pxscene · ashwinikalokhe · Apr 1, 2020 · Apr 1, 2020
diff --git a/examples/pxScene2d/src/glut/pxContextUtils.cpp b/examples/pxScene2d/src/glut/pxContextUtils.cpp
@@ -18,23 +18,369 @@ limitations under the License.
 
 #include "pxContextUtils.h"
 
+#include <GL/gl.h>
+#include <GL/glu.h>
+
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <GL/glx.h>
+#include <X11/Xlib.h>
+
+
+#include <map>
+#include "rtLog.h"
+#include "rtMutex.h"
+
+bool glContextIsCurrent = false;
+rtMutex eglContextMutex;
 int nextInternalContextId = 1;
+#define GL_MAJOR_VERSION                  0x821B
+#define GL_MINOR_VERSION                  0x821C
+typedef GLXContext (*glXCreateContextAttribsARBProc)(Display*, GLXFBConfig, GLXContext, Bool, const int*);
+
+extern GLXContext *openGLContext;
+#define GLX_CONTEXT_MAJOR_VERSION_ARB       0x2091
+#define GLX_CONTEXT_MINOR_VERSION_ARB       0x2092
+typedef GLXContext (*glXCreateContextAttribsARBProc)(Display*, GLXFBConfig, GLXContext, Bool, const int*);
+
+// Helper to check for extension string presence.  Adapted from:
+//   http://www.opengl.org/resources/features/OGLextensions/
+static bool isExtensionSupported(const char *extList, const char *extension)
+{
+  const char *start;
+  const char *where, *terminator;
+
+  /* Extension names should not have spaces. */
+  where = strchr(extension, ' ');
+  if (where || *extension == '\0')
+    return false;
+
+  /* It takes a bit of care to be fool-proof about parsing the
+     OpenGL extensions string. Don't be fooled by sub-strings,
+     etc. */
+  for (start=extList;;) {
+    where = strstr(start, extension);
+
+    if (!where)
+      break;
+
+    terminator = where + strlen(extension);
+
+    if ( where == start || *(where - 1) == ' ' )
+      if ( *terminator == ' ' || *terminator == '\0' )
+        return true;
+
+    start = terminator;
+  }
+
+  return false;
+}
+std::map<int, GLXContext *> internalContexts;
+static bool ctxErrorOccurred = false;
+static int ctxErrorHandler( Display *dpy, XErrorEvent *ev )
+{
+    ctxErrorOccurred = true;
+    return 0;
+}
+
+GLXContext* getContext()
+{
+  Display *display = XOpenDisplay(NULL);
+
+  if (!display)
+  {
+    printf("Failed to open X display\n");
+    return NULL;
+  }
+
+  // Get a matching FB config
+  static int visual_attribs[] =
+    {
+      GLX_X_RENDERABLE    , True,
+      GLX_DRAWABLE_TYPE   , GLX_WINDOW_BIT,
+      GLX_RENDER_TYPE     , GLX_RGBA_BIT,
+      GLX_X_VISUAL_TYPE   , GLX_TRUE_COLOR,
+      GLX_RED_SIZE        , 8,
+      GLX_GREEN_SIZE      , 8,
+      GLX_BLUE_SIZE       , 8,
+      GLX_ALPHA_SIZE      , 8,
+      GLX_DEPTH_SIZE      , 24,
+      GLX_STENCIL_SIZE    , 8,
+      GLX_DOUBLEBUFFER    , True,
+      //GLX_SAMPLE_BUFFERS  , 1,
+      //GLX_SAMPLES         , 4,
+      None
+    };
+
+  int glx_major, glx_minor;
+
+  // FBConfigs were added in GLX version 1.3.
+  if ( !glXQueryVersion( display, &glx_major, &glx_minor ) || 
+       ( ( glx_major == 1 ) && ( glx_minor < 3 ) ) || ( glx_major < 1 ) )
+  {
+    printf("Invalid GLX version");
+    return NULL;
+  }
+
+  printf( "Getting matching framebuffer configs\n" );
+  int fbcount;
+  GLXFBConfig* fbc = glXChooseFBConfig(display, DefaultScreen(display), visual_attribs, &fbcount);
+  if (!fbc)
+  {
+    printf( "Failed to retrieve a framebuffer config\n" );
+    return NULL;
+  }
+  printf( "Found %d matching FB configs.\n", fbcount );
+
+  // Pick the FB config/visual with the most samples per pixel
+  printf( "Getting XVisualInfos\n" );
+  int best_fbc = -1, worst_fbc = -1, best_num_samp = -1, worst_num_samp = 999;
+
+  int i;
+  for (i=0; i<fbcount; ++i)
+  {
+    XVisualInfo *vi = glXGetVisualFromFBConfig( display, fbc[i] );
+    if ( vi )
+    {
+      int samp_buf, samples;
+      glXGetFBConfigAttrib( display, fbc[i], GLX_SAMPLE_BUFFERS, &samp_buf );
+      glXGetFBConfigAttrib( display, fbc[i], GLX_SAMPLES       , &samples  );
+
+      printf( "  Matching fbconfig %d, visual ID 0x%2x: SAMPLE_BUFFERS = %d,"
+              " SAMPLES = %d\n", 
+              i, vi -> visualid, samp_buf, samples );
+
+      if ( best_fbc < 0 || samp_buf && samples > best_num_samp )
+        best_fbc = i, best_num_samp = samples;
+      if ( worst_fbc < 0 || !samp_buf || samples < worst_num_samp )
+        worst_fbc = i, worst_num_samp = samples;
+    }
+    XFree( vi );
+  }
+
+  GLXFBConfig bestFbc = fbc[ best_fbc ];
+
+  // Be sure to free the FBConfig list allocated by glXChooseFBConfig()
+  XFree( fbc );
+
+  // Get a visual
+  XVisualInfo *vi = glXGetVisualFromFBConfig( display, bestFbc );
+  printf( "Chosen visual ID = 0x%x\n", vi->visualid );
+
+  printf( "Creating colormap\n" );
+  XSetWindowAttributes swa;
+  Colormap cmap;
+  swa.colormap = cmap = XCreateColormap( display,
+                                         RootWindow( display, vi->screen ), 
+                                         vi->visual, AllocNone );
+  swa.background_pixmap = None ;
+  swa.border_pixel      = 0;
+  swa.event_mask        = StructureNotifyMask;
 
