From da8febb319ff37f20612add7ebc7cc667b81ab4d Mon Sep 17 00:00:00 2001
From: Antonioya <blendergit@gmail.com>
Date: Thu, 3 Jan 2019 10:39:14 +0100
Subject: [PATCH] Fix T59527: Segment fault changing layer visibility and onion
 skin

In some situation when the layer is hidden, the onion skin must be disabled too, because the material is not available.
---
 source/blender/draw/engines/gpencil/gpencil_draw_utils.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/source/blender/draw/engines/gpencil/gpencil_draw_utils.c b/source/blender/draw/engines/gpencil/gpencil_draw_utils.c
index 1275e93744e..fa16a00183e 100644
--- a/source/blender/draw/engines/gpencil/gpencil_draw_utils.c
+++ b/source/blender/draw/engines/gpencil/gpencil_draw_utils.c
@@ -872,6 +872,9 @@ static void gpencil_draw_onion_strokes(
 
 	for (bGPDstroke *gps = gpf->strokes.first; gps; gps = gps->next) {
 		MaterialGPencilStyle *gp_style = BKE_material_gpencil_settings_get(ob, gps->mat_nr + 1);
+		if (gp_style == NULL) {
+			continue;
+		}
 		copy_v4_v4(gps->runtime.tmp_stroke_rgba, gp_style->stroke_rgba);
 		copy_v4_v4(gps->runtime.tmp_fill_rgba, gp_style->fill_rgba);