From 3de9ed645350bd5bc2dc4c9d762021c7980e278f Mon Sep 17 00:00:00 2001
From: Doug Binks <doug@enkisoftware.com>
Date: Wed, 15 Jul 2020 13:21:02 +0100
Subject: [PATCH] Fixed EGL glfwMakeUserContextCurrent - requires different
 surface

---
 src/egl_context.c | 44 +++++++++++++++++++++++++++++++++++++++-----
 src/egl_context.h | 14 ++++++++++++++
 2 files changed, 53 insertions(+), 5 deletions(-)

diff --git a/src/egl_context.c b/src/egl_context.c
index 43615794..7b5bb0f3 100644
--- a/src/egl_context.c
+++ b/src/egl_context.c
@@ -372,6 +372,8 @@ GLFWbool _glfwInitEGL(void)
         _glfw_dlsym(_glfw.egl.handle, "eglQueryString");
     _glfw.egl.GetProcAddress = (PFN_eglGetProcAddress)
         _glfw_dlsym(_glfw.egl.handle, "eglGetProcAddress");
+    _glfw.egl.CreatePbufferSurface = (PFN_eglCreatePbufferSurface)
+        _glfw_dlsym(_glfw.egl.handle, "eglCreatePbufferSurface");
 
     if (!_glfw.egl.GetConfigAttrib ||
         !_glfw.egl.GetConfigs ||
@@ -833,10 +835,10 @@ static void _glfwMakeUserContextCurrentEGL(_GLFWusercontext* context)
 
 static void _glfwDestroyUserContextEGL(_GLFWusercontext* context)
 {
-    if (context->egl.handle)
-    {
-        eglDestroyContext(_glfw.egl.display, context->egl.handle);
-    }
+    if (context->egl.surface!=EGL_NO_SURFACE)
+        eglDestroySurface(_glfw.egl.display,context->egl.surface);
+        
+    eglDestroyContext(_glfw.egl.display, context->egl.handle);
     free(context);
 }
 
@@ -844,6 +846,22 @@ _GLFWusercontext* _glfwCreateUserContextEGL(_GLFWwindow* window)
 {
     _GLFWusercontext* context;
     _GLFWctxconfig ctxconfig;
+    const EGLint auxConfigAttribs[] =
+    {
+        EGL_SURFACE_TYPE, EGL_PBUFFER_BIT,
+        EGL_BLUE_SIZE, 8, EGL_GREEN_SIZE, 8, EGL_RED_SIZE, 8, EGL_ALPHA_SIZE, 8,
+        EGL_DEPTH_SIZE, 0, EGL_STENCIL_SIZE, 0,
+        EGL_NONE
+    };
+    EGLint dummySurfaceAttribs[] =
+    {
+        EGL_WIDTH, 1, EGL_HEIGHT, 1,
+        EGL_TEXTURE_TARGET, EGL_NO_TEXTURE,
+        EGL_TEXTURE_FORMAT, EGL_NO_TEXTURE,
+        EGL_NONE
+    };
+    EGLint dummySurfaceNumConfigs;
+    EGLConfig dummySurfaceConfig;
 
     context = calloc(1, sizeof(_GLFWusercontext));
     context->window = window;
@@ -851,13 +869,29 @@ _GLFWusercontext* _glfwCreateUserContextEGL(_GLFWwindow* window)
     ctxconfig = _glfw.hints.context;
     ctxconfig.share = window;
 
-    if(!_glfwCreateContextForConfigEGL(window,&ctxconfig,&context->egl.handle))
+    if (!_glfwCreateContextForConfigEGL(window,&ctxconfig,&context->egl.handle))
     {
         _glfwInputError(GLFW_PLATFORM_ERROR,
                                 "EGL: Failed to create user OpenGL context");
         free(context);
         return NULL;
     }
+    if (glfwExtensionSupported("EGL_KHR_surfaceless_context"))
+        context->egl.surface = EGL_NO_SURFACE;
+    else
+    {
+        // create dummy surface
+        eglChooseConfig(_glfw.egl.display, auxConfigAttribs, &dummySurfaceConfig, 1, &dummySurfaceNumConfigs);
+        context->egl.surface = eglCreatePbufferSurface(_glfw.egl.display, dummySurfaceConfig, dummySurfaceAttribs);
+        if (!context->egl.surface)
+        {
+            eglDestroyContext(_glfw.egl.display, context->egl.handle);
+            _glfwInputError(GLFW_PLATFORM_ERROR,
+                                    "EGL: Failed to create surface for user context and EGL_KHR_surfaceless_context not supported");
+            free(context);
+            return NULL;
+        }
+    }
 
