, "use_fill_caps")
+        row.label(text="Bevel Factor:")
+
+        col = layout.column()
+        col.active = (curve.bevel_depth > 0 or curve.bevel_object is not None)
+        row = col.row(align=True)
+        row.prop(curve, "bevel_factor_mapping_start", text="")
+        row.prop(curve, "bevel_factor_start", text="Start")
+        row = col.row(align=True)
+        row.prop(curve, "bevel_factor_mapping_end", text="")
+        row.prop(curve, "bevel_factor_end", text="End")
+
+        row = layout.row()
+        row.active = curve.bevel_object is not None
         row.prop(curve, "use_map_taper")
+        row.prop(curve, "use_fill_caps")
 
 
 class DATA_PT_pathanim(CurveButtonsPanelCurve, Panel):
diff --git a/source/blender/blenkernel/intern/curve.c b/source/blender/blenkernel/intern/curve.c
index 864682c5607..44c9bc9ebbe 100644
--- a/source/blender/blenkernel/intern/curve.c
+++ b/source/blender/blenkernel/intern/curve.c
@@ -182,6 +182,8 @@ Curve *BKE_curve_add(Main *bmain, const char *name, int type)
 	cu->type = type;
 	cu->bevfac1 = 0.0f;
 	cu->bevfac2 = 1.0f;
+	cu->bevfac1_mapping = CU_BEVFAC_MAP_RESOLU;
+	cu->bevfac2_mapping = CU_BEVFAC_MAP_RESOLU;
 
 	cu->bb = BKE_boundbox_alloc_unit();
 
diff --git a/source/blender/blenkernel/intern/displist.c b/source/blender/blenkernel/intern/displist.c
index 33cb2c0fb23..4b251396376 100644
--- a/source/blender/blenkernel/intern/displist.c
+++ b/source/blender/blenkernel/intern/displist.c
@@ -1364,6 +1364,143 @@ static void fillBevelCap(Nurb *nu, DispList *dlb, float *prev_fp, ListBase *disp
 	BLI_addtail(dispbase, dl);
 }
 
