GPencil: Fading based on distance to reference object in Opacity and Thickness modifiers

This patch allows you to dynamically control stroke's opacity and thickness using an object for distance reference in the modifier. Fading range is adjustable, and it is compatible with current curve/vertex group selection.

Reviewed By: #grease_pencil, antoniov, mendio

Maniphest Tasks: T82177, T80194

Differential Revision: https://developer.blender.org/D9091

1 files changed, 66 insertions, 0 deletions

diff --git a/source/blender/makesrna/intern/rna_gpencil_modifier.c b/source/blender/makesrna/intern/rna_gpencil_modifier.c
index b118adea14f..7d54bad803c 100644
--- a/source/blender/makesrna/intern/rna_gpencil_modifier.c
+++ b/source/blender/makesrna/intern/rna_gpencil_modifier.c
@@ -351,6 +351,8 @@ static void greasepencil_modifier_object_set(Object *self,
 RNA_GP_MOD_OBJECT_SET(Armature, object, OB_ARMATURE);
 RNA_GP_MOD_OBJECT_SET(Lattice, object, OB_LATTICE);
 RNA_GP_MOD_OBJECT_SET(Mirror, object, OB_EMPTY);
+RNA_GP_MOD_OBJECT_SET(Opacity, object, OB_EMPTY);
+RNA_GP_MOD_OBJECT_SET(Thick, object, OB_EMPTY);
 
 #  undef RNA_GP_MOD_OBJECT_SET
 
@@ -1116,6 +1118,38 @@ static void rna_def_modifier_gpencilthick(BlenderRNA *brna)
   RNA_def_property_ui_text(prop, "Thickness Factor", "Factor to multiply the thickness with");
   RNA_def_property_update(prop, 0, "rna_GpencilModifier_update");
 
+  prop = RNA_def_property(srna, "use_fading", PROP_BOOLEAN, PROP_NONE);
+  RNA_def_property_boolean_sdna(prop, NULL, "flag", GP_THICK_FADING);
+  RNA_def_property_ui_text(prop, "Fading", "Fading effect");
+  RNA_def_property_update(prop, 0, "rna_GpencilModifier_update");
+
+  /* Distance reference object */
+  prop = RNA_def_property(srna, "object", PROP_POINTER, PROP_NONE);
+  RNA_def_property_ui_text(prop, "Object", "Object used as distance reference");
+  RNA_def_property_pointer_funcs(prop, NULL, "rna_ThickGpencilModifier_object_set", NULL, NULL);
+  RNA_def_property_flag(prop, PROP_EDITABLE | PROP_ID_SELF_CHECK);
+  RNA_def_property_override_flag(prop, PROPOVERRIDE_OVERRIDABLE_LIBRARY);
+  RNA_def_property_update(prop, 0, "rna_GpencilModifier_dependency_update");
+
+  prop = RNA_def_property(srna, "fading_start", PROP_FLOAT, PROP_NONE);
+  RNA_def_property_float_sdna(prop, NULL, "fading_start");
+  RNA_def_property_ui_range(prop, 0, 1000.0, 1.0, 2);
+  RNA_def_property_ui_text(prop, "Fading Start", "Start distance of fading effect");
+  RNA_def_property_update(prop, 0, "rna_GpencilModifier_update");
+
+  prop = RNA_def_property(srna, "fading_end", PROP_FLOAT, PROP_NONE);
+  RNA_def_property_float_sdna(prop, NULL, "fading_end");
+  RNA_def_property_ui_range(prop, 0, 1000.0, 1.0, 2);
+  RNA_def_property_ui_text(prop, "Fading End", "End distance of fading effect");
+  RNA_def_property_update(prop, 0, "rna_GpencilModifier_update");
+
+  prop = RNA_def_property(srna, "fading_end_factor", PROP_FLOAT, PROP_NONE);
+  RNA_def_property_float_sdna(prop, NULL, "fading_end_factor");
+  RNA_def_property_range(prop, 0.0, FLT_MAX);
+  RNA_def_property_ui_range(prop, 0.0, 10.0, 0.1, 3);
+  RNA_def_property_ui_text(prop, "End Factor", "Fading end thickness factor");
+  RNA_def_property_update(prop, 0, "rna_GpencilModifier_update");
+
   prop = RNA_def_property(srna, "pass_index", PROP_INT, PROP_NONE);
   RNA_def_property_int_sdna(prop, NULL, "pass_index");
   RNA_def_property_range(prop, 0, 100);
@@ -1625,6 +1659,38 @@ static void rna_def_modifier_gpencilopacity(BlenderRNA *brna)
   RNA_def_property_ui_text(prop, "Hardness", "Factor of stroke hardness");
   RNA_def_property_update(prop, 0, "rna_GpencilModifier_update");
 
+  prop = RNA_def_property(srna, "use_fading", PROP_BOOLEAN, PROP_NONE);
+  RNA_def_property_boolean_sdna(prop, NULL, "flag", GP_OPACITY_FADING);
+  RNA_def_property_ui_text(prop, "Fading", "Fading effect");
+  RNA_def_property_update(prop, 0, "rna_GpencilModifier_update");
+
+  /* Distance reference object */
+  prop = RNA_def_property(srna, "object", PROP_POINTER, PROP_NONE);
+  RNA_def_property_ui_text(prop, "Object", "Object used as distance reference");
+  RNA_def_property_pointer_funcs(prop, NULL, "rna_OpacityGpencilModifier_object_set", NULL, NULL);
+  RNA_def_property_flag(prop, PROP_EDITABLE | PROP_ID_SELF_CHECK);
+  RNA_def_property_override_flag(prop, PROPOVERRIDE_OVERRIDABLE_LIBRARY);
+  RNA_def_property_update(prop, 0, "rna_GpencilModifier_dependency_update");
+
+  prop = RNA_def_property(srna, "fading_start", PROP_FLOAT, PROP_NONE);
+  RNA_def_property_float_sdna(prop, NULL, "fading_start");
+  RNA_def_property_ui_range(prop, 0, 1000.0, 1.0, 2);
+  RNA_def_property_ui_text(prop, "Fading Start", "Start distance of fading effect");
+  RNA_def_property_update(prop, 0, "rna_GpencilModifier_update");
+
+  prop = RNA_def_property(srna, "fading_end", PROP_FLOAT, PROP_NONE);
+  RNA_def_property_float_sdna(prop, NULL, "fading_end");
+  RNA_def_property_ui_range(prop, 0, 1000.0, 1.0, 2);
+  RNA_def_property_ui_text(prop, "Fading End", "End distance of fading effect");
+  RNA_def_property_update(prop, 0, "rna_GpencilModifier_update");
+
+  prop = RNA_def_property(srna, "fading_end_factor", PROP_FLOAT, PROP_NONE);
+  RNA_def_property_float_sdna(prop, NULL, "fading_end_factor");
+  RNA_def_property_range(prop, 0.0, FLT_MAX);
+  RNA_def_property_ui_range(prop, 0.0, 10.0, 0.1, 3);
+  RNA_def_property_ui_text(prop, "End Factor", "Fading end thickness factor");
+  RNA_def_property_update(prop, 0, "rna_GpencilModifier_update");
+
   prop = RNA_def_property(srna, "pass_index", PROP_INT, PROP_NONE);
   RNA_def_property_int_sdna(prop, NULL, "pass_index");
   RNA_def_property_range(prop, 0, 100);