From 93cfca4d4e3294e777d0654d5b7812a35a9ab064 Mon Sep 17 00:00:00 2001
From: Bruno de Oliveira Abinader <bruno@mapbox.com>
Date: Sun, 14 Feb 2016 22:31:50 +0200
Subject: [PATCH] [gl] Added mbgl::gl::VAOHolder

---
 src/mbgl/geometry/vao.cpp       | 16 +++-------------
 src/mbgl/geometry/vao.hpp       | 10 ++++++----
 src/mbgl/gl/gl_object_store.cpp | 29 ++++++++++++++++-------------
 src/mbgl/gl/gl_object_store.hpp | 16 ++++++++++++++--
 4 files changed, 39 insertions(+), 32 deletions(-)

diff --git a/src/mbgl/geometry/vao.cpp b/src/mbgl/geometry/vao.cpp
index db4d23388..964ac31a2 100644
--- a/src/mbgl/geometry/vao.cpp
+++ b/src/mbgl/geometry/vao.cpp
@@ -11,19 +11,11 @@ void VertexArrayObject::Unbind() {
     MBGL_CHECK_ERROR(gl::BindVertexArray(0));
 }
 
-void VertexArrayObject::Delete(GLsizei n, const GLuint* arrays) {
-    if (!gl::DeleteVertexArrays) return;
-    MBGL_CHECK_ERROR(gl::DeleteVertexArrays(n, arrays));
-}
-
 VertexArrayObject::VertexArrayObject() {
 }
 
 VertexArrayObject::~VertexArrayObject() {
-    if (!gl::DeleteVertexArrays) return;
-    if (vao) {
-        util::ThreadContext::getGLObjectStore()->abandonVAO(vao);
-    }
+    if (vao) util::ThreadContext::getGLObjectStore()->abandon(std::move(vao));
 }
 
 void VertexArrayObject::bindVertexArrayObject() {
@@ -36,10 +28,8 @@ void VertexArrayObject::bindVertexArrayObject() {
         return;
     }
 
-    if (!vao) {
-        MBGL_CHECK_ERROR(gl::GenVertexArrays(1, &vao));
-    }
-    MBGL_CHECK_ERROR(gl::BindVertexArray(vao));
+    if (!vao) vao.create();
+    MBGL_CHECK_ERROR(gl::BindVertexArray(vao.getID()));
 }
 
 void VertexArrayObject::verifyBinding(Shader &shader, GLuint vertexBuffer, GLuint elementsBuffer,
diff --git a/src/mbgl/geometry/vao.hpp b/src/mbgl/geometry/vao.hpp
index 1b3f43806..cab258cb5 100644
--- a/src/mbgl/geometry/vao.hpp
+++ b/src/mbgl/geometry/vao.hpp
@@ -3,16 +3,18 @@
 
 #include <mbgl/shader/shader.hpp>
 #include <mbgl/gl/gl.hpp>
+#include <mbgl/gl/gl_object_store.hpp>
 #include <mbgl/util/noncopyable.hpp>
 
 #include <stdexcept>
 
 namespace mbgl {
 
+class Shader;
+
 class VertexArrayObject : public util::noncopyable {
 public:
     static void Unbind();
-    static void Delete(GLsizei n, const GLuint* arrays);
 
     VertexArrayObject();
     ~VertexArrayObject();
@@ -46,8 +48,8 @@ public:
         }
     }
 
-    inline GLuint getID() const {
-        return vao;
+    GLuint getID() const {
+        return vao.getID();
     }
 
 private:
@@ -55,7 +57,7 @@ private:
     void storeBinding(Shader &shader, GLuint vertexBuffer, GLuint elementsBuffer, GLbyte *offset);
     void verifyBinding(Shader &shader, GLuint vertexBuffer, GLuint elementsBuffer, GLbyte *offset);
 
-    GLuint vao = 0;
+    gl::VAOHolder vao;
 
