first draft at glx headless rendering

[skip ci]

common/headless_view.cpp

@@ -13,6 +13,7 @@ void notify_map_change(MapChange change) {
 }
 
 HeadlessView::HeadlessView() {
+#if LLMR_USE_CGL
     // TODO: test if OpenGL 4.1 with GL_ARB_ES2_compatibility is supported
     // If it is, use kCGLOGLPVersion_3_2_Core and enable that extension.
     CGLPixelFormatAttribute attributes[] = {
@@ -36,6 +37,26 @@ HeadlessView::HeadlessView() {
         fprintf(stderr, "Error creating GL context object\n");
         return;
     }
+#endif
+
+ #ifdef USE_GLX
+    x_display = XOpenDisplay(0);
+
+    static int pixelFormat[] = {
+        GLX_RGBA,
+        GLX_DOUBLEBUFFER,
+        GLX_RED_SIZE, 8,
+        GLX_GREEN_SIZE, 8,
+        GLX_BLUE_SIZE, 8,
+        GLX_ALPHA_SIZE, 8,
+        GLX_DEPTH_SIZE, 24,
+        GLX_STENCIL_SIZE, 8,
+        None
+    };
+
+    x_info = glXChooseVisual(x_display, DefaultScreen(x_display), pixelFormat);
+    gl_context = glXCreateContext(display, x_info, 0, GL_TRUE);
+  #endif
 
     make_active();
 }
@@ -44,6 +65,7 @@ HeadlessView::HeadlessView() {
 void HeadlessView::resize(int width, int height) {
     clear_buffers();
 
+#if LLMR_USE_CGL
     // Create depth/stencil buffer
     glGenRenderbuffersEXT(1, &fbo_depth_stencil);
     glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, fbo_depth_stencil);
@@ -74,9 +96,17 @@ void HeadlessView::resize(int width, int height) {
         }
         return;
     }
+#endif
+
+#if LLMR_USE_GLX
+    x_pixmap = XCreatePixmap(display, DefaultRootWindow(display), width, height, 32);
+    glx_pixmap = glXCreateGLXPixmap(display, x_info, x_pixmap);
+#endif
+
 }
 
 void HeadlessView::clear_buffers() {
+#if LLMR_USE_CGL
     glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
 
     if (fbo) {
@@ -93,24 +123,52 @@ void HeadlessView::clear_buffers() {
         glDeleteRenderbuffersEXT(1, &fbo_depth_stencil);
         fbo_depth_stencil = 0;
     }
+#endif
+
+#if LLMR_USE_GLX
+    if (glx_pixmap) {
+        glXDestroyGLXPixmap(x_display, glx_pixmap);
+        glx_pixmap = nullptr;
+    }
+
+    if (x_pixmap) {
+        XFreePixmap(x_display, x_pixmap);
+        x_pixmap = nullptr;
+    }
+#endif
 }
 
 HeadlessView::~HeadlessView() {
     clear_buffers();
+
+#if LLMR_USE_CGL
     CGLDestroyContext(gl_context);
+#endif
 }
 
 void HeadlessView::make_active() {
+#if LLMR_USE_CGL
     CGLError error = CGLSetCurrentContext(gl_context);
     if (error) {
         fprintf(stderr, "Switching OpenGL context failed\n");
     }
+#endif
+
+#if LLMR_USE_GLX
+    if (!glXMakeCurrent(display, glx_pixmap, gl_context)) {
+        fprintf(stderr, "Switching OpenGL context failed\n");
+    }
+#endif
 }
 
 void HeadlessView::swap() {}
 
 unsigned int HeadlessView::root_fbo() {
+#if LLMR_USE_CGL
     return fbo;
+#endif
+
+    return 0;
 }
 
 }

common/headless_view.hpp

@@ -1,6 +1,15 @@
 #ifndef LLMR_COMMON_HEADLESS_CGL
 #define LLMR_COMMON_HEADLESS_CGL
 
+#ifdef __APPLE__
+#define LLMR_USE_CGL 1
+#define LLMR_CONTEXT_OBJ CGLContextObj
+#else
+#include <GL/glx.h>
+#define LLMR_USE_GLX 1
+#define LLMR_CONTEXT_OBJ GLXContext
+#endif
+
 #include <llmr/map/view.hpp>
 #include <llmr/platform/gl.hpp>
 
@@ -22,10 +31,20 @@ private:
 
 
 private:
-    CGLContextObj gl_context;
+    LLMR_CONTEXT_OBJ gl_context;
+
+#ifdef LLMR_USE_CGL
     GLuint fbo = 0;
     GLuint fbo_depth_stencil = 0;
     GLuint fbo_color = 0;
+#endif
+
+#ifdef LLMR_USE_GLX
+    XVisualInfo *x_info = nullptr;
+    Display *x_display = nullptr;
+    Pixmap x_pixmap;
+    GLXPixmap glx_pixmap;
+#endif
 };
 
 }