1 files changed, 102 insertions, 5 deletions

diff --git a/source/blender/gpencil_modifiers/intern/MOD_gpencillength.c b/source/blender/gpencil_modifiers/intern/MOD_gpencillength.c
index 80b60547e92..af0067e06aa 100644
--- a/source/blender/gpencil_modifiers/intern/MOD_gpencillength.c
+++ b/source/blender/gpencil_modifiers/intern/MOD_gpencillength.c
@@ -23,8 +23,10 @@
 
 #include <stdio.h>
 
+#include "BLI_hash.h"
 #include "BLI_listbase.h"
 #include "BLI_math.h"
+#include "BLI_rand.h"
 #include "BLI_utildefines.h"
 
 #include "BLT_translation.h"
@@ -56,6 +58,7 @@
 #include "MOD_gpencil_util.h"
 
 #include "DEG_depsgraph.h"
+#include "DEG_depsgraph_query.h"
 
 static void initData(GpencilModifierData *md)
 {
@@ -71,6 +74,20 @@ static void copyData(const GpencilModifierData *md, GpencilModifierData *target)
   BKE_gpencil_modifier_copydata_generic(md, target);
 }
 
+static float *noise_table(int len, int offset, int seed)
+{
+  float *table = MEM_callocN(sizeof(float) * len, __func__);
+  for (int i = 0; i < len; i++) {
+    table[i] = BLI_hash_int_01(BLI_hash_int_2d(seed, i + offset + 1));
+  }
+  return table;
+}
+
+BLI_INLINE float table_sample(float *table, float x)
+{
+  return interpf(table[(int)ceilf(x)], table[(int)floor(x)], fractf(x));
+}
+
 static bool gpencil_modify_stroke(bGPDstroke *gps,
                                   const float length,
                                   const float overshoot_fac,
@@ -104,9 +121,15 @@ static bool gpencil_modify_stroke(bGPDstroke *gps,
   return changed;
 }
 
-static void applyLength(LengthGpencilModifierData *lmd, bGPdata *gpd, bGPDstroke *gps)
+static void applyLength(GpencilModifierData *md,
+                        Depsgraph *depsgraph,
+                        bGPdata *gpd,
+                        bGPDframe *gpf,
+                        bGPDstroke *gps,
+                        Object *ob)
 {
   bool changed = false;
+  LengthGpencilModifierData *lmd = (LengthGpencilModifierData *)md;
   const float len = (lmd->mode == GP_LENGTH_ABSOLUTE) ? 1.0f :
                                                         BKE_gpencil_stroke_length(gps, true);
   const int totpoints = gps->totpoints;
@@ -120,11 +143,48 @@ static void applyLength(LengthGpencilModifierData *lmd, bGPdata *gpd, bGPDstroke
   int first_mode = 1;
   float second_fac = lmd->end_fac;
   int second_mode = 2;
+
+  float rand[2] = {0.0f, 0.0f};
+  if (lmd->rand_start_fac != 0.0 || lmd->rand_end_fac != 0.0) {
+    int seed = lmd->seed;
+
+    /* Make sure different modifiers get different seeds. */
+    seed += BLI_hash_string(ob->id.name + 2);
+    seed += BLI_hash_string(md->name);
+
+    if (lmd->flag & GP_LENGTH_USE_RANDOM) {
+      seed += ((int)DEG_get_ctime(depsgraph)) / lmd->step;
+    }
+
+    float rand_offset = BLI_hash_int_01(seed);
+
+    /* Get stroke index for random offset. */
+    int rnd_index = BLI_findindex(&gpf->strokes, gps);
+    const uint primes[2] = {2, 3};
+    double offset[2] = {0.0f, 0.0f};
+    double r[2];
+
+    float *noise_table_length = noise_table(4, (int)floor(lmd->rand_offset), seed + 2);
+
+    /* To ensure a nice distribution, we use halton sequence and offset using the seed. */
+    BLI_halton_2d(primes, offset, rnd_index, r);
+    for (int j = 0; j < 2; j++) {
+      float noise = table_sample(noise_table_length, j * 2 + fractf(lmd->rand_offset));
+
+      rand[j] = fmodf(r[j] + rand_offset, 1.0f);
+      rand[j] = fabs(fmodf(sin(rand[j] * 12.9898f + j * 78.233f) * 43758.5453f, 1.0f) + noise);
+    }
+
+    MEM_SAFE_FREE(noise_table_length);
+
+    first_fac = first_fac + rand[0] * lmd->rand_start_fac;
+    second_fac = second_fac + rand[1] * lmd->rand_end_fac;
+  }
+
   if (first_fac < 0) {
     SWAP(float, first_fac, second_fac);
     SWAP(int, first_mode, second_mode);
   }
-
   const int first_extra_point_count = ceil(first_fac * lmd->point_density);
   const int second_extra_point_count = ceil(second_fac * lmd->point_density);
 
