REmove more of the unnecessary GLBacken .h and GPUCOnfig.h include, The gpu::Context is now completely agnostic of the True Backend

interface/src/Application.cpp

@@ -772,8 +772,9 @@ void Application::initializeGL() {
     }
     #endif
 
-    // Where the gpuContext is created and where the TRUE Backend is created and assigned
+    // Where the gpuContext is initialized and where the TRUE Backend is created and assigned
-    _gpuContext = std::make_shared<gpu::Context>(new gpu::GLBackend());
+    gpu::Context::init<gpu::GLBackend>();
+    _gpuContext = std::make_shared<gpu::Context>();
 
     initDisplay();
     qCDebug(interfaceapp, "Initialized Display.");

interface/src/GLCanvas.h

@@ -13,7 +13,6 @@
 #define hifi_GLCanvas_h
 
 #include <QDebug>
-#include <gpu/GPUConfig.h>
 #include <QGLWidget>
 #include <QTimer>
 

libraries/gpu/src/gpu/Context.cpp

@@ -10,13 +10,16 @@
 //
 #include "Context.h"
 
-// this include should disappear! as soon as the gpu::Context is in place
-#include "GLBackend.h"
-
 using namespace gpu;
 
-Context::Context(Backend* backend) :
+Context::CreateBackend Context::_createBackendCallback = nullptr;
-    _backend(backend) {
+Context::MakeProgram Context::_makeProgramCallback = nullptr;
+std::once_flag Context::_initialized;
+
+Context::Context() {
+    if (_createBackendCallback) {
+        _backend.reset(_createBackendCallback());
+    }
 }
 
 Context::Context(const Context& context) {
@@ -26,8 +29,8 @@ Context::~Context() {
 }
 
 bool Context::makeProgram(Shader& shader, const Shader::BindingSet& bindings) {
-    if (shader.isProgram()) {
+    if (shader.isProgram() && _makeProgramCallback) {
-        return GLBackend::makeProgram(shader, bindings);
+        return _makeProgramCallback(shader, bindings);
     }
     return false;
 }

libraries/gpu/src/gpu/Context.h

@@ -12,6 +12,7 @@
 #define hifi_gpu_Context_h
 
 #include <assert.h>
+#include <mutex>
 
 #include "Batch.h"
 
@@ -26,13 +27,12 @@ namespace gpu {
 
 class Backend {
 public:
-
     virtual~ Backend() {};
+
     virtual void render(Batch& batch) = 0;
     virtual void syncCache() = 0;
     virtual void downloadFramebuffer(const FramebufferPointer& srcFramebuffer, const Vec4i& region, QImage& destImage) = 0;
 
-
     class TransformObject {
     public:
         Mat4 _model;
@@ -118,7 +118,21 @@ protected:
 
 class Context {
 public:
-    Context(Backend* backend);
+    typedef Backend* (*CreateBackend)();
+    typedef bool (*MakeProgram)(Shader& shader, const Shader::BindingSet& bindings);
+
+
+    // This one call must happen before any context is created or used (Shader::MakeProgram) in order to setup the Backend and any singleton data needed
+    template <class T>
+    static void init() {
+        std::call_once(_initialized, [] {
+            _createBackendCallback = T::createBackend;
+            _makeProgramCallback = T::makeProgram;
+            T::init();
+        });
+    }
+
+    Context();
     ~Context();
 
     void render(Batch& batch);
@@ -132,13 +146,17 @@ public:
 protected:
     Context(const Context& context);
 
+    std::unique_ptr<Backend> _backend;
+
     // This function can only be called by "static Shader::makeProgram()"
     // makeProgramShader(...) make a program shader ready to be used in a Batch.
     // It compiles the sub shaders, link them and defines the Slots and their bindings.
     // If the shader passed is not a program, nothing happens. 
-    static bool makeProgram(Shader& shader, const Shader::BindingSet& bindings = Shader::BindingSet());
+    static bool makeProgram(Shader& shader, const Shader::BindingSet& bindings);
 
-    std::unique_ptr<Backend> _backend;
+    static CreateBackend _createBackendCallback;
+    static MakeProgram _makeProgramCallback;
+    static std::once_flag _initialized;
 
     friend class Shader;
 };

libraries/gpu/src/gpu/GLBackend.cpp

@@ -63,12 +63,7 @@ GLBackend::CommandCall GLBackend::_commandCalls[Batch::NUM_COMMANDS] =
     (&::gpu::GLBackend::do_glLineWidth),
 };
 
-GLBackend::GLBackend() :
+void GLBackend::init() {
-    _input(),
-    _transform(),
-    _pipeline(),
-    _output()
-{
     static std::once_flag once;
     std::call_once(once, [] {
         qCDebug(gpulogging) << "GL Version: " << QString((const char*) glGetString(GL_VERSION));
@@ -108,7 +103,18 @@ GLBackend::GLBackend() :
         }*/
 #endif
     });
+}
 