     // For debug reasons, we're storing the bind information so that we can
     // detect errors and report
diff --git a/src/mbgl/gl/gl_object_store.cpp b/src/mbgl/gl/gl_object_store.cpp
index addf1cc97..62d92f310 100644
--- a/src/mbgl/gl/gl_object_store.cpp
+++ b/src/mbgl/gl/gl_object_store.cpp
@@ -1,8 +1,5 @@
 #include <mbgl/gl/gl_object_store.hpp>
 #include <mbgl/util/thread_context.hpp>
-#include <mbgl/util/thread.hpp>
-#include <mbgl/geometry/vao.hpp>
-#include <mbgl/gl/gl.hpp>
 
 #include <cassert>
 
@@ -74,10 +71,17 @@ void TexturePoolHolder::reset() {
     ids.fill(0);
 }
 
-
-void GLObjectStore::abandonVAO(GLuint vao) {
+void VAOHolder::create() {
+    if (id) return;
     assert(util::ThreadContext::currentlyOn(util::ThreadType::Map));
-    abandonedVAOs.emplace_back(vao);
+    MBGL_CHECK_ERROR(gl::GenVertexArrays(1, &id));
+}
+
+void VAOHolder::reset() {
+    if (!id) return;
+    assert(util::ThreadContext::currentlyOn(util::ThreadType::Map));
+    MBGL_CHECK_ERROR(gl::DeleteVertexArrays(1, &id));
+    id = 0;
 }
 
 void GLObjectStore::abandon(BufferHolder&& buffer) {
@@ -95,18 +99,17 @@ void GLObjectStore::abandon(TexturePoolHolder&& texture) {
     abandonedTexturePools.push_back(std::move(texture));
 }
 
+void GLObjectStore::abandon(VAOHolder&& vao) {
+    assert(util::ThreadContext::currentlyOn(util::ThreadType::Map));
+    abandonedVAOs.push_back(std::move(vao));
+}
+
 void GLObjectStore::performCleanup() {
     assert(util::ThreadContext::currentlyOn(util::ThreadType::Map));
-
-    if (!abandonedVAOs.empty()) {
-        MBGL_CHECK_ERROR(VertexArrayObject::Delete(static_cast<GLsizei>(abandonedVAOs.size()),
-                                                   abandonedVAOs.data()));
-        abandonedVAOs.clear();
-    }
-
     abandonedBuffers.clear();
     abandonedTextures.clear();
     abandonedTexturePools.clear();
+    abandonedVAOs.clear();
 }
 
 } // namespace gl
diff --git a/src/mbgl/gl/gl_object_store.hpp b/src/mbgl/gl/gl_object_store.hpp
index 6a115df0c..684400d44 100644
--- a/src/mbgl/gl/gl_object_store.hpp
+++ b/src/mbgl/gl/gl_object_store.hpp
@@ -98,10 +98,22 @@ private:
     std::array<GLuint, TextureMax> ids;
 };
 
+class VAOHolder : public GLHolder {
+public:
+    VAOHolder() = default;
+    ~VAOHolder() { reset(); }
+
+    VAOHolder(VAOHolder&& o) noexcept : GLHolder(std::move(o)) {}
+    VAOHolder& operator=(VAOHolder&& o) noexcept { GLHolder::operator=(std::move(o)); return *this; }
+
+    void create();
+    void reset();
+};
+
 class GLObjectStore : private util::noncopyable {
 public:
     // Mark OpenGL objects for deletion
-    void abandonVAO(GLuint vao);
+    void abandon(VAOHolder&&);
     void abandon(BufferHolder&&);
     void abandon(TextureHolder&&);
     void abandon(TexturePoolHolder&&);
@@ -113,7 +125,7 @@ public:
 private:
     // We split the holder objects in separate containers because each
     // GLHolder-derived object can vary in size.
-    std::vector<GLuint> abandonedVAOs;
+    std::vector<VAOHolder> abandonedVAOs;
     std::vector<BufferHolder> abandonedBuffers;
     std::vector<TextureHolder> abandonedTextures;
     std::vector<TexturePoolHolder> abandonedTexturePools;