From 8b27aba0c412b129a379101c00450819d3835ef4 Mon Sep 17 00:00:00 2001
From: Jiri Drbalek <jiri.drbalek@firma.seznam.cz>
Date: Mon, 6 Aug 2018 18:14:07 +0200
Subject: [PATCH 1/2] Fix seams of mesh faces when warping transparent raster

---
 src/warp.cpp | 33 +++++++++++++++++++++++++++++++--
 1 file changed, 31 insertions(+), 2 deletions(-)

diff --git a/src/warp.cpp b/src/warp.cpp
index 58f0fbeee..b066bbfd1 100644
--- a/src/warp.cpp
+++ b/src/warp.cpp
@@ -51,6 +51,34 @@
 
 namespace mapnik {
 
+template <typename T>
+struct pixel_format
+{
+    using type = typename detail::agg_scaling_traits<T>::pixfmt_pre;
+};
+
+template <>
+struct pixel_format<image_rgba8>
+{
+    struct src_blender
+    {
+        using color_type = agg::rgba8;
+        using order_type = agg::order_rgba;
+        using value_type = typename color_type::value_type;
+
+        static inline void blend_pix(unsigned /*op*/, value_type* p,
+                                     unsigned cr, unsigned cg, unsigned cb,
+                                     unsigned ca,
+                                     unsigned cover)
+        {
+            agg::comp_op_rgba_src<color_type, order_type>::blend_pix(p, cr, cg, cb, ca, cover);
+        }
+    };
+
+    // Use comp_op_src to fix seams between faces of the mesh
+    using type = agg::pixfmt_custom_blend_rgba<src_blender, agg::rendering_buffer>;
+};
+
 template <typename T>
 MAPNIK_DECL void warp_image (T & target, T const& source, proj_transform const& prj_trans,
                  box2d<double> const& target_ext, box2d<double> const& source_ext,
@@ -61,7 +89,8 @@ MAPNIK_DECL void warp_image (T & target, T const& source, proj_transform const&
     using pixel_type = typename image_type::pixel_type;
     using pixfmt_pre = typename detail::agg_scaling_traits<image_type>::pixfmt_pre;
     using color_type = typename detail::agg_scaling_traits<image_type>::color_type;
-    using renderer_base = agg::renderer_base<pixfmt_pre>;
+    using output_pixfmt_type = typename pixel_format<T>::type;
+    using renderer_base = agg::renderer_base<output_pixfmt_type>;
     using interpolator_type = typename detail::agg_scaling_traits<image_type>::interpolator_type;
 
     constexpr std::size_t pixel_size = sizeof(pixel_type);
@@ -95,7 +124,7 @@ MAPNIK_DECL void warp_image (T & target, T const& source, proj_transform const&
                               target.width(),
                               target.height(),
                               target.width() * pixel_size);
-    pixfmt_pre pixf(buf);
+    output_pixfmt_type pixf(buf);
     renderer_base rb(pixf);
     rasterizer.clip_box(0, 0, target.width(), target.height());
     agg::rendering_buffer buf_tile(

From b50498cb535b4bbb9ee588917373cfcca1ddf1be Mon Sep 17 00:00:00 2001
From: Jiri Drbalek <jiri.drbalek@firma.seznam.cz>
Date: Tue, 7 Aug 2018 11:58:24 +0000
Subject: [PATCH 2/2] Update test data

---
 test/data        | 2 +-
 test/data-visual | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/test/data b/test/data
index 049658fa1..9cf6c17c9 160000
--- a/test/data
+++ b/test/data
@@ -1 +1 @@
-Subproject commit 049658fa104f368f78c3e8d9bddd50719492bcd5
+Subproject commit 9cf6c17c9ecf9fa970c4f13d8b481817a2cb8015
diff --git a/test/data-visual b/test/data-visual
index bbeb5ec35..263360fae 160000
--- a/test/data-visual
+++ b/test/data-visual
@@ -1 +1 @@
-Subproject commit bbeb5ec35c75fa8b5712f8215f132a19e84ea1fb
+Subproject commit 263360fae07cceee0fbdb7fa213ae76f3977c567