+Backend* GLBackend::createBackend() {
+    return new GLBackend();
+}
+
+GLBackend::GLBackend() :
+    _input(),
+    _transform(),
+    _pipeline(),
+    _output()
+{
     initInput();
     initTransform();
 }

libraries/gpu/src/gpu/GLBackend.h

@@ -22,10 +22,17 @@
 namespace gpu {
 
 class GLBackend : public Backend {
-public:
+
+    // Context Backend static interface required
+    friend class Context;
+    static void init();
+    static Backend* createBackend();
+    static bool makeProgram(Shader& shader, const Shader::BindingSet& bindings = Shader::BindingSet());
 
     explicit GLBackend(bool syncCache);
     GLBackend();
+public:
+
     virtual ~GLBackend();
 
     virtual void render(Batch& batch);
@@ -47,7 +54,6 @@ public:
 
     static void checkGLStackStable(std::function<void()> f);
 
-    static bool makeProgram(Shader& shader, const Shader::BindingSet& bindings = Shader::BindingSet());
     
 
     class GLBuffer : public GPUObject {

libraries/render-utils/src/FramebufferCache.cpp

@@ -18,7 +18,6 @@
 #include <QMap>
 #include <QQueue>
 #include <gpu/Batch.h>
-#include <gpu/GPUConfig.h>
 #include "RenderUtilsLogging.h"
 
 static QQueue<gpu::FramebufferPointer> _cachedFramebuffers;

libraries/render/src/render/DrawStatus.cpp

@@ -18,10 +18,7 @@
 #include <ViewFrustum.h>
 #include <RenderArgs.h>
 
-#include <gpu/Batch.h>
 #include <gpu/Context.h>
-#include <gpu/GPUConfig.h>
-#include <gpu/GPULogging.h>
 
 #include "drawItemBounds_vert.h"
 #include "drawItemBounds_frag.h"
@@ -151,17 +148,17 @@ void DrawStatus::run(const SceneContextPointer& sceneContext, const RenderContex
     const unsigned int VEC3_ADRESS_OFFSET = 3;
 
     for (int i = 0; i < nbItems; i++) {
-        batch._glUniform3fv(_drawItemBoundPosLoc, 1, (const GLfloat*) (itemAABox + i));
+        batch._glUniform3fv(_drawItemBoundPosLoc, 1, (const float*) (itemAABox + i));
-        batch._glUniform3fv(_drawItemBoundDimLoc, 1, ((const GLfloat*) (itemAABox + i)) + VEC3_ADRESS_OFFSET);
+        batch._glUniform3fv(_drawItemBoundDimLoc, 1, ((const float*) (itemAABox + i)) + VEC3_ADRESS_OFFSET);
 
         batch.draw(gpu::LINES, 24, 0);
     }
 
     batch.setPipeline(getDrawItemStatusPipeline());
     for (int i = 0; i < nbItems; i++) {
-        batch._glUniform3fv(_drawItemStatusPosLoc, 1, (const GLfloat*) (itemAABox + i));
+        batch._glUniform3fv(_drawItemStatusPosLoc, 1, (const float*) (itemAABox + i));
-        batch._glUniform3fv(_drawItemStatusDimLoc, 1, ((const GLfloat*) (itemAABox + i)) + VEC3_ADRESS_OFFSET);
+        batch._glUniform3fv(_drawItemStatusDimLoc, 1, ((const float*) (itemAABox + i)) + VEC3_ADRESS_OFFSET);
-        batch._glUniform4iv(_drawItemStatusValueLoc, 1, (const GLint*) (itemStatus + i));
+        batch._glUniform4iv(_drawItemStatusValueLoc, 1, (const int*) (itemStatus + i));
 
         batch.draw(gpu::TRIANGLES, 24, 0);
     }

libraries/render/src/render/DrawTask.cpp

@@ -17,9 +17,7 @@
 #include <PerfStat.h>
 #include <RenderArgs.h>
 #include <ViewFrustum.h>
-#include <gpu/Batch.h>
 #include <gpu/Context.h>
-#include <gpu/GPUConfig.h>
 
 using namespace render;
 

tests/render-utils/src/main.cpp

@@ -94,7 +94,6 @@ class QTestWindow : public QWindow {
     QSize _size;
     //TextRenderer* _textRenderer[4];
     RateCounter fps;
-    gpu::ContextPointer _gpuContext;
 
 protected:
     void renderText();
@@ -124,7 +123,8 @@ public:
 
         show();
         makeCurrent();
-        _gpuContext.reset(new gpu::Context(new gpu::GLBackend()));
+
+        gpu::Context::init<gpu::GLBackend>();