background grid

include/llmr/map/source.hpp

@@ -37,6 +37,7 @@ public:
 
     bool update();
     void updateMatrices(const TransformState &transform);
+    bool viewportTileParsed();
     void drawClippingMasks();
     size_t getTileCount() const;
     void render(const LayerDescription& layer_desc, const BucketDescription &bucket_desc);

src/map/source.cpp

@@ -57,6 +57,19 @@ size_t Source::getTileCount() const {
     return tiles.size();
 }
 
+bool Source::viewportTileParsed() {
+    bool parsed = false;
+
+    for (auto &pair : tiles) {
+        Tile::ID id = pair.first;
+        if (hasTile(id) == TileData::State::parsed) {
+            parsed = true;
+        }
+    }
+
+    return parsed;
+}
+
 void Source::drawClippingMasks() {
     for (std::pair<const Tile::ID, std::unique_ptr<Tile>> &pair : tiles) {
         Tile &tile = *pair.second;

src/renderer/painter_clipping.cpp

@@ -9,22 +9,64 @@ using namespace llmr;
 void Painter::drawClippingMasks(const Sources &sources) {
     gl::group group("clipping masks");
 
-    useProgram(plainShader->program);
     glDisable(GL_DEPTH_TEST);
     depthMask(false);
     glDepthRange(1.0f, 1.0f);
     glStencilMask(0xFF);
 
-    const BackgroundProperties &properties = map.getStyle()->computed.background;
-    Color background = properties.color;
-    const float opacity = properties.opacity;
-    background[0] *= opacity;
-    background[1] *= opacity;
-    background[2] *= opacity;
-    background[3] *= opacity;
-    plainShader->setColor(background);
+    bool ready = false;
 
-    coveringPlainArray.bind(*plainShader, tileStencilBuffer, BUFFER_OFFSET(0));
+    for (const auto &pair : sources) {
+        Source &source = *pair.second;
+        if (source.viewportTileParsed()) {
+            ready = true;
+        }
+    }
+
+    if (ready) {
+        // At least one viewport tile is parsed. Draw the background.
+        useProgram(plainShader->program);
+
+        const BackgroundProperties &properties = map.getStyle()->computed.background;
+        Color background = properties.color;
+        const float opacity = properties.opacity;
+        background[0] *= opacity;
+        background[1] *= opacity;
+        background[2] *= opacity;
+        background[3] *= opacity;
+        plainShader->setColor(background);
+
+        coveringPlainArray.bind(*plainShader, tileStencilBuffer, BUFFER_OFFSET(0));
+    } else {
+        // No viewport tiles are parsed. Draw the grid pattern.
+        const std::shared_ptr<Sprite> &sprite = map.getStyle()->sprite;
+        if (sprite) {
+            SpriteAtlas &spriteAtlas = *map.getSpriteAtlas();
+            Rect<uint16_t> imagePos = spriteAtlas.getImage("matte-256", *sprite);
+
+            std::array<float, 2> imageSize = {{
+                    (float)(imagePos.w * 0.5),
+                    (float)(imagePos.h * 0.5)
+                }
+            };
+
+            useProgram(patternShader->program);
+            patternShader->setPatternSize(imageSize);
+            patternShader->setPatternTopLeft({{
+                float(imagePos.x) / spriteAtlas.getWidth(),
+                float(imagePos.y) / spriteAtlas.getHeight(),
+            }});
+            patternShader->setPatternBottomRight({{
+                float(imagePos.x + imagePos.w) / spriteAtlas.getWidth(),
+                float(imagePos.y + imagePos.h) / spriteAtlas.getHeight(),
+            }});
+            std::array<float, 4> color = {{ 1, 1, 1, 1 }};
+            patternShader->setColor(color);
+            spriteAtlas.bind(true);
+
+            coveringPatternArray.bind(*patternShader, tileStencilBuffer, BUFFER_OFFSET(0));
+        }
+    }
 
     for (const auto &pair : sources) {
         Source &source = *pair.second;