Fix T80191: GPencil - Improve Mesh conversion

There were some problems when converted several objects at the same time, especially with the material conversion. The problems were more visible when bake an animation with several objects at the same time.

* Now the layer name include the object name.
* Reorganize how the materials are generated including object name.
* Fix color not converted to sRGB.
* Avoid triangles when generate the stroke. This fix a draw manager issue and also add more geometry to use later.
* Code cleanup.

1 files changed, 63 insertions, 63 deletions

diff --git a/source/blender/blenkernel/intern/gpencil_geom.c b/source/blender/blenkernel/intern/gpencil_geom.c
index 937741c2ac0..83e3a3098e9 100644
--- a/source/blender/blenkernel/intern/gpencil_geom.c
+++ b/source/blender/blenkernel/intern/gpencil_geom.c
@@ -2252,19 +2252,33 @@ static Material *gpencil_add_material(Main *bmain,
   return mat_gp;
 }
 
-static int gpencil_material_find_index_by_name_prefix(Object *ob, const char *name_prefix)
+static int gpencil_material_find_index_by_name(Object *ob, const char *name)
 {
-  const int name_prefix_len = strlen(name_prefix);
   for (int i = 0; i < ob->totcol; i++) {
     Material *ma = BKE_object_material_get(ob, i + 1);
-    if ((ma != NULL) && (ma->gp_style != NULL) &&
-        (STREQLEN(ma->id.name + 2, name_prefix, name_prefix_len))) {
+    if ((ma != NULL) && (ma->gp_style != NULL) && (STREQ(ma->id.name + 2, name))) {
       return i;
     }
   }
 
   return -1;
 }
+
+/* Create the name with the object name and a subfix. */
+static void make_element_name(char *obname, char *name, const int maxlen, char *r_name)
+{
+  char str[256];
+  sprintf(str, "%s_%s", obname, name);
+  /* Replace any point by underscore. */
+  char *current_pos = strchr(str, '.');
+  while (current_pos) {
+    *current_pos = '_';
+    current_pos = strchr(current_pos, '.');
+  }
+
+  BLI_strncpy_utf8(r_name, str, maxlen);
+}
+
 /**
  * Convert a mesh object to grease pencil stroke.
  *
@@ -2280,9 +2294,8 @@ static int gpencil_material_find_index_by_name_prefix(Object *ob, const char *na
  * \param frame_offset: Destination frame number offset.
  * \param use_seams: Only export seam edges.
  * \param use_faces: Export faces as filled strokes.
- * \simple_material: Create only 2 materials (stroke and fill)
  */
-void BKE_gpencil_convert_mesh(Main *bmain,
+bool BKE_gpencil_convert_mesh(Main *bmain,
                               Depsgraph *depsgraph,
                               Scene *scene,
                               Object *ob_gp,
@@ -2293,11 +2306,10 @@ void BKE_gpencil_convert_mesh(Main *bmain,
                               const float matrix[4][4],
                               const int frame_offset,
                               const bool use_seams,
-                              const bool use_faces,
-                              const bool simple_material)
+                              const bool use_faces)
 {
   if (ELEM(NULL, ob_gp, ob_mesh) || (ob_gp->type != OB_GPENCIL) || (ob_gp->data == NULL)) {
-    return;
+    return false;
   }
 
   bGPdata *gpd = (bGPdata *)ob_gp->data;
@@ -2308,77 +2320,56 @@ void BKE_gpencil_convert_mesh(Main *bmain,
   MPoly *mp, *mpoly = me_eval->mpoly;
   MLoop *mloop = me_eval->mloop;
   int mpoly_len = me_eval->totpoly;
-  int stroke_mat_index = gpencil_material_find_index_by_name_prefix(ob_gp, "Stroke");
-  int fill_mat_index = gpencil_material_find_index_by_name_prefix(ob_gp, "Fill");
-
-  /* If the object has enough materials means it was created in a previous step. */
-  const bool create_mat = ((ob_gp->totcol > 0) && (ob_gp->totcol >= ob_mesh->totcol)) ? false :
-                                                                                        true;
+  char element_name[200];
 
   /* Need at least an edge. */
   if (me_eval->totvert < 2) {
-    return;
+    return false;
   }
 
-  int r_idx;
   const float default_colors[2][4] = {{0.0f, 0.0f, 0.0f, 1.0f}, {0.7f, 0.7f, 0.7f, 1.0f}};
   /* Create stroke material. */
-  if (create_mat) {
-    if (stroke_mat_index == -1) {
-      gpencil_add_material(bmain, ob_gp, "Stroke", default_colors[0], true, false, &r_idx);
-      stroke_mat_index = ob_gp->totcol - 1;
-    }
+  make_element_name(ob_mesh->id.name + 2, "Stroke", 64, element_name);
+  int stroke_mat_index = gpencil_material_find_index_by_name(ob_gp, element_name);
+
+  if (stroke_mat_index == -1) {
+    gpencil_add_material(
+        bmain, ob_gp, element_name, default_colors[0], true, false, &stroke_mat_index);
   }
+
   /* Export faces as filled strokes. */
   if (use_faces) {
-    if (create_mat) {
-      /* Find a material slot with material assigned. */
-      bool material_found = false;
-      for (int i = 0; i < ob_mesh->totcol; i++) {
-        Material *ma = BKE_object_material_get(ob_mesh, i + 1);
-        if (ma != NULL) {
-          material_found = true;
-          break;
-        }
-      }
-
-      /* If no materials or use simple materials, create a simple fill. */
-      if ((!material_found) || (simple_material)) {
-        if (fill_mat_index == -1) {
-          gpencil_add_material(bmain, ob_gp, "Fill", default_colors[1], false, true, &r_idx);
-          fill_mat_index = ob_gp->totcol - 1;
-        }
-      }
-      else {
-        /* Create all materials for fill. */
-        for (int i = 0; i < ob_mesh->totcol; i++) {
-          Material *ma = BKE_object_material_get(ob_mesh, i + 1);
-          if (ma == NULL) {
-            continue;
-          }
-          float color[4];
-          copy_v3_v3(color, &ma->r);
-          color[3] = 1.0f;
-          gpencil_add_material(bmain, ob_gp, ma->id.name + 2, color, false, true, &r_idx);
-        }
-      }
-    }
 