-pxError createInternalContext(int &id, bool /*depthBuffer*/)
+  printf( "Creating window\n" );
+  Window win = XCreateWindow( display, RootWindow( display, vi->screen ), 
+                              0, 0, 100, 100, 0, vi->depth, InputOutput, 
+                              vi->visual, 
+                              CWBorderPixel|CWColormap|CWEventMask, &swa );
+  if ( !win )
+  {
+    printf( "Failed to create window.\n" );
+    return NULL;
+  }
+
+  // Done with the visual info data
+  XFree( vi );
+
+  XStoreName( display, win, "GL 3.0 Window" );
+
+  printf( "Mapping window\n" );
+  XMapWindow( display, win );
+
+  // Get the default screen's GLX extension list
+  const char *glxExts = glXQueryExtensionsString( display,
+                                                  DefaultScreen( display ) );
+
+  // NOTE: It is not necessary to create or make current to a context before
+  // calling glXGetProcAddressARB
+  glXCreateContextAttribsARBProc glXCreateContextAttribsARB = 0;
+  glXCreateContextAttribsARB = (glXCreateContextAttribsARBProc)
+           glXGetProcAddressARB( (const GLubyte *) "glXCreateContextAttribsARB" );
+
+  GLXContext ctx = 0;
+
+  // Install an X error handler so the application won't exit if GL 3.0
+  // context allocation fails.
+  //
+  // Note this error handler is global.  All display connections in all threads
+  // of a process use the same error handler, so be sure to guard against other
+  // threads issuing X commands while this code is running.
+  bool ctxErrorOccurred = false;
+  int (*oldHandler)(Display*, XErrorEvent*) =
+      XSetErrorHandler(&ctxErrorHandler);
+
+  // Check for the GLX_ARB_create_context extension string and the function.
+  // If either is not present, use GLX 1.3 context creation method.
+  if ( !isExtensionSupported( glxExts, "GLX_ARB_create_context" ) ||
+       !glXCreateContextAttribsARB )
+  {
+    printf( "glXCreateContextAttribsARB() not found"
+            " ... using old-style GLX context\n" );
+    ctx = glXCreateNewContext( display, bestFbc, GLX_RGBA_TYPE, 0, True );
+  }
+
+  // If it does, try to get a GL 2.1 context!
+  else
+  {
+    int context_attribs[] =
+      {
+        GLX_CONTEXT_MAJOR_VERSION_ARB, 2,
+        GLX_CONTEXT_MINOR_VERSION_ARB, 1