From 69629ebb1a3d33376aaa3bfcf6fcd385ffa6377b Mon Sep 17 00:00:00 2001
From: Benjamin Otte <otte@redhat.com>
Date: Sun, 2 Jun 2019 15:06:50 +0200
Subject: [PATCH] transform: Treat 0 perspective transforms as identity

This happens if you apply a perspective transform and its inverse, which
is the negative version of the perspective.
---
 gsk/gsktransform.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/gsk/gsktransform.c b/gsk/gsktransform.c
index ac81fe055b..3baf8bb061 100644
--- a/gsk/gsktransform.c
+++ b/gsk/gsktransform.c
@@ -1118,7 +1118,7 @@ gsk_perspective_transform_to_matrix (GskTransform      *transform,
   GskPerspectiveTransform *self = (GskPerspectiveTransform *) transform;
   float f[16] = { 1.f, 0.f, 0.f,  0.f,
                   0.f, 1.f, 0.f,  0.f,
-                  0.f, 0.f, 1.f, -1.f / self->depth,
+                  0.f, 0.f, 1.f, self->depth ? -1.f / self->depth : 0.f,
                   0.f, 0.f, 0.f,  1.f };
 
   graphene_matrix_init_from_float (out_matrix, f);