+
+static void calc_bevfac_spline_mapping(BevList *bl, float bevfac, float spline_length, const float *bevp_array,
+                                       int *r_bev, float *r_blend)
+{
+	float len = 0.0f;
+	int i;
+	for (i = 0; i < bl->nr; i++) {
+		*r_bev = i;
+		*r_blend = (bevfac * spline_length - len) / bevp_array[i];
+		if (len + bevp_array[i] > bevfac * spline_length) {
+			break;
+		}
+		len += bevp_array[i];
+	}
+}
+
+static void calc_bevfac_mapping(Curve *cu, BevList *bl, int *r_start, float *r_firstblend, int *r_steps, float *r_lastblend)
+{
+	BevPoint *bevp, *bevl;
+	float l, startf, endf, tmpf = 0.0, sum = 0.0, total_length = 0.0f;
+	float *bevp_array = NULL;
+	float *segments = NULL;
+	int end = 0, i, j, segcount = (int)(bl->nr / cu->resolu);
+
+	if ((cu->bevfac1_mapping != CU_BEVFAC_MAP_RESOLU) ||
+	    (cu->bevfac2_mapping != CU_BEVFAC_MAP_RESOLU))
+	{
+		bevp_array = MEM_mallocN(sizeof(bevp_array) * (bl->nr - 1), "bevp_dists");
+		segments = MEM_callocN(sizeof(segments) * segcount, "bevp_segmentlengths");
+		bevp = (BevPoint *)(bl + 1);
+		bevp++;
+		for (i = 1, j = 0; i < bl->nr; bevp++, i++) {
+			sum = 0.0f;
+			bevl = bevp - 1;
+			bevp_array[i - 1] = len_v3v3(bevp->vec, bevl->vec);
+			total_length += bevp_array[i - 1];
+			tmpf += bevp_array[i - 1];
+			if ((i % cu->resolu) == 0 || (bl->nr - 1) == i) {
+				segments[j++] = tmpf;
+				tmpf = 0.0f;
+			}
+		}
+	}
+
+	switch (cu->bevfac1_mapping) {
+		case CU_BEVFAC_MAP_RESOLU:
+		{
+			const float start_fl = cu->bevfac1 * (bl->nr - 1);
+			*r_start = (int)start_fl;
+
+			*r_firstblend = 1.0f - (start_fl - (*r_start));
+			break;
+		}
+		case CU_BEVFAC_MAP_SEGMENT:
+		{
+			const float start_fl = cu->bevfac1 * (bl->nr - 1);
+			*r_start = (int)start_fl;
+
+			for (i = 0; i < segcount; i++) {
+				l = segments[i] / total_length;
+				if (sum + l > cu->bevfac1) {
+					startf = i * cu->resolu + (cu->bevfac1 - sum) / l * cu->resolu;
+					*r_start = (int) startf;
+					*r_firstblend = 1.0f - (startf - *r_start);
+					break;
+				}
+				sum += l;
+			}
+			break;
+		}
+		case CU_BEVFAC_MAP_SPLINE:
+		{
+			calc_bevfac_spline_mapping(bl, cu->bevfac1, total_length, bevp_array, r_start, r_firstblend);
+			*r_firstblend = 1.0f - *r_firstblend;
+			break;
+		}
+	}
+
+	sum = 0.0f;
+	switch (cu->bevfac2_mapping) {
+		case CU_BEVFAC_MAP_RESOLU:
+		{
+			const float end_fl = cu->bevfac2 * (bl->nr - 1);
+			end = (int)end_fl;
+
+			*r_steps = 2 + end - *r_start;
+			*r_lastblend = end_fl - end;
+			break;
+		}
+		case CU_BEVFAC_MAP_SEGMENT:
+		{
+			const float end_fl = cu->bevfac2 * (bl->nr - 1);
+			end = (int)end_fl;
+
+			*r_steps = end - *r_start + 2;
+			for (i = 0; i < segcount; i++) {
+				l = segments[i] / total_length;
+				if (sum + l > cu->bevfac2) {
+					endf = i * cu->resolu + (cu->bevfac2 - sum) / l * cu->resolu;
+					end = (int)endf;
+					*r_lastblend = (endf - end);
+					*r_steps = end - *r_start + 2;
+					break;
+				}
+				sum += l;
+			}
+			break;
+		}
+		case CU_BEVFAC_MAP_SPLINE:
+		{
+			calc_bevfac_spline_mapping(bl, cu->bevfac2, total_length, bevp_array, &end, r_lastblend);
+			*r_steps = end - *r_start + 2;
+			break;
+		}
+	}
+
+	if (end < *r_start) {
+		SWAP(int, *r_start, end);
+		tmpf = *r_lastblend;
+		*r_lastblend = 1.0f - *r_firstblend;
+		*r_firstblend = 1.0f - tmpf;
+		*r_steps = end - *r_start + 2;
+	}
+
+	if (*r_start + *r_steps > bl->nr) {
+		*r_steps = bl->nr - *r_start;
+		*r_lastblend = 1.0f;
+	}
+
+	if (bevp_array) {
+		MEM_freeN(bevp_array);
+	}
+	if (segments) {
+		MEM_freeN(segments);
+	}
+}
+
 static void do_makeDispListCurveTypes(Scene *scene, Object *ob, ListBase *dispbase,
                                       DerivedMesh **r_dm_final,
                                       const bool for_render, const bool for_orco, const bool use_render_resolution)
@@ -1460,25 +1597,12 @@ static void do_makeDispListCurveTypes(Scene *scene, Object *ob, ListBase *dispba
 						ListBase top_capbase = {NULL, NULL};
 						float bottom_no[3] = {0.0f};
 						float top_no[3] = {0.0f};
+						float firstblend = 0.0f, lastblend = 0.0f;
+						int i, start, steps;
+
+						calc_bevfac_mapping(cu, bl, &start, &firstblend, &steps, &lastblend);
 
 						for (dlb = dlbev.first; dlb; dlb = dlb->next) {
-							const float bevfac1 = min_ff(cu->bevfac1, cu->bevfac2);
-							const float bevfac2 = max_ff(cu->bevfac1, cu->bevfac2);
-							float firstblend = 0.0f, lastblend = 0.0f;
-							int i, start, steps;
-
-							if (bevfac2 - bevfac1 == 0.0f)
-								continue;
-
-							start = (int)(bevfac1 * (bl->nr - 1));
-							steps = 2 + (int)((bevfac2) * (bl->nr - 1)) - start;
-							firstblend = 1.0f - (bevfac1 * (bl->nr - 1) - (int)(bevfac1 * (bl->nr - 1)));
-							lastblend  =         bevfac2 * (bl->nr - 1) - (int)(bevfac2 * (bl->nr - 1));
-
-							if (start + steps > bl->nr) {
-								steps = bl->nr - start;
-								lastblend = 1.0f;
-							}
 
 							/* for each part of the bevel use a separate displblock */
 							dl = MEM_callocN(sizeof(DispList), "makeDispListbev1");
diff --git a/source/blender/blenloader/intern/versioning_270.c b/source/blender/blenloader/intern/versioning_270.c
index 30d8bf429f0..8fadfa69fac 100644
--- a/source/blender/blenloader/intern/versioning_270.c
+++ b/source/blender/blenloader/intern/versioning_270.c
@@ -34,6 +34,7 @@
 /* allow readfile to use deprecated functionality */
 #define DNA_DEPRECATED_ALLOW
 
