GP: Primitive: Fix jitter

Missing vector calculation.

1 files changed, 17 insertions, 2 deletions

diff --git a/source/blender/editors/gpencil/gpencil_primitive.c b/source/blender/editors/gpencil/gpencil_primitive.c
index d856c1859bb..a2f9de39940 100644
--- a/source/blender/editors/gpencil/gpencil_primitive.c
+++ b/source/blender/editors/gpencil/gpencil_primitive.c
@@ -826,12 +826,27 @@ static void gp_primitive_update_strokes(bContext *C, tGPDprimitive *tgpi)
 			/* exponential value */
 			const float exfactor = SQUARE(brush->gpencil_settings->draw_jitter + 2.0f);
 			const float fac = p2d->rnd[0] * exfactor * jitter;
+
+			/* vector */
+			float mvec[2], svec[2];;
+			if (i > 0) {
+				mvec[0] = (p2d->x - (p2d - 1)->x);
+				mvec[1] = (p2d->y - (p2d - 1)->y);
+				normalize_v2(mvec);
+			}
+			else {
+				zero_v2(mvec);
+			}
+			svec[0] = -mvec[1];
+			svec[1] = mvec[0];
+
 			if (p2d->rnd[0] > 0.5f) {
-				add_v2_fl(&p2d->x, -fac);
+				mul_v2_fl(svec, -fac);
 			}
 			else {
-				add_v2_fl(&p2d->x, fac);
+				mul_v2_fl(svec, fac);
 			}
+			add_v2_v2(&p2d->x, svec);
 		}
 
 		/* apply randomness to pressure */