Mesh rework, part 5: tracking currently bound VAO.

If the VAO is already bound, not calling glBindVertexArray() again.

src/Implementation/MeshState.h

@@ -0,0 +1,30 @@
+#ifndef Magnum_Implementation_MeshState_h
+#define Magnum_Implementation_MeshState_h
+/*
+    Copyright © 2010, 2011, 2012 Vladimír Vondruš <mosra@centrum.cz>
+
+    This file is part of Magnum.
+
+    Magnum is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Lesser General Public License version 3
+    only, as published by the Free Software Foundation.
+
+    Magnum is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+    GNU Lesser General Public License version 3 for more details.
+*/
+
+#include "Magnum.h"
+
+namespace Magnum { namespace Implementation {
+
+struct MeshState {
+    inline MeshState(): currentVAO(0) {}
+
+    GLuint currentVAO;
+};
+
+}}
+
+#endif

src/Implementation/State.cpp

@@ -16,16 +16,18 @@
 #include "State.h"
 
 #include "BufferState.h"
+#include "MeshState.h"
 #include "ShaderProgramState.h"
 #include "TextureState.h"
 
 namespace Magnum { namespace Implementation {
 
-State::State(): buffer(new BufferState), shaderProgram(new ShaderProgramState), texture(new TextureState) {}
+State::State(): buffer(new BufferState), mesh(new MeshState), shaderProgram(new ShaderProgramState), texture(new TextureState) {}
 
 State::~State() {
     delete texture;
     delete shaderProgram;
+    delete mesh;
     delete buffer;
 }
 

src/Implementation/State.h

@@ -20,6 +20,7 @@
 namespace Magnum { namespace Implementation {
 
 struct BufferState;
+struct MeshState;
 struct ShaderProgramState;
 struct TextureState;
 
@@ -28,6 +29,7 @@ struct State {
     ~State();
 
     BufferState* const buffer;
+    MeshState* const mesh;
     ShaderProgramState* const shaderProgram;
     TextureState* const texture;
 };

src/IndexedMesh.cpp

@@ -63,8 +63,7 @@ void IndexedMesh::bindIndexBufferImplementationDefault() {}
 
 #ifndef MAGNUM_TARGET_GLES
 void IndexedMesh::bindIndexBufferImplementationVAO() {
-    glBindVertexArray(vao);
+    bindVAO(vao);
-
     _indexBuffer->bind(Buffer::Target::ElementArray);
 }
 #endif

src/Mesh.cpp

@@ -20,6 +20,8 @@
 #include "Buffer.h"
 #include "Context.h"
 #include "Extensions.h"
+#include "Implementation/MeshState.h"
+#include "Implementation/State.h"
 
 using namespace std;
 
@@ -31,6 +33,14 @@ Mesh::BindAttributeImplementation Mesh::bindAttributeImplementation = &Mesh::bin
 Mesh::BindImplementation Mesh::bindImplementation = &Mesh::bindImplementationDefault;
 Mesh::UnbindImplementation Mesh::unbindImplementation = &Mesh::unbindImplementationDefault;
 
+Mesh::~Mesh() {
+    /* Remove current vao from the state */
+    GLuint& current = Context::current()->state()->mesh->currentVAO;
+    if(current == vao) current = 0;
+
+    (this->*destroyImplementation)();
+}
+
 Mesh::Mesh(Mesh&& other): vao(other.vao), _primitive(other._primitive), _vertexCount(other._vertexCount), attributes(other.attributes) {
     other.vao = 0;
 }
@@ -57,6 +67,11 @@ void Mesh::draw() {
     unbind();
 }
 
+void Mesh::bindVAO(GLuint vao) {
+    GLuint& current = Context::current()->state()->mesh->currentVAO;
+    if(current != vao) glBindVertexArray(current = vao);
+}
+
 void Mesh::bind() {
     CORRADE_ASSERT((_vertexCount == 0) == attributes.empty(), "Mesh: vertex count is non-zero, but no attributes are bound", );
 
@@ -125,7 +140,7 @@ void Mesh::bindAttributeImplementationDefault(const Attribute&) {}
 
 #ifndef MAGNUM_TARGET_GLES
 void Mesh::bindAttributeImplementationVAO(const Attribute& attribute) {
-    glBindVertexArray(vao);
+    bindVAO(vao);
     vertexAttribPointer(attribute);
 }
 #endif
@@ -137,7 +152,7 @@ void Mesh::bindImplementationDefault() {
 
 #ifndef MAGNUM_TARGET_GLES
 void Mesh::bindImplementationVAO() {
-    glBindVertexArray(vao);
+    bindVAO(vao);
 }
 #endif
 
@@ -148,7 +163,7 @@ void Mesh::unbindImplementationDefault() {
 
 #ifndef MAGNUM_TARGET_GLES
 void Mesh::unbindImplementationVAO() {
-    glBindVertexArray(0);
+    bindVAO(0);
 }
 #endif
 

src/Mesh.h

@@ -81,7 +81,8 @@ Basic workflow is to set up respective shader (see @ref AbstractShaderProgram-re
 
 If @extension{APPLE,vertex_array_object} is supported, VAOs are used instead
 of binding the buffers and specifying vertex attribute pointers in each
-draw() call.
+draw() call. The engine tracks currently bound VAO to avoid unnecessary calls
+to @fn_gl{BindVertexArray}.
 
 @requires_gl30 Extension @extension{EXT,gpu_shader4} (for unsigned integer attributes)
 
@@ -354,9 +355,7 @@ class MAGNUM_EXPORT Mesh {
          * @see @fn_gl{DeleteVertexArrays} (if
          *      @extension{APPLE,vertex_array_object} is available)
          */
-        inline virtual ~Mesh() {
+        virtual ~Mesh();
-            (this->*destroyImplementation)();
-        }
 
         /** @brief Move assignment */
         Mesh& operator=(Mesh&& other);
@@ -571,6 +570,8 @@ class MAGNUM_EXPORT Mesh {
 
         void MAGNUM_EXPORT addVertexAttribute(Buffer* buffer, GLuint location, GLint count, Type type, GLintptr offset, GLsizei stride);
 
+        static void MAGNUM_LOCAL bindVAO(GLuint vao);
+
         void MAGNUM_LOCAL bind();
 
         inline void unbind() {
@@ -591,7 +592,7 @@ class MAGNUM_EXPORT Mesh {
         #ifndef MAGNUM_TARGET_GLES
         void MAGNUM_LOCAL destroyImplementationVAO();
         #endif
-        static DestroyImplementation destroyImplementation;
+        static MAGNUM_LOCAL DestroyImplementation destroyImplementation;
 
         typedef void(Mesh::*BindAttributeImplementation)(const Attribute&);
         void MAGNUM_LOCAL bindAttributeImplementationDefault(const Attribute& attribute);