[gtk] gl renderer: Pass correct matrix category when rendering offscreen

[Timm Bäder <baedert src gnome org>]

commit aa922f0779d7bc6d988383b39bd4c4c3157ad4d5
Author: Timm Bäder <mail baedert org>
Date:   Mon May 20 12:10:12 2019 +0200

    gl renderer: Pass correct matrix category when rendering offscreen
    
    We can't just pretend we have an identity matrix when we are actually
    scaling. This fixes the node editor sometimes not drawing things when
    rendering to a texture. We were mistakenly discaring render nodes
    because the bounds transformation was wrong.

 gsk/gl/gskglrenderer.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)
---
diff --git a/gsk/gl/gskglrenderer.c b/gsk/gl/gskglrenderer.c
index 95310adfed..1a9f20bf02 100644
--- a/gsk/gl/gskglrenderer.c
+++ b/gsk/gl/gskglrenderer.c
@@ -2707,7 +2707,7 @@ add_offscreen_ops (GskGLRenderer         *self,
   int render_target;
   int prev_render_target;
   RenderOp op;
-  graphene_matrix_t identity;
+  graphene_matrix_t modelview;
   graphene_matrix_t prev_projection;
   graphene_rect_t prev_viewport;
   graphene_matrix_t item_proj;
@@ -2762,15 +2762,16 @@ add_offscreen_ops (GskGLRenderer         *self,
                               (bounds->origin.y + bounds->size.height) * scale,
                               ORTHO_NEAR_PLANE, ORTHO_FAR_PLANE);
   graphene_matrix_scale (&item_proj, 1, -1, 1);
-  graphene_matrix_init_identity (&identity);
-  graphene_matrix_scale (&identity, scale, scale, 1);
+  graphene_matrix_init_scale (&modelview, scale, scale, 1);
 
   prev_render_target = ops_set_render_target (builder, render_target);
   /* Clear since we use this rendertarget for the first time */
   op.op = OP_CLEAR;
   ops_add (builder, &op);
   prev_projection = ops_set_projection (builder, &item_proj);
-  ops_set_modelview (builder, &identity, GSK_TRANSFORM_CATEGORY_IDENTITY);
+  ops_set_modelview (builder, &modelview,
+                     G_APPROX_VALUE (scale, 1.0, 0.01f) ? GSK_TRANSFORM_CATEGORY_IDENTITY :
+                                                          GSK_TRANSFORM_CATEGORY_2D_AFFINE);
   prev_viewport = ops_set_viewport (builder,
                                     &GRAPHENE_RECT_INIT (bounds->origin.x * scale,
                                                          bounds->origin.y * scale,