experimental pbuffer support

[skip ci]

common/headless_display.cpp

@@ -27,30 +27,42 @@ HeadlessDisplay::HeadlessDisplay() {
     if (!XInitThreads()) {
         throw std::runtime_error("Failed to XInitThreads");
     }
-    
-    x_display = XOpenDisplay(0);
 
+    x_display = XOpenDisplay(nullptr);
     if (x_display == nullptr) {
         throw std::runtime_error("Failed to open X display");
     }
 
+    const char *extensions = (char *)glXQueryServerString(x_display, DefaultScreen(x_display), GLX_EXTENSIONS);
+    if (!extensions) {
+        throw std::runtime_error("Cannot read GLX extensions");
+    }
+    if (!strstr(extensions,"GLX_SGIX_fbconfig")) {
+        throw std::runtime_error("Extension GLX_SGIX_fbconfig was not found");
+    }
+    if (!strstr(extensions, "GLX_SGIX_pbuffer")) {
+        throw std::runtime_error("Cannot find glXCreateContextAttribsARB");
+    }
+
+
     static int pixelFormat[] = {
-        GLX_RGBA,
-        GLX_DOUBLEBUFFER,
+        GLX_DOUBLEBUFFER, False,
         GLX_RED_SIZE, 8,
         GLX_GREEN_SIZE, 8,
         GLX_BLUE_SIZE, 8,
         GLX_ALPHA_SIZE, 8,
         GLX_DEPTH_SIZE, 24,
         GLX_STENCIL_SIZE, 8,
-        0
+        None
     };
 
-    x_info = glXChooseVisual(x_display, DefaultScreen(x_display), pixelFormat);
-
-    if (x_info == nullptr) {
-        throw std::runtime_error("Error pixel format");
+    int configs = 0;
+    fb_configs = glXChooseFBConfig(x_display, DefaultScreen(x_display), pixelFormat, &configs);
+    if (configs <= 0) {
+        throw std::runtime_error("No Framebuffer configurations");
     }
+
+    XSync(x_display, False);
 #endif
 }
 
@@ -60,7 +72,7 @@ HeadlessDisplay::~HeadlessDisplay() {
 #endif
 
 #if MBGL_USE_GLX
-    XFree(x_info);
+    XFree(fb_configs);
     XCloseDisplay(x_display);
 #endif
 }

common/headless_display.hpp

@@ -16,7 +16,7 @@ public:
 
 #if MBGL_USE_GLX
     Display *x_display = nullptr;
-    XVisualInfo *x_info = nullptr;
+    GLXFBConfig *fb_configs = nullptr;
 #endif
 };
 

common/headless_view.cpp

@@ -5,6 +5,11 @@
 #include <sstream>
 #include <string>
 
+#if MBGL_USE_GLX
+typedef GLXContext (*glXCreateContextAttribsARBProc)(Display *, GLXFBConfig, GLXContext, Bool, const int *);
+static glXCreateContextAttribsARBProc glXCreateContextAttribsARB = nullptr;
+#endif
+
 namespace mbgl {
 
 HeadlessView::HeadlessView()
@@ -31,13 +36,29 @@ void HeadlessView::createContext() {
 #endif
 
 #if MBGL_USE_GLX
-    x_display = display_->x_display;
-    x_info = display_->x_info;
+    if (glXCreateContextAttribsARB == nullptr) {
+        glXCreateContextAttribsARB = (glXCreateContextAttribsARBProc)glXGetProcAddressARB((const GLubyte *)"glXCreateContextAttribsARB");
+    }
+    if (glXCreateContextAttribsARB == nullptr) {
+        throw std::runtime_error("Cannot find glXCreateContextAttribsARB");
+    }
 
-    gl_context = glXCreateContext(x_display, x_info, 0, GL_TRUE);
+    x_display = display_->x_display;
+    fb_configs = display_->fb_configs;
+
+
+    int attributes[] = {
+        GLX_CONTEXT_MAJOR_VERSION_ARB, 2,
+        GLX_CONTEXT_MINOR_VERSION_ARB, 1,
+        GLX_CONTEXT_FLAGS_ARB, GLX_CONTEXT_DEBUG_BIT_ARB,
+        GLX_CONTEXT_PROFILE_MASK_ARB, GLX_CONTEXT_COMPATIBILITY_PROFILE_BIT_ARB,
+        None
+    };
+    gl_context = glXCreateContextAttribsARB(x_display, fb_configs[0], 0, True, attributes);
     if (gl_context == nullptr) {
         throw std::runtime_error("Error creating GL context object");
     }
+
 #endif
 }
 
@@ -92,8 +113,12 @@ void HeadlessView::resize(uint16_t width, uint16_t height, float pixelRatio) {
 #endif
 
 #if MBGL_USE_GLX
-    x_pixmap = XCreatePixmap(x_display, DefaultRootWindow(x_display), w, h, 32);
-    glx_pixmap = glXCreateGLXPixmap(x_display, x_info, x_pixmap);
+    int attributes[] = {
+        GLX_PBUFFER_WIDTH, w,
+        GLX_PBUFFER_HEIGHT, h,
+        None
+    };
+    GLXPbuffer pbuffer = glXCreatePbuffer(x_display, fg_configs[0], attributes);
 #endif
 }
 
@@ -135,17 +160,12 @@ void HeadlessView::clear_buffers() {
 #endif
 
 #if MBGL_USE_GLX
-    if (glx_pixmap) {
-        glXDestroyGLXPixmap(x_display, glx_pixmap);
-        glx_pixmap = 0;
-    }
-
-    if (x_pixmap) {
-        XFreePixmap(x_display, x_pixmap);
-        x_pixmap = 0;
-    }
-
     make_inactive();
+
+    if (glx_pbuffer) {
+        glXDestroyPbuffer(x_display, glx_pbuffer);
+        glx_pbuffer = 0;
+    }
 #endif
 }
 
@@ -178,7 +198,7 @@ void HeadlessView::make_active() {
 #endif
 
 #if MBGL_USE_GLX
-    if (!glXMakeCurrent(x_display, glx_pixmap, gl_context)) {
+    if (!glXMakeContextCurrent(x_display, glx_pbuffer, glx_pbuffer, gl_context)) {
         throw std::runtime_error("Switching OpenGL context failed\n");
     }
 #endif
@@ -193,7 +213,7 @@ void HeadlessView::make_inactive() {
 #endif
 
 #if MBGL_USE_GLX
-    if (!glXMakeCurrent(x_display, 0, NULL)) {
+    if (!glXMakeContextCurrent(x_display, 0, 0, nullptr)) {
         throw std::runtime_error("Removing OpenGL context failed\n");
     }
 #endif

common/headless_view.hpp

@@ -53,10 +53,9 @@ private:
 
 #if MBGL_USE_GLX
     Display *x_display = nullptr;
-    XVisualInfo *x_info = nullptr;
+    GLXFBConfig *fb_configs = nullptr;
     GLXContext gl_context = nullptr;
-    Pixmap x_pixmap = 0;
-    GLXPixmap glx_pixmap = 0;
+    GLXPBuffer glx_pbuffer = 0;
 #endif
 };