     /* Read all polygons and create fill for each. */
     if (mpoly_len > 0) {
-      bGPDlayer *gpl_fill = BKE_gpencil_layer_named_get(gpd, DATA_("Fills"));
+      make_element_name(ob_mesh->id.name + 2, "Fills", 128, element_name);
+      /* Create Layer and Frame. */
+      bGPDlayer *gpl_fill = BKE_gpencil_layer_named_get(gpd, element_name);
       if (gpl_fill == NULL) {
-        gpl_fill = BKE_gpencil_layer_addnew(gpd, DATA_("Fills"), true);
+        gpl_fill = BKE_gpencil_layer_addnew(gpd, element_name, true);
       }
       bGPDframe *gpf_fill = BKE_gpencil_layer_frame_get(
           gpl_fill, CFRA + frame_offset, GP_GETFRAME_ADD_NEW);
       int i;
       for (i = 0, mp = mpoly; i < mpoly_len; i++, mp++) {
         MLoop *ml = &mloop[mp->loopstart];
-        /* Create fill stroke. */
-        int mat_idx = (simple_material) || (mp->mat_nr + 1 > ob_gp->totcol - 1) ?
-                          MAX2(fill_mat_index, 0) :
-                          mp->mat_nr + 1;
+        /* Find material. */
+        int mat_idx = 0;
+        Material *ma = BKE_object_material_get(ob_mesh, mp->mat_nr + 1);
+        make_element_name(
+            ob_mesh->id.name + 2, (ma != NULL) ? ma->id.name + 2 : "Fill", 64, element_name);
+        mat_idx = gpencil_material_find_index_by_name(ob_gp, element_name);
+        if (mat_idx == -1) {
+          float color[4];
+          if (ma != NULL) {
+            copy_v3_v3(color, &ma->r);
+            color[3] = 1.0f;
+          }
+          else {
+            copy_v4_v4(color, default_colors[1]);
+          }
+          gpencil_add_material(bmain, ob_gp, element_name, color, false, true, &mat_idx);
+        }
 
         bGPDstroke *gps_fill = BKE_gpencil_stroke_add(gpf_fill, mat_idx, mp->totloop, 10, false);
         gps_fill->flag |= GP_STROKE_CYCLIC;
@@ -2386,13 +2377,16 @@ void BKE_gpencil_convert_mesh(Main *bmain,
         /* Add points to strokes. */
         for (int j = 0; j < mp->totloop; j++, ml++) {
           MVert *mv = &me_eval->mvert[ml->v];
-
           bGPDspoint *pt = &gps_fill->points[j];
           copy_v3_v3(&pt->x, mv->co);
           mul_m4_v3(matrix, &pt->x);
           pt->pressure = 1.0f;
           pt->strength = 1.0f;
         }
+        /* If has only 3 points subdivide. */
+        if (mp->totloop == 3) {
+          BKE_gpencil_stroke_subdivide(gps_fill, 1, GP_SUBDIV_SIMPLE);
+        }
 
         BKE_gpencil_stroke_geometry_update(gps_fill);
       }
@@ -2400,17 +2394,23 @@ void BKE_gpencil_convert_mesh(Main *bmain,
   }
 
   /* Create stroke from edges. */
-  bGPDlayer *gpl_stroke = BKE_gpencil_layer_named_get(gpd, DATA_("Lines"));
+  make_element_name(ob_mesh->id.name + 2, "Lines", 128, element_name);
+
+  /* Create Layer and Frame. */
+  bGPDlayer *gpl_stroke = BKE_gpencil_layer_named_get(gpd, element_name);
   if (gpl_stroke == NULL) {
-    gpl_stroke = BKE_gpencil_layer_addnew(gpd, DATA_("Lines"), true);
+    gpl_stroke = BKE_gpencil_layer_addnew(gpd, element_name, true);
   }
   bGPDframe *gpf_stroke = BKE_gpencil_layer_frame_get(
       gpl_stroke, CFRA + frame_offset, GP_GETFRAME_ADD_NEW);
+
   gpencil_generate_edgeloops(
       ob_eval, gpf_stroke, stroke_mat_index, angle, thickness, offset, matrix, use_seams);
 
   /* Tag for recalculation */
   DEG_id_tag_update(&gpd->id, ID_RECALC_GEOMETRY | ID_RECALC_COPY_ON_WRITE);
+
+  return true;
 }
 
 /**