implement functions for background-image

3 files changed, 36 insertions, 18 deletions

diff --git a/src/mbgl/renderer/painter.cpp b/src/mbgl/renderer/painter.cpp
index 448b380743..f8347123c0 100644
--- a/src/mbgl/renderer/painter.cpp
+++ b/src/mbgl/renderer/painter.cpp
@@ -376,39 +376,57 @@ void Painter::renderTileLayer(const Tile& tile, util::ptr<StyleLayer> layer_desc
 void Painter::renderBackground(util::ptr<StyleLayer> layer_desc) {
     const BackgroundProperties& properties = layer_desc->getProperties<BackgroundProperties>();
 
-    if (properties.image.size()) {
+    if (properties.image.low.size()) {
         if ((properties.opacity >= 1.0f) != (pass == RenderPass::Opaque))
             return;
 
-        SpriteAtlasPosition imagePos = spriteAtlas.getPosition(properties.image, true);
+        SpriteAtlasPosition imagePosA = spriteAtlas.getPosition(properties.image.low, true);
+        SpriteAtlasPosition imagePosB = spriteAtlas.getPosition(properties.image.high, true);
         float zoomFraction = state.getZoomFraction();
 
         useProgram(patternShader->program);
         patternShader->u_matrix = identityMatrix;
-        patternShader->u_pattern_tl_a = imagePos.tl;
-        patternShader->u_pattern_br_a = imagePos.br;
+        patternShader->u_pattern_tl_a = imagePosA.tl;
+        patternShader->u_pattern_br_a = imagePosA.br;
+        patternShader->u_pattern_tl_b = imagePosB.tl;
+        patternShader->u_pattern_br_b = imagePosB.br;
         patternShader->u_mix = zoomFraction;
         patternShader->u_opacity = properties.opacity;
 
-        std::array<float, 2> size = imagePos.size;
         double lon, lat;
         state.getLonLat(lon, lat);
         std::array<float, 2> center = state.locationCoordinate(lon, lat);
         float scale = 1 / std::pow(2, zoomFraction);
 
-        mat3 matrix;
-        matrix::identity(matrix);
-        matrix::scale(matrix, matrix,
-                      1.0f / size[0],
-                      1.0f / size[1]);
-        matrix::translate(matrix, matrix,
-                          std::fmod(center[0] * 512, size[0]),
-                          std::fmod(center[1] * 512, size[1]));
-        matrix::rotate(matrix, matrix, -state.getAngle());
-        matrix::scale(matrix, matrix,
+        std::array<float, 2> sizeA = imagePosA.size;
+        mat3 matrixA;
+        matrix::identity(matrixA);
+        matrix::scale(matrixA, matrixA,
+                      1.0f / (sizeA[0] * properties.image.lowScale),
+                      1.0f / (sizeA[1] * properties.image.lowScale));
+        matrix::translate(matrixA, matrixA,
+                          std::fmod(center[0] * 512, sizeA[0] * properties.image.lowScale),
+                          std::fmod(center[1] * 512, sizeA[1] * properties.image.lowScale));
+        matrix::rotate(matrixA, matrixA, -state.getAngle());
+        matrix::scale(matrixA, matrixA,
                        scale * state.getWidth()  / 2,
                       -scale * state.getHeight() / 2);
-        patternShader->u_patternmatrix_a = matrix;
+
+        std::array<float, 2> sizeB = imagePosB.size;
+        mat3 matrixB;
+        matrix::identity(matrixB);
+        matrix::scale(matrixB, matrixB,
+                      1.0f / (sizeB[0] * properties.image.highScale),
+                      1.0f / (sizeB[1] * properties.image.highScale));
+        matrix::translate(matrixB, matrixB,
+                          std::fmod(center[0] * 512, sizeB[0] * properties.image.highScale),
+                          std::fmod(center[1] * 512, sizeB[1] * properties.image.highScale));
+        matrix::rotate(matrixB, matrixB, -state.getAngle());
+        matrix::scale(matrixB, matrixB,
+                       scale * state.getWidth()  / 2,
+                      -scale * state.getHeight() / 2);
+
+        patternShader->u_patternmatrix_a = matrixA;
 
         backgroundBuffer.bind();
         patternShader->bind(0);
diff --git a/src/mbgl/style/style_parser.cpp b/src/mbgl/style/style_parser.cpp
index 3f1fc64dab..1cf8d2e355 100644
--- a/src/mbgl/style/style_parser.cpp
+++ b/src/mbgl/style/style_parser.cpp
@@ -703,7 +703,7 @@ void StyleParser::parsePaint(JSVal value, ClassProperties &klass) {
 
     parseOptionalProperty<Function<float>>("background-opacity", Key::BackgroundOpacity, klass, value);
     parseOptionalProperty<Function<Color>>("background-color", Key::BackgroundColor, klass, value);
-    parseOptionalProperty<std::string>("background-image", Key::BackgroundImage, klass, value);
+    parseOptionalProperty<FadedStopsFunction<Faded<std::string>>>("background-image", Key::BackgroundImage, klass, value);
 }
 
 void StyleParser::parseReference(JSVal value, util::ptr<StyleLayer> &layer) {
diff --git a/src/mbgl/style/style_properties.hpp b/src/mbgl/style/style_properties.hpp
index db9e4c34c9..d2c134e8d8 100644
--- a/src/mbgl/style/style_properties.hpp
+++ b/src/mbgl/style/style_properties.hpp
@@ -96,7 +96,7 @@ struct BackgroundProperties {
     inline BackgroundProperties() {}
     float opacity = 1.0f;
     Color color = {{ 0, 0, 0, 1 }};
-    std::string image;
+    Faded<std::string> image;
 };
 
 typedef mapbox::util::variant<