     context->makeCurrent = _glfwMakeUserContextCurrentEGL;
     context->destroy = _glfwDestroyUserContextEGL;
diff --git a/src/egl_context.h b/src/egl_context.h
index 1dcab099..62801740 100644
--- a/src/egl_context.h
+++ b/src/egl_context.h
@@ -71,6 +71,12 @@
 #define EGL_NO_DISPLAY ((EGLDisplay) 0)
 #define EGL_NO_CONTEXT ((EGLContext) 0)
 #define EGL_DEFAULT_DISPLAY ((EGLNativeDisplayType) 0)
+#define EGL_PBUFFER_BIT 0x0001
+#define EGL_HEIGHT 0x3056
+#define EGL_WIDTH 0x3057
+#define EGL_NO_TEXTURE 0x305C
+#define EGL_TEXTURE_FORMAT 0x3080
+#define EGL_TEXTURE_TARGET 0x3081
 
 #define EGL_CONTEXT_OPENGL_FORWARD_COMPATIBLE_BIT_KHR 0x00000002
 #define EGL_CONTEXT_OPENGL_CORE_PROFILE_BIT_KHR 0x00000001
@@ -130,6 +136,8 @@ typedef EGLBoolean (EGLAPIENTRY * PFN_eglSwapBuffers)(EGLDisplay,EGLSurface);
 typedef EGLBoolean (EGLAPIENTRY * PFN_eglSwapInterval)(EGLDisplay,EGLint);
 typedef const char* (EGLAPIENTRY * PFN_eglQueryString)(EGLDisplay,EGLint);
 typedef GLFWglproc (EGLAPIENTRY * PFN_eglGetProcAddress)(const char*);
+typedef EGLSurface (EGLAPIENTRY * PFN_eglCreatePbufferSurface)(EGLDisplay,EGLConfig,const EGLint*);
+typedef EGLBoolean (EGLAPIENTRY * PFN_eglChooseConfig)(EGLDisplay,EGLint const*,EGLConfig*,EGLint,EGLint*);
 #define eglGetConfigAttrib _glfw.egl.GetConfigAttrib
 #define eglGetConfigs _glfw.egl.GetConfigs
 #define eglGetDisplay _glfw.egl.GetDisplay
@@ -146,6 +154,8 @@ typedef GLFWglproc (EGLAPIENTRY * PFN_eglGetProcAddress)(const char*);
 #define eglSwapInterval _glfw.egl.SwapInterval
 #define eglQueryString _glfw.egl.QueryString
 #define eglGetProcAddress _glfw.egl.GetProcAddress
+#define eglCreatePbufferSurface _glfw.egl.CreatePbufferSurface
+#define eglChooseConfig  _glfw.egl.ChooseConfig
 
 typedef EGLDisplay (EGLAPIENTRY * PFNEGLGETPLATFORMDISPLAYEXTPROC)(EGLenum,void*,const EGLint*);
 typedef EGLSurface (EGLAPIENTRY * PFNEGLCREATEPLATFORMWINDOWSURFACEEXTPROC)(EGLDisplay,EGLConfig,void*,const EGLint*);
@@ -169,6 +179,8 @@ typedef struct _GLFWcontextEGL
 typedef struct _GLFWusercontextEGL
 {
    EGLContext       handle;
+   EGLSurface       surface;
+
 } _GLFWusercontextEGL;
 
 
@@ -214,6 +226,8 @@ typedef struct _GLFWlibraryEGL
     PFN_eglSwapInterval         SwapInterval;
     PFN_eglQueryString          QueryString;
     PFN_eglGetProcAddress       GetProcAddress;
+    PFN_eglCreatePbufferSurface CreatePbufferSurface;
+    PFN_eglChooseConfig         ChooseConfig;
 
     PFNEGLGETPLATFORMDISPLAYEXTPROC GetPlatformDisplayEXT;
     PFNEGLCREATEPLATFORMWINDOWSURFACEEXTPROC CreatePlatformWindowSurfaceEXT;