[general] moving ios and android project under ./platform folder

src/mbgl/programs/background_program.cpp

@@ -0,0 +1,45 @@
+#include <mbgl/programs/background_program.hpp>
+#include <mbgl/renderer/image_atlas.hpp>
+#include <mbgl/renderer/cross_faded_property_evaluator.hpp>
+#include <mbgl/tile/tile_id.hpp>
+#include <mbgl/map/transform_state.hpp>
+
+namespace mbgl {
+
+using namespace style;
+
+static_assert(sizeof(BackgroundLayoutVertex) == 4, "expected BackgroundLayoutVertex size");
+
+BackgroundPatternProgram::LayoutUniformValues
+BackgroundPatternProgram::layoutUniformValues(mat4 matrix,
+                                              float opacity,
+                                              Size atlasSize,
+                                              const ImagePosition& a,
+                                              const ImagePosition& b,
+                                              const CrossfadeParameters& fading,
+                                              const UnwrappedTileID& tileID,
+                                              const TransformState& state) {
+    int32_t tileSizeAtNearestZoom = util::tileSize * state.zoomScale(state.getIntegerZoom() - tileID.canonical.z);
+    int32_t pixelX = tileSizeAtNearestZoom * (tileID.canonical.x + tileID.wrap * state.zoomScale(tileID.canonical.z));
+    int32_t pixelY = tileSizeAtNearestZoom * tileID.canonical.y;
+
+    return {
+        uniforms::matrix::Value( matrix ),
+        uniforms::opacity::Value( opacity ),
+        uniforms::texsize::Value( atlasSize ),
+        uniforms::pattern_tl_a::Value( a.tl() ),
+        uniforms::pattern_br_a::Value( a.br() ),
+        uniforms::pattern_tl_b::Value( b.tl() ),
+        uniforms::pattern_br_b::Value( b.br() ),
+        uniforms::pattern_size_a::Value( a.displaySize() ),
+        uniforms::pattern_size_b::Value( b.displaySize() ),
+        uniforms::scale_a::Value( fading.fromScale ),
+        uniforms::scale_b::Value( fading.toScale ),
+        uniforms::mix::Value( fading.t ),
+        uniforms::pixel_coord_upper::Value( std::array<float, 2> {{ float(pixelX >> 16), float(pixelY >> 16) }}),
+        uniforms::pixel_coord_lower::Value( std::array<float, 2> {{ float(pixelX & 0xFFFF), float(pixelY & 0xFFFF)}}),
+        uniforms::tile_units_to_pixels::Value( 1.0f / tileID.pixelsToTileUnits(1.0f, state.getIntegerZoom()) ),
+    };
+}
+
+} // namespace mbgl