Win32: use native OpenGL drivers, if available.

After this commit, if the target system does have modern OpenGL
drivers installed, ANGLE is configured to use them, bypassing most
translation (shaders still have to be translated from ESSL to GLSL).

If there are no OpenGL drivers, such as if the graphics drivers were
installed via Windows Update, DirectX translation is still used. This
results in a very noticeable startup delay and minor performance
degradation.

In addition it is no longer necessary to build with -DOPENGL=1 to be
able to run the binary in wine; everything works out of the box.
Before, wine's incomplete HLSL translator would crash.

This change required renaming the variable `texture` in shaders,
since it shadows the Core GLSL function with the same name, and ANGLE
translates texture2D() calls to texture() calls.

CMakeLists.txt

@@ -187,9 +187,9 @@ if(ENABLE_GUI)
             set(ANGLE_STATIC            ON  CACHE INTERNAL "")
             set(ANGLE_ENABLE_D3D9       ON  CACHE INTERNAL "")
             set(ANGLE_ENABLE_D3D11      ON  CACHE INTERNAL "")
-            set(ANGLE_ENABLE_OPENGL     OFF CACHE INTERNAL "")
+            set(ANGLE_ENABLE_OPENGL     ON  CACHE INTERNAL "")
-            set(ANGLE_ENABLE_ESSL       OFF CACHE INTERNAL "")
+            set(ANGLE_ENABLE_ESSL       ON  CACHE INTERNAL "")
-            set(ANGLE_ENABLE_GLSL       OFF CACHE INTERNAL "")
+            set(ANGLE_ENABLE_GLSL       ON  CACHE INTERNAL "")
             set(ANGLE_ENABLE_HLSL       ON  CACHE INTERNAL "")
             add_vendored_subdirectory(extlib/angle)
             set(OPENGL_LIBRARIES        EGL GLESv2)

res/shaders/imesh.frag

@@ -4,9 +4,9 @@
 // Copyright 2016 Aleksey Egorov
 //-----------------------------------------------------------------------------
 uniform vec4 color;
-uniform sampler2D texture;
+uniform sampler2D texture_;
 
 void main() {
-    if(texture2D(texture, gl_FragCoord.xy / 32.0).a < 0.5) discard;
+    if(texture2D(texture_, gl_FragCoord.xy / 32.0).a < 0.5) discard;
     gl_FragColor = color;
 }

res/shaders/imesh_tex.frag

@@ -4,12 +4,12 @@
 // Copyright 2016 Aleksey Egorov
 //-----------------------------------------------------------------------------
 uniform vec4 color;
-uniform sampler2D texture;
+uniform sampler2D texture_;
 
 varying vec2 fragTex;
 
 void main() {
-    vec4 texColor = texture2D(texture, fragTex);
+    vec4 texColor = texture2D(texture_, fragTex);
     if(texColor.a == 0.0) discard;
     gl_FragColor = texColor * color;
 }

res/shaders/imesh_texa.frag

@@ -4,10 +4,10 @@
 // Copyright 2016 Aleksey Egorov
 //-----------------------------------------------------------------------------
 uniform vec4 color;
-uniform sampler2D texture;
+uniform sampler2D texture_;
 
 varying vec2 fragTex;
 
 void main() {
-    gl_FragColor = vec4(color.rgb, color.a * texture2D(texture, fragTex).TEX_ALPHA);
+    gl_FragColor = vec4(color.rgb, color.a * texture2D(texture_, fragTex).TEX_ALPHA);
 }

res/shaders/mesh_fill.frag

@@ -4,9 +4,9 @@
 // Copyright 2016 Aleksey Egorov
 //-----------------------------------------------------------------------------
 uniform vec4 color;
-uniform sampler2D texture;
+uniform sampler2D texture_;
 
 void main() {
-    if(texture2D(texture, gl_FragCoord.xy / 32.0).TEX_ALPHA < 0.5) discard;
+    if(texture2D(texture_, gl_FragCoord.xy / 32.0).TEX_ALPHA < 0.5) discard;
     gl_FragColor = color;
 }

src/platform/guiwin.cpp

@@ -22,7 +22,9 @@
 
 #if HAVE_OPENGL == 3
 #   define EGLAPI /*static linkage*/
+#   define EGL_EGLEXT_PROTOTYPES
 #   include <EGL/egl.h>
+#   include <EGL/eglext.h>
 #endif
 
