Force OpenGL Core Profile context on macOS

By default, SDL creates an OpenGL 2.1 context on macOS for an OpenGL
renderer. As a consequence, mipmapping is not supported.

Force to use a core profile context, to get a higher version.

Before:

    INFO: Renderer: opengl
    INFO: OpenGL version: 2.1 NVIDIA-14.0.32 355.11.11.10.10.143
    WARN: Trilinear filtering disabled (OpenGL 3.0+ or ES 2.0+ required)

After:

    INFO: Renderer: opengl
    DEBUG: Creating OpenGL Core Profile context
    INFO: OpenGL version: 4.1 NVIDIA-14.0.32 355.11.11.10.10.143
    INFO: Trilinear filtering enabled

when running with:

    scrcpy --verbosity=debug --render-driver=opengl

Note:
Since SDL_CreateRenderer causes a fallback to OpenGL 2.1, the profile
and version attributes have to be set and the context created _after_.

app/src/display.c

@@ -23,6 +23,22 @@ sc_display_init(struct sc_display *display, SDL_Window *window, bool mipmaps) {
     // starts with "opengl"
     bool use_opengl = renderer_name && !strncmp(renderer_name, "opengl", 6);
     if (use_opengl) {
+
+#ifdef SC_DISPLAY_FORCE_OPENGL_CORE_PROFILE
+        // Persuade macOS to give us something better than OpenGL 2.1.
+        // If we create a Core Profile context, we get the best OpenGL version.
+        SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK,
+                            SDL_GL_CONTEXT_PROFILE_CORE);
+
+        LOGD("Creating OpenGL Core Profile Context");
+        display->gl_context = SDL_GL_CreateContext(window);
+        if (!display->gl_context) {
+            LOGE("Could not create OpenGL context: %s", SDL_GetError());
+            SDL_DestroyRenderer(display->renderer);
+            return false;
+        }
+#endif
+
         struct sc_opengl *gl = &display->gl;
         sc_opengl_init(gl);
 
@@ -51,6 +67,9 @@ sc_display_init(struct sc_display *display, SDL_Window *window, bool mipmaps) {
 
 void
 sc_display_destroy(struct sc_display *display) {
+#ifdef SC_DISPLAY_FORCE_OPENGL_CORE_PROFILE
+    SDL_GL_DeleteContext(display->gl_context);
+#endif
     if (display->texture) {
         SDL_DestroyTexture(display->texture);
     }

app/src/display.h

@@ -10,11 +10,19 @@
 #include "coords.h"
 #include "opengl.h"
 
+#ifdef __APPLE__
+# define SC_DISPLAY_FORCE_OPENGL_CORE_PROFILE
+#endif
+
 struct sc_display {
     SDL_Renderer *renderer;
     SDL_Texture *texture;
 
     struct sc_opengl gl;
+#ifdef SC_DISPLAY_FORCE_OPENGL_CORE_PROFILE
+    SDL_GLContext *gl_context;
+#endif
+
     bool mipmaps;
 };