LineArt: Smooth tolerance value for chaining.

smooth out jaggy lines with a given threshold. For each point in a stroke, the ones with in a given distance of its previous segment will be removed,
thus "zig-zag" artefacts can be cleaned up.

Reviewed By: Antonio Vazquez (antoniov)

Differential Revision: https://developer.blender.org/D12050

release/datafiles/locale

@@ -1 +1 @@
-Subproject commit 94c39b5832b9ef3b56ed94ce4011412e3d776eb2
+Subproject commit 4833954c0ac85cc407e1d5a153aa11b1d1823ec0

release/scripts/addons

@@ -1 +1 @@
-Subproject commit ecf30de46c368ffddad259c125402a38e6093382
+Subproject commit f86f25e62217264495d05f116ccb09d575fe9841

release/scripts/addons_contrib

@@ -1 +1 @@
-Subproject commit 42da56aa73726710107031787af5eea186797984
+Subproject commit 5a82baad9f986722104280e8354a4427d8e9eab1

source/blender/blenloader/intern/versioning_300.c

@@ -1127,6 +1127,15 @@ void blo_do_versions_300(FileData *fd, Library *UNUSED(lib), Main *bmain)
             }
           }
         }
+        if (ob->type == OB_GPENCIL) {
+          LISTBASE_FOREACH (GpencilModifierData *, md, &ob->greasepencil_modifiers) {
+            if (md->type == eGpencilModifierType_Lineart) {
+              LineartGpencilModifierData *lmd = (LineartGpencilModifierData *)md;
+              lmd->flags |= LRT_GPENCIL_USE_CACHE;
+              lmd->chain_smooth_tolerance = 0.2f;
+            }
+          }
+        }
       }
     }
 

source/blender/gpencil_modifiers/intern/MOD_gpencillineart.c

@@ -587,6 +587,7 @@ static void chaining_panel_draw(const bContext *UNUSED(C), Panel *panel)
           is_geom ? IFACE_("Geometry Threshold") : NULL,
           ICON_NONE);
 
+  uiItemR(layout, ptr, "smooth_tolerance", UI_ITEM_R_SLIDER, NULL, ICON_NONE);
   uiItemR(layout, ptr, "split_angle", UI_ITEM_R_SLIDER, NULL, ICON_NONE);
 }
 

source/blender/gpencil_modifiers/intern/lineart/MOD_lineart.h

@@ -317,6 +317,8 @@ typedef struct LineartRenderBuffer {
   float chaining_image_threshold;
   float angle_splitting_threshold;
 
+  float chain_smooth_tolerance;
+
   /* FIXME(Yiming): Temporary solution for speeding up calculation by not including lines that
    * are not in the selected source. This will not be needed after we have a proper scene-wise
    * cache running because multiple modifiers can then select results from that without further
@@ -592,6 +594,7 @@ void MOD_lineart_chain_split_for_fixed_occlusion(LineartRenderBuffer *rb);
 void MOD_lineart_chain_connect(LineartRenderBuffer *rb);
 void MOD_lineart_chain_discard_short(LineartRenderBuffer *rb, const float threshold);
 void MOD_lineart_chain_split_angle(LineartRenderBuffer *rb, float angle_threshold_rad);
+void MOD_lineart_smooth_chains(LineartRenderBuffer *rb, float tolerance);
 
 int MOD_lineart_chain_count(const LineartEdgeChain *ec);
 void MOD_lineart_chain_clear_picked_flag(LineartCache *lc);

source/blender/gpencil_modifiers/intern/lineart/lineart_chain.c

@@ -924,6 +924,34 @@ void MOD_lineart_chain_clear_picked_flag(LineartCache *lc)
   }
 }
 
+void MOD_lineart_smooth_chains(LineartRenderBuffer *rb, float tolerance)
+{
+  LISTBASE_FOREACH (LineartEdgeChain *, rlc, &rb->chains) {
+    LineartEdgeChainItem *next_eci;
+    for (LineartEdgeChainItem *eci = rlc->chain.first; eci; eci = next_eci) {
+      next_eci = eci->next;
+      LineartEdgeChainItem *eci2, *eci3, *eci4;
+
+      /* Not enough point to do simplify. */
+      if ((!(eci2 = eci->next)) || (!(eci3 = eci2->next))) {
+        continue;
+      }
+
+      /* No need to care for different line types/occlusion and so on, because at this stage they
+       * are all the same within a chain. */
+
+      /* If p3 is within the p1-p2 segment of a width of "tolerance"  */
+      if (dist_to_line_segment_v2(eci3->pos, eci->pos, eci2->pos) < tolerance) {
+        /* And if p4 is on the extension of p1-p2 , we remove p3. */
+        if ((eci4 = eci3->next) && (dist_to_line_v2(eci4->pos, eci->pos, eci2->pos) < tolerance)) {
+          BLI_remlink(&rlc->chain, eci3);
+          next_eci = eci;
+        }
+      }
+    }
+  }
+}
+
 /**
  * This should always be the last stage!, see the end of
  * #MOD_lineart_chain_split_for_fixed_occlusion().