 #if defined(HAVE_SPACEWARE)
@@ -498,9 +500,9 @@ public:
 #if HAVE_OPENGL == 1
     HGLRC hGlRc = NULL;
 #elif HAVE_OPENGL == 3
-    EGLDisplay eglDisplay = NULL;
+    static EGLDisplay eglDisplay;
-    EGLSurface eglSurface = NULL;
+    EGLSurface eglSurface = EGL_NO_SURFACE;
-    EGLContext eglContext = NULL;
+    EGLContext eglContext = EGL_NO_CONTEXT;
 #endif
 
     WINDOWPLACEMENT placement = {};
@@ -603,10 +605,32 @@ public:
 
         sscheck(hGlRc = wglCreateContext(hDc));
 #elif HAVE_OPENGL == 3
-        ssassert(eglBindAPI(EGL_OPENGL_ES_API), "Cannot bind EGL API");
+        if(eglDisplay == EGL_NO_DISPLAY) {
+            ssassert(eglBindAPI(EGL_OPENGL_ES_API), "Cannot bind EGL API");
 
-        eglDisplay = eglGetDisplay(hDc);
+            EGLBoolean initialized = EGL_FALSE;
-        ssassert(eglInitialize(eglDisplay, NULL, NULL), "Cannot initialize EGL");
+            for(auto &platformType : {
+                // Try platform types from least to most amount of software translation required.
+                std::make_pair("OpenGL ES",   EGL_PLATFORM_ANGLE_TYPE_OPENGLES_ANGLE),
+                std::make_pair("OpenGL",      EGL_PLATFORM_ANGLE_TYPE_OPENGL_ANGLE),
+                std::make_pair("Direct3D 11", EGL_PLATFORM_ANGLE_TYPE_D3D11_ANGLE),
+                std::make_pair("Direct3D 9",  EGL_PLATFORM_ANGLE_TYPE_D3D9_ANGLE),
+            }) {
+                dbp("Initializing ANGLE with %s backend", platformType.first);
+                EGLint displayAttributes[] = {
+                    EGL_PLATFORM_ANGLE_TYPE_ANGLE, platformType.second,
+                    EGL_NONE
+                };
+                eglDisplay = eglGetPlatformDisplayEXT(EGL_PLATFORM_ANGLE_ANGLE, hDc,
+                                                      displayAttributes);
+                if(eglDisplay != EGL_NO_DISPLAY) {
+                    initialized = eglInitialize(eglDisplay, NULL, NULL);
+                    if(initialized) break;
+                    eglTerminate(eglDisplay);
+                }
+            }
+            ssassert(initialized, "Cannot find a suitable EGL display");
+        }
 
         EGLint configAttributes[] = {
             EGL_COLOR_BUFFER_TYPE,  EGL_RGB_BUFFER,
@@ -1324,6 +1348,8 @@ public:
     }
 };
 
+EGLDisplay WindowImplWin32::eglDisplay = EGL_NO_DISPLAY;
+
 WindowRef CreateWindow(Window::Kind kind, WindowRef parentWindow) {
     return std::make_shared<WindowImplWin32>(kind,
                 std::static_pointer_cast<WindowImplWin32>(parentWindow));

src/render/gl3shader.cpp

@@ -118,6 +118,13 @@ precision highp float;
 
     GLint compiled;
     glGetShaderiv(shader, GL_COMPILE_STATUS, &compiled);
+    if(!compiled) {
+        dbp("Failed to compile shader:\n"
+            "----8<----8<----8<----8<----8<----\n"
+            "%s\n"
+            "----8<----8<----8<----8<----8<----\n",
+            src.c_str());
+    }
     ssassert(compiled, "Cannot compile shader");
 
     return shader;
@@ -220,7 +227,7 @@ void MeshRenderer::Init() {
             { ATTRIB_POS, "pos" },
         }
     );
-    fillShader.SetUniformTextureUnit("texture", 0);
+    fillShader.SetUniformTextureUnit("texture_", 0);
 
     selectedShader = &lightShader;
 }
@@ -957,8 +964,8 @@ void IndexedMeshRenderer::Init() {
         }
     );
 
-    texShader.SetUniformTextureUnit("texture", 0);
+    texShader.SetUniformTextureUnit("texture_", 0);
-    texaShader.SetUniformTextureUnit("texture", 0);
+    texaShader.SetUniformTextureUnit("texture_", 0);
     selectedShader = &colShader;
 }