upload all GL objects before rendering a frame

This moves all texture updates and buffer uploads to the beginning of every frame, before we issue any drawing commands. This means the GPU typically has much more time to upload the data in the background until we actually need it, and doesn't have to pause to store/load the framebuffer.

7 files changed, 34 insertions, 2 deletions

diff --git a/src/mbgl/geometry/buffer.hpp b/src/mbgl/geometry/buffer.hpp
index 01af5df18e..7e3ced4424 100644
--- a/src/mbgl/geometry/buffer.hpp
+++ b/src/mbgl/geometry/buffer.hpp
@@ -67,6 +67,7 @@ public:
         return buffer;
     }
 
+    // Uploads the buffer to the GPU to be available when we need it.
     inline void upload() {
         if (!buffer) {
             bind();
diff --git a/src/mbgl/geometry/glyph_atlas.cpp b/src/mbgl/geometry/glyph_atlas.cpp
index f690004b52..378664f303 100644
--- a/src/mbgl/geometry/glyph_atlas.cpp
+++ b/src/mbgl/geometry/glyph_atlas.cpp
@@ -140,6 +140,12 @@ void GlyphAtlas::removeGlyphs(uintptr_t tileUID) {
     }
 }
 
+void GlyphAtlas::upload() {
+    if (dirty) {
+        bind();
+    }
+}
+
 void GlyphAtlas::bind() {
     if (!texture) {
         MBGL_CHECK_ERROR(glGenTextures(1, &texture));
diff --git a/src/mbgl/geometry/glyph_atlas.hpp b/src/mbgl/geometry/glyph_atlas.hpp
index a25c735a8e..dfa568f0fd 100644
--- a/src/mbgl/geometry/glyph_atlas.hpp
+++ b/src/mbgl/geometry/glyph_atlas.hpp
@@ -24,8 +24,13 @@ public:
                    GlyphPositions&);
     void removeGlyphs(uintptr_t tileUID);
 
+    // Binds the atlas texture to the GPU, and uploads data if it is out of date.
     void bind();
 
+    // Uploads the texture to the GPU to be available when we need it. This is a lazy operation;
+    // the texture is only bound when the data is out of date (=dirty).
+    void upload();
+
     const uint16_t width = 0;
     const uint16_t height = 0;
 
diff --git a/src/mbgl/geometry/line_atlas.cpp b/src/mbgl/geometry/line_atlas.cpp
index f64989d661..0dcaab2c45 100644
--- a/src/mbgl/geometry/line_atlas.cpp
+++ b/src/mbgl/geometry/line_atlas.cpp
@@ -129,6 +129,12 @@ LinePatternPos LineAtlas::addDash(const std::vector<float> &dasharray, bool roun
     return position;
 };
 
+void LineAtlas::upload() {
+    if (dirty) {
+        bind();
+    }
+}
+
 void LineAtlas::bind() {
     std::lock_guard<std::recursive_mutex> lock(mtx);
 
diff --git a/src/mbgl/geometry/line_atlas.hpp b/src/mbgl/geometry/line_atlas.hpp
index df60a2dec5..3683272f98 100644
--- a/src/mbgl/geometry/line_atlas.hpp
+++ b/src/mbgl/geometry/line_atlas.hpp
@@ -19,8 +19,13 @@ public:
     LineAtlas(uint16_t width, uint16_t height);
     ~LineAtlas();
 
+    // Binds the atlas texture to the GPU, and uploads data if it is out of date.
     void bind();
 
+    // Uploads the texture to the GPU to be available when we need it. This is a lazy operation;
+    // the texture is only bound when the data is out of date (=dirty).
+    void upload();
+
     LinePatternPos getDashPosition(const std::vector<float>&, bool);
     LinePatternPos addDash(const std::vector<float> &dasharray, bool round);
 
diff --git a/src/mbgl/geometry/sprite_atlas.cpp b/src/mbgl/geometry/sprite_atlas.cpp
index c2686e2f34..a6156febbc 100644
--- a/src/mbgl/geometry/sprite_atlas.cpp
+++ b/src/mbgl/geometry/sprite_atlas.cpp
@@ -230,6 +230,12 @@ void SpriteAtlas::setSprite(util::ptr<Sprite> sprite_) {
     });
 }
 
+void SpriteAtlas::upload() {
+    if (dirty) {
+        bind();
+    }
+}
+
 void SpriteAtlas::bind(bool linear) {
     bool first = false;
     if (!texture) {
diff --git a/src/mbgl/geometry/sprite_atlas.hpp b/src/mbgl/geometry/sprite_atlas.hpp
index 079c15cefd..5605143104 100644
--- a/src/mbgl/geometry/sprite_atlas.hpp
+++ b/src/mbgl/geometry/sprite_atlas.hpp
@@ -50,10 +50,13 @@ public:
 
     SpriteAtlasPosition getPosition(const std::string& name, bool repeating = false);
 
-    // Binds the image buffer of this sprite atlas to the GPU, and uploads data if it is out
-    // of date.
+    // Binds the atlas texture to the GPU, and uploads data if it is out of date.
     void bind(bool linear = false);
 
+    // Uploads the texture to the GPU to be available when we need it. This is a lazy operation;
+    // the texture is only bound when the data is out of date (=dirty).
+    void upload();
+
     inline float getWidth() const { return width; }
     inline float getHeight() const { return height; }
     inline float getTextureWidth() const { return width * pixelRatio; }