@@ -161,10 +221,10 @@ static void applyLength(LengthGpencilModifierData *lmd, bGPdata *gpd, bGPDstroke
 }
 
 static void deformStroke(GpencilModifierData *md,
-                         Depsgraph *UNUSED(depsgraph),
+                         Depsgraph *depsgraph,
                          Object *ob,
                          bGPDlayer *gpl,
-                         bGPDframe *UNUSED(gpf),
+                         bGPDframe *gpf,
                          bGPDstroke *gps)
 {
   bGPdata *gpd = ob->data;
@@ -187,7 +247,7 @@ static void deformStroke(GpencilModifierData *md,
     /* Don't affect cyclic strokes as they have no start/end. */
     return;
   }
-  applyLength(lmd, gpd, gps);
+  applyLength(md, depsgraph, gpd, gpf, gps, ob);
 }
 
 static void bakeModifier(Main *UNUSED(bmain),
@@ -214,6 +274,39 @@ static void foreachIDLink(GpencilModifierData *md, Object *ob, IDWalkFunc walk,
   walk(userData, ob, (ID **)&mmd->material, IDWALK_CB_USER);
 }
 
+static void random_header_draw(const bContext *UNUSED(C), Panel *panel)
+{
+  uiLayout *layout = panel->layout;
+
+  PointerRNA *ptr = gpencil_modifier_panel_get_property_pointers(panel, NULL);
+
+  uiItemR(layout, ptr, "use_random", 0, IFACE_("Randomize"), ICON_NONE);
+}
+
+static void random_panel_draw(const bContext *UNUSED(C), Panel *panel)
+{
+  uiLayout *layout = panel->layout;
+
+  PointerRNA *ptr = gpencil_modifier_panel_get_property_pointers(panel, NULL);
+
+  uiLayoutSetPropSep(layout, true);
+
+  uiLayoutSetActive(layout, RNA_boolean_get(ptr, "use_random"));
+
+  uiItemR(layout, ptr, "step", 0, NULL, ICON_NONE);
+}
+
+static void offset_panel_draw(const bContext *UNUSED(C), Panel *panel)
+{
+  uiLayout *layout = panel->layout;
+  PointerRNA *ptr = gpencil_modifier_panel_get_property_pointers(panel, NULL);
+  uiLayoutSetPropSep(layout, true);
+  uiItemR(layout, ptr, "random_start_factor", 0, IFACE_("Random Offset Start"), ICON_NONE);
+  uiItemR(layout, ptr, "random_end_factor", 0, IFACE_("Random Offset End"), ICON_NONE);
+  uiItemR(layout, ptr, "random_offset", 0, NULL, ICON_NONE);
+  uiItemR(layout, ptr, "seed", 0, NULL, ICON_NONE);
+}
+
 static void panel_draw(const bContext *UNUSED(C), Panel *panel)
 {
   uiLayout *layout = panel->layout;
@@ -277,6 +370,10 @@ static void panelRegister(ARegionType *region_type)
       region_type, eGpencilModifierType_Length, panel_draw);
   gpencil_modifier_subpanel_register(
       region_type, "curvature", "", curvature_header_draw, curvature_panel_draw, panel_type);
+  PanelType *offset_panel = gpencil_modifier_subpanel_register(
+      region_type, "offset", "Random Offsets", NULL, offset_panel_draw, panel_type);
+  gpencil_modifier_subpanel_register(
+      region_type, "randomize", "", random_header_draw, random_panel_draw, offset_panel);
   gpencil_modifier_subpanel_register(
       region_type, "mask", "Influence", NULL, mask_panel_draw, panel_type);
 }