Fix T59519: Grease Pencil stroke with noise modifier crashes blender

The first point index was wrong calculated.

1 files changed, 4 insertions, 2 deletions

diff --git a/source/blender/gpencil_modifiers/intern/MOD_gpencilnoise.c b/source/blender/gpencil_modifiers/intern/MOD_gpencilnoise.c
index 097b5702721..722cf861fb1 100644
--- a/source/blender/gpencil_modifiers/intern/MOD_gpencilnoise.c
+++ b/source/blender/gpencil_modifiers/intern/MOD_gpencilnoise.c
@@ -147,10 +147,12 @@ static void deformStroke(
 			pt1 = &gps->points[i - 1];
 		}
 		else {
+			int prev_idx = i - 1;
+			CLAMP_MIN(prev_idx, 0);
 			if (gps->dvert) {
-				dvert = &gps->dvert[i - 1];
+				dvert = &gps->dvert[prev_idx];
 			}
-			pt0 = &gps->points[i - 1];
+			pt0 = &gps->points[prev_idx];
 			pt1 = &gps->points[i];
 
 		}