From c9cb20d8496dab334f3e9339012d32d56853a9fb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Vladim=C3=ADr=20Vondru=C5=A1?= <mosra@centrum.cz>
Date: Sat, 18 May 2013 11:17:51 +0200
Subject: [PATCH] Call glClearDepth() if glClearDepthf() is not available.

---
 src/Context.cpp  |  2 ++
 src/Renderer.cpp | 34 ++++++++++++++++++++++++++++++----
 src/Renderer.h   | 20 +++++++++++++++++---
 3 files changed, 49 insertions(+), 7 deletions(-)

diff --git a/src/Context.cpp b/src/Context.cpp
index 4d0ed0e7c..67818d458 100644
--- a/src/Context.cpp
+++ b/src/Context.cpp
@@ -40,6 +40,7 @@
 #include "Framebuffer.h"
 #include "Mesh.h"
 #include "Renderbuffer.h"
+#include "Renderer.h"
 
 #include "Implementation/State.h"
 
@@ -368,6 +369,7 @@ Context::Context() {
     Framebuffer::initializeContextBasedFunctionality(this);
     Mesh::initializeContextBasedFunctionality(this);
     Renderbuffer::initializeContextBasedFunctionality(this);
+    Renderer::initializeContextBasedFunctionality(this);
 }
 
 Context::~Context() {
diff --git a/src/Renderer.cpp b/src/Renderer.cpp
index 9284c3896..b74e66e60 100644
--- a/src/Renderer.cpp
+++ b/src/Renderer.cpp
@@ -26,9 +26,17 @@
 
 #include "Color.h"
 #include "Math/Geometry/Rectangle.h"
+#include "Context.h"
+#include "Extensions.h"
 
 namespace Magnum {
 
+#ifndef MAGNUM_TARGET_GLES
+Renderer::ClearDepthfImplementation Renderer::clearDepthfImplementation = &Renderer::clearDepthfImplementationDefault;
+#else
+Renderer::ClearDepthfImplementation Renderer::clearDepthfImplementation = &Renderer::clearDepthfImplementationES;
+#endif
+
 void Renderer::setFeature(const Feature feature, const bool enabled) {
     enabled ? glEnable(GLenum(feature)) : glDisable(GLenum(feature));
 }
@@ -47,10 +55,6 @@ void Renderer::setClearDepth(const Double depth) {
 }
 #endif
 
-void Renderer::setClearDepth(const Float depth) {
-    glClearDepthf(depth);
-}
-
 void Renderer::setClearStencil(const Int stencil) {
     glClearStencil(stencil);
 }
@@ -149,4 +153,26 @@ void Renderer::setLogicOperation(const LogicOperation operation) {
 }
 #endif
 
+void Renderer::initializeContextBasedFunctionality(Context* context) {
+    #ifndef MAGNUM_TARGET_GLES
+    if(context->isExtensionSupported<Extensions::GL::ARB::ES2_compatibility>()) {
+        Debug() << "Renderer: using" << Extensions::GL::ARB::ES2_compatibility::string() << "features";
+
+        clearDepthfImplementation = &Renderer::clearDepthfImplementationES;
+    }
+    #else
+    static_cast<void>(context);
+    #endif
+}
+
+#ifndef MAGNUM_TARGET_GLES
+void Renderer::clearDepthfImplementationDefault(const GLfloat depth) {
+    glClearDepth(depth);
+}
+#endif
+
+void Renderer::clearDepthfImplementationES(const GLfloat depth) {
+    glClearDepthf(depth);
+}
+
 }
diff --git a/src/Renderer.h b/src/Renderer.h
index aba39ab23..7798d6ede 100644
--- a/src/Renderer.h
+++ b/src/Renderer.h
@@ -43,6 +43,8 @@ Access to global renderer configuration.
 @todo @extension{ARB,viewport_array}
 */
 class MAGNUM_EXPORT Renderer {
+    friend class Context;
+
     public:
         Renderer() = delete;
 
@@ -226,10 +228,12 @@ class MAGNUM_EXPORT Renderer {
          * @overload
          *
          * @see @ref Feature "Feature::DepthTest", @fn_gl{ClearDepth}
-         * @requires_gl41 %Extension @extension{ARB,ES2_compatibility}
-         * @todo Call double version if the extension is not available
+         * If OpenGL ES, OpenGL 4.1 or extension @extension{ARB,ES2_compatibility}
+         * is not available, this function behaves exactly as setClearDepth(Double).
          */
-        static void setClearDepth(Float depth);
+        inline static void setClearDepth(Float depth) {
+            clearDepthfImplementation(depth);
+        }
 
         /**
          * @brief Set clear stencil
@@ -835,6 +839,16 @@ class MAGNUM_EXPORT Renderer {
         }
 
         /*@}*/
+
+    private:
+        static void MAGNUM_LOCAL initializeContextBasedFunctionality(Context* context);
+
+        typedef void(*ClearDepthfImplementation)(GLfloat);
+        #ifndef MAGNUM_TARGET_GLES
+        static void MAGNUM_LOCAL clearDepthfImplementationDefault(GLfloat depth);
+        #endif
+        static void MAGNUM_LOCAL clearDepthfImplementationES(GLfloat depth);
+        static ClearDepthfImplementation clearDepthfImplementation;
 };
 
 }