remove unused dem memory

4 files changed, 22 insertions, 31 deletions

diff --git a/src/mbgl/geometry/dem_data.cpp b/src/mbgl/geometry/dem_data.cpp
index 7fa98950ea..92dd7aee26 100644
--- a/src/mbgl/geometry/dem_data.cpp
+++ b/src/mbgl/geometry/dem_data.cpp
@@ -5,8 +5,8 @@ namespace mbgl {
 
 DEMData::DEMData(const PremultipliedImage& _image, Tileset::DEMEncoding encoding):
     dim(_image.size.height),
-    border(std::max<int32_t>(std::ceil(_image.size.height / 2), 1)),
-    stride(dim + 2 * border),
+    // extra two pixels per row for border backfilling on either edge
+    stride(dim + 2),
     image({ static_cast<uint32_t>(stride), static_cast<uint32_t>(stride) }) {
 
     if (_image.size.height != _image.size.width){
@@ -76,22 +76,16 @@ void DEMData::backfillBorder(const DEMData& borderTileData, int8_t dx, int8_t dy
     // represents. For example, dx = -1, dy = -1 represents the upper left corner of the
     // base tile, so we only need to backfill one pixel at coordinates (-1, -1) of the tile
     // image.
-    int32_t _xMin = dx * dim;
-    int32_t _xMax = dx * dim + dim;
-    int32_t _yMin = dy * dim;
-    int32_t _yMax = dy * dim + dim;
+    int32_t xMin = dx * dim;
+    int32_t xMax = dx * dim + dim;
+    int32_t yMin = dy * dim;
+    int32_t yMax = dy * dim + dim;
     
-    if (dx == -1) _xMin = _xMax - 1;
-    else if (dx == 1) _xMax = _xMin + 1;
+    if (dx == -1) xMin = xMax - 1;
+    else if (dx == 1) xMax = xMin + 1;
     
-    if (dy == -1) _yMin = _yMax - 1;
-    else if (dy == 1) _yMax = _yMin + 1;
-    
-    int32_t xMin = util::clamp(_xMin, -border, dim + border);
-    int32_t xMax = util::clamp(_xMax, -border, dim + border);
-    
-    int32_t yMin = util::clamp(_yMin, -border, dim + border);
-    int32_t yMax = util::clamp(_yMax, -border, dim + border);
+    if (dy == -1) yMin = yMax - 1;
+    else if (dy == 1) yMax = yMin + 1;
     
     int32_t ox = -dx * dim;
     int32_t oy = -dy * dim;
diff --git a/src/mbgl/geometry/dem_data.hpp b/src/mbgl/geometry/dem_data.hpp
index 817d3cc9c9..21146bc468 100644
--- a/src/mbgl/geometry/dem_data.hpp
+++ b/src/mbgl/geometry/dem_data.hpp
@@ -29,7 +29,6 @@ public:
     }
 
     const int32_t dim;
-    const int32_t border;
     const int32_t stride;
 
 
@@ -37,11 +36,11 @@ public:
         PremultipliedImage image;
 
         size_t idx(const int32_t x, const int32_t y) const {
-            assert(x >= -border);
-            assert(x < dim + border);
-            assert(y >= -border);
-            assert(y < dim + border);
-            return (y + border) * stride + (x + border);
+            assert(x >= -1);
+            assert(x < dim + 1);
+            assert(y >= -1);
+            assert(y < dim + 1);
+            return (y + 1) * stride + (x + 1);
         }
 
 };
diff --git a/src/mbgl/renderer/layers/render_hillshade_layer.cpp b/src/mbgl/renderer/layers/render_hillshade_layer.cpp
index 2ee824dcf3..9cdba21c2d 100644
--- a/src/mbgl/renderer/layers/render_hillshade_layer.cpp
+++ b/src/mbgl/renderer/layers/render_hillshade_layer.cpp
@@ -125,8 +125,8 @@ void RenderHillshadeLayer::render(PaintParameters& parameters, RenderSource* src
         }
 
         if (!bucket.isPrepared() && parameters.pass == RenderPass::Pass3D) {
-            const uint16_t tilesize = bucket.getDEMData().dim;
-            OffscreenTexture view(parameters.context, { tilesize, tilesize });
+            const uint16_t stride = bucket.getDEMData().stride;
+            OffscreenTexture view(parameters.context, { stride, stride });
             view.bind();
             
             parameters.context.bindTexture(*bucket.dem, 0, gl::TextureFilter::Nearest, gl::TextureMipMap::No, gl::TextureWrap::Clamp, gl::TextureWrap::Clamp);
@@ -138,7 +138,7 @@ void RenderHillshadeLayer::render(PaintParameters& parameters, RenderSource* src
             const auto allUniformValues = programInstance.computeAllUniformValues(
                 HillshadePrepareProgram::UniformValues {
                     uniforms::u_matrix::Value( mat ),
-                    uniforms::u_dimension::Value( {{uint16_t(tilesize * 2), uint16_t(tilesize * 2)}} ),
+                    uniforms::u_dimension::Value( {{stride, stride}} ),
                     uniforms::u_zoom::Value( float(tile.id.canonical.z) ),
                     uniforms::u_maxzoom::Value( float(maxzoom) ),
                     uniforms::u_image::Value( 0 )
diff --git a/test/geometry/dem_data.test.cpp b/test/geometry/dem_data.test.cpp
index 3848f028f1..bf362820a0 100644
--- a/test/geometry/dem_data.test.cpp
+++ b/test/geometry/dem_data.test.cpp
@@ -20,9 +20,8 @@ TEST(DEMData, ConstructorMapbox) {
     DEMData demdata(image, Tileset::DEMEncoding::Mapbox);
 
     EXPECT_EQ(demdata.dim, 16);
-    EXPECT_EQ(demdata.border, 8);
-    EXPECT_EQ(demdata.stride, 32);
-    EXPECT_EQ(demdata.getImage()->bytes(), size_t(32*32*4));
+    EXPECT_EQ(demdata.stride, 18);
+    EXPECT_EQ(demdata.getImage()->bytes(), size_t(18*18*4));
 };
 
 TEST(DEMData, ConstructorTerrarium) {
@@ -30,9 +29,8 @@ TEST(DEMData, ConstructorTerrarium) {
     DEMData demdata(image, Tileset::DEMEncoding::Terrarium);
 
     EXPECT_EQ(demdata.dim, 16);
-    EXPECT_EQ(demdata.border, 8);
-    EXPECT_EQ(demdata.stride, 32);
-    EXPECT_EQ(demdata.getImage()->bytes(), size_t(32*32*4));
+    EXPECT_EQ(demdata.stride, 18);
+    EXPECT_EQ(demdata.getImage()->bytes(), size_t(18*18*4));
 };
 
 TEST(DEMData, RoundTrip) {