source/blender/gpencil_modifiers/intern/lineart/lineart_cpu.c

@@ -3056,8 +3056,9 @@ static LineartRenderBuffer *lineart_create_render_buffer(Scene *scene,
   rb->shift_y /= (1 + rb->overscan);
 
   rb->crease_threshold = cos(M_PI - lmd->crease_threshold);
-  rb->angle_splitting_threshold = lmd->angle_splitting_threshold;
   rb->chaining_image_threshold = lmd->chaining_image_threshold;
+  rb->angle_splitting_threshold = lmd->angle_splitting_threshold;
+  rb->chain_smooth_tolerance = lmd->chain_smooth_tolerance;
 
   rb->fuzzy_intersections = (lmd->calculation_flags & LRT_INTERSECTION_AS_CONTOUR) != 0;
   rb->fuzzy_everything = (lmd->calculation_flags & LRT_EVERYTHING_AS_CONTOUR) != 0;
@@ -4172,6 +4173,13 @@ bool MOD_lineart_compute_feature_lines(Depsgraph *depsgraph,
     /* This configuration ensures there won't be accidental lost of short unchained segments. */
     MOD_lineart_chain_discard_short(rb, MIN2(*t_image, 0.001f) - FLT_EPSILON);
 
+    if (rb->chain_smooth_tolerance > FLT_EPSILON) {
+      /* Keeping UI range of 0-1 for ease of read while scaling down the actual value for best
+       * effective range in image-space (Coordinate only goes from -1 to 1). This value is somewhat
+       * arbitrary, but works best for the moment.  */
+      MOD_lineart_smooth_chains(rb, rb->chain_smooth_tolerance / 50);
+    }
+
     if (rb->angle_splitting_threshold > FLT_EPSILON) {
       MOD_lineart_chain_split_angle(rb, rb->angle_splitting_threshold);
     }

source/blender/makesdna/DNA_gpencil_modifier_defaults.h

@@ -318,7 +318,7 @@
     .calculation_flags = LRT_ALLOW_DUPLI_OBJECTS | LRT_ALLOW_CLIPPING_BOUNDARIES | LRT_USE_CREASE_ON_SHARP_EDGES, \
     .angle_splitting_threshold = DEG2RAD(60.0f), \
     .chaining_image_threshold = 0.001f, \
-    .overscan = 0.1f,\
+    .chain_smooth_tolerance = 0.2f,\
   }
 
 #define _DNA_DEFAULT_LengthGpencilModifierData \

source/blender/makesdna/DNA_gpencil_modifier_types.h

@@ -1040,7 +1040,11 @@ typedef struct LineartGpencilModifierData {
   /** `0..PI` angle, for splitting strokes at sharp points. */
   float angle_splitting_threshold;
 
-  /* Doubles as geometry threshold when geometry space chaining is enabled */
+  /** Strength for smoothing jagged chains. */
+  float chain_smooth_tolerance;
+  int _pad1;
+
+  /* CPU mode */
   float chaining_image_threshold;
 
   /* Ported from SceneLineArt flags. */

source/blender/makesdna/DNA_gpencil_types.h

@@ -49,6 +49,8 @@ struct MDeformVert;
 #define GPENCIL_MIN_FILL_FAC 0.05f
 #define GPENCIL_MAX_FILL_FAC 8.0f
 
+#define GPENCIL_MAX_THICKNESS 5000
+
 /* ***************************************** */
 /* GP Stroke Points */
 

source/blender/makesrna/intern/rna_gpencil_modifier.c

@@ -26,6 +26,7 @@
 #include "DNA_brush_types.h"
 #include "DNA_cachefile_types.h"
 #include "DNA_gpencil_modifier_types.h"
+#include "DNA_gpencil_types.h"
 #include "DNA_mesh_types.h"
 #include "DNA_object_force_types.h"
 #include "DNA_object_types.h"
@@ -3125,6 +3126,14 @@ static void rna_def_modifier_gpencillineart(BlenderRNA *brna)
   RNA_def_property_range(prop, 0.0f, DEG2RAD(180.0f));
   RNA_def_property_update(prop, NC_SCENE, "rna_GpencilModifier_update");
 
+  prop = RNA_def_property(srna, "smooth_tolerance", PROP_FLOAT, PROP_NONE);
+  RNA_def_property_float_sdna(prop, NULL, "chain_smooth_tolerance");
+  RNA_def_property_ui_text(
+      prop, "Smooth Tolerance", "Strength of smoothing applied on jagged chains");
+  RNA_def_property_ui_range(prop, 0.0f, 1.0f, 0.05f, 4);
+  RNA_def_property_range(prop, 0.0f, 30.0f);
+  RNA_def_property_update(prop, NC_SCENE, "rna_GpencilModifier_update");
+
   prop = RNA_def_property(srna, "use_remove_doubles", PROP_BOOLEAN, PROP_NONE);
   RNA_def_property_boolean_sdna(prop, NULL, "calculation_flags", LRT_REMOVE_DOUBLES);
   RNA_def_property_ui_text(

source/tools

@@ -1 +1 @@
-Subproject commit 723b24841df1ed8478949bca20c73878fab00dca
+Subproject commit 01f51a0e551ab730f0934dc6488613690ac4bf8f