From 591db72ee2ee4c731968754f0be288e9222c012d Mon Sep 17 00:00:00 2001
From: Antonio Vazquez <blendergit@gmail.com>
Date: Mon, 2 Sep 2019 13:31:05 +0200
Subject: GPencil: New Strength mode for Opacity modifier

This new option applies the opacity using the strength of the stroke instead to use the alpha channel of the material.

Tested in greasepencil-object branch

{F7712796}

The vertex group filter has been removed because this filter is not logic in Material mode and must be valid only in Strength mode.

{F7713147}

Reviewers: pepeland, mendio

Reviewed By: mendio

Differential Revision: https://developer.blender.org/D5650
---
 .../gpencil_modifiers/intern/MOD_gpencilopacity.c  | 60 ++++++++++++++--------
 1 file changed, 40 insertions(+), 20 deletions(-)

(limited to 'source/blender/gpencil_modifiers/intern')

diff --git a/source/blender/gpencil_modifiers/intern/MOD_gpencilopacity.c b/source/blender/gpencil_modifiers/intern/MOD_gpencilopacity.c
index c2ab672b68b..22610771045 100644
--- a/source/blender/gpencil_modifiers/intern/MOD_gpencilopacity.c
+++ b/source/blender/gpencil_modifiers/intern/MOD_gpencilopacity.c
@@ -89,38 +89,56 @@ static void deformStroke(GpencilModifierData *md,
     return;
   }
 
-  if (mmd->modify_color != GP_MODIFY_COLOR_FILL) {
-    gps->runtime.tmp_stroke_rgba[3] *= mmd->factor;
-    /* if factor is > 1, then force opacity */
-    if (mmd->factor > 1.0f) {
-      gps->runtime.tmp_stroke_rgba[3] += mmd->factor - 1.0f;
+  if (mmd->opacity_mode == GP_OPACITY_MODE_MATERIAL) {
+    if (mmd->modify_color != GP_MODIFY_COLOR_FILL) {
+      gps->runtime.tmp_stroke_rgba[3] *= mmd->factor;
+      /* if factor is > 1, then force opacity */
+      if (mmd->factor > 1.0f) {
+        gps->runtime.tmp_stroke_rgba[3] += mmd->factor - 1.0f;
+      }
+      CLAMP(gps->runtime.tmp_stroke_rgba[3], 0.0f, 1.0f);
     }
-    CLAMP(gps->runtime.tmp_stroke_rgba[3], 0.0f, 1.0f);
-  }
 
-  if (mmd->modify_color != GP_MODIFY_COLOR_STROKE) {
-    gps->runtime.tmp_fill_rgba[3] *= mmd->factor;
-    /* if factor is > 1, then force opacity */
-    if (mmd->factor > 1.0f && gps->runtime.tmp_fill_rgba[3] > 1e-5) {
-      gps->runtime.tmp_fill_rgba[3] += mmd->factor - 1.0f;
+    if (mmd->modify_color != GP_MODIFY_COLOR_STROKE) {
+      gps->runtime.tmp_fill_rgba[3] *= mmd->factor;
+      /* if factor is > 1, then force opacity */
+      if (mmd->factor > 1.0f && gps->runtime.tmp_fill_rgba[3] > 1e-5) {
+        gps->runtime.tmp_fill_rgba[3] += mmd->factor - 1.0f;
+      }
+      CLAMP(gps->runtime.tmp_fill_rgba[3], 0.0f, 1.0f);
     }
-    CLAMP(gps->runtime.tmp_fill_rgba[3], 0.0f, 1.0f);
-  }
 
-  /* if opacity > 1.0, affect the strength of the stroke */
-  if (mmd->factor > 1.0f) {
+    /* if opacity > 1.0, affect the strength of the stroke */
+    if (mmd->factor > 1.0f) {
+      for (int i = 0; i < gps->totpoints; i++) {
+        bGPDspoint *pt = &gps->points[i];
+        pt->strength += mmd->factor - 1.0f;
+        CLAMP(pt->strength, 0.0f, 1.0f);
+      }
+    }
+  }
+  /* Apply opacity by strength */
+  else {
     for (int i = 0; i < gps->totpoints; i++) {
       bGPDspoint *pt = &gps->points[i];
       MDeformVert *dvert = gps->dvert != NULL ? &gps->dvert[i] : NULL;
 
       /* verify vertex group */
-      const float weight = get_modifier_point_weight(
+      float weight = get_modifier_point_weight(
           dvert, (mmd->flag & GP_OPACITY_INVERT_VGROUP) != 0, def_nr);
       if (weight < 0.0f) {
+        continue;
+      }
+      if (def_nr < 0) {
         pt->strength += mmd->factor - 1.0f;
       }
       else {
-        pt->strength += (mmd->factor - 1.0f) * weight;
+        /* High factor values, change weight too. */
+        if ((mmd->factor > 1.0f) && (weight < 1.0f)) {
+          weight += mmd->factor - 1.0f;
+          CLAMP(weight, 0.0f, 1.0f);
+        }
+        pt->strength += (mmd->factor - 1) * weight;
       }
       CLAMP(pt->strength, 0.0f, 1.0f);
     }
@@ -152,8 +170,10 @@ static void bakeModifier(Main *bmain, Depsgraph *depsgraph, GpencilModifierData
 
         deformStroke(md, depsgraph, ob, gpl, gpf, gps);
 
-        gpencil_apply_modifier_material(
-            bmain, ob, mat, gh_color, gps, (bool)(mmd->flag & GP_OPACITY_CREATE_COLORS));
+        if (mmd->opacity_mode == GP_OPACITY_MODE_MATERIAL) {
+          gpencil_apply_modifier_material(
+              bmain, ob, mat, gh_color, gps, (bool)(mmd->flag & GP_OPACITY_CREATE_COLORS));
+        }
       }
     }
   }
-- 
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