+#include "DNA_curve_types.h"
 #include "DNA_sdna_types.h"
 #include "DNA_space_types.h"
 #include "DNA_screen_types.h"
diff --git a/source/blender/makesdna/DNA_curve_types.h b/source/blender/makesdna/DNA_curve_types.h
index ebba59ec785..0c9e9b01a76 100644
--- a/source/blender/makesdna/DNA_curve_types.h
+++ b/source/blender/makesdna/DNA_curve_types.h
@@ -257,8 +257,10 @@ typedef struct Curve {
 
 	float ctime;			/* current evaltime - for use by Objects parented to curves */
 	float bevfac1, bevfac2;
+	char bevfac1_mapping, bevfac2_mapping;
+
+	char pad2[2];
 
-	char pad2[4];
 } Curve;
 
 /* **************** CURVE ********************* */
@@ -295,6 +297,13 @@ typedef struct Curve {
 #define CU_TWIST_MINIMUM		3
 #define CU_TWIST_TANGENT		4
 
+/* bevel factor mapping */
+enum {
+	CU_BEVFAC_MAP_RESOLU = 0,
+	CU_BEVFAC_MAP_SEGMENT = 1,
+	CU_BEVFAC_MAP_SPLINE = 2
+};
+
 /* spacemode */
 #define CU_LEFT			0
 #define CU_MIDDLE		1
diff --git a/source/blender/makesrna/intern/rna_curve.c b/source/blender/makesrna/intern/rna_curve.c
index ee6d9df1726..31709f90249 100644
--- a/source/blender/makesrna/intern/rna_curve.c
+++ b/source/blender/makesrna/intern/rna_curve.c
@@ -1326,7 +1326,14 @@ static void rna_def_curve(BlenderRNA *brna)
 		 "Allow editing on the Z axis of this curve, also allows tilt and curve radius to be used"},
 		{0, NULL, 0, NULL, NULL}
 	};
-			
+
+	static EnumPropertyItem bevfac_mapping_items[] = {
+		{CU_BEVFAC_MAP_RESOLU, "RESOLUTION", 0, "Resolution", "Map the bevel factor to the number of subdivisions of a spline (U resolution)"},
+		{CU_BEVFAC_MAP_SEGMENT, "SEGMENTS", 0, "Segments", "Map the bevel factor to the length of a segment and to the number of subdivisions of a segment"},
+		{CU_BEVFAC_MAP_SPLINE, "SPLINE", 0, "Spline", "Map the bevel factor to the length of a spline"},
+		{0, NULL, 0, NULL, NULL}
+	};
+
 	srna = RNA_def_struct(brna, "Curve", "ID");
 	RNA_def_struct_ui_text(srna, "Curve", "Curve datablock storing curves, splines and NURBS");
 	RNA_def_struct_ui_icon(srna, ICON_CURVE_DATA);
@@ -1469,6 +1476,18 @@ static void rna_def_curve(BlenderRNA *brna)
 	RNA_def_property_ui_text(prop, "Twist Method", "The type of tilt calculation for 3D Curves");
 	RNA_def_property_update(prop, 0, "rna_Curve_update_data");
 
+	prop = RNA_def_property(srna, "bevel_factor_mapping_start", PROP_ENUM, PROP_NONE);
+	RNA_def_property_enum_sdna(prop, NULL, "bevfac1_mapping");
+	RNA_def_property_enum_items(prop, bevfac_mapping_items);
+	RNA_def_property_ui_text(prop, "Start Mapping Type", "Determines how the start bevel factor is mappend to a spline");
+	RNA_def_property_update(prop, 0, "rna_Curve_update_data");
+
+	prop = RNA_def_property(srna, "bevel_factor_mapping_end", PROP_ENUM, PROP_NONE);
+	RNA_def_property_enum_sdna(prop, NULL, "bevfac2_mapping");
+	RNA_def_property_enum_items(prop, bevfac_mapping_items);
+	RNA_def_property_ui_text(prop, "End Mapping Type", "Determines how the end bevel factor is mappend to a spline");
+	RNA_def_property_update(prop, 0, "rna_Curve_update_data");
+
 	/* XXX - would be nice to have a better way to do this, only add for testing. */
 	prop = RNA_def_property(srna, "twist_smooth", PROP_FLOAT, PROP_NONE);
 	RNA_def_property_float_sdna(prop, NULL, "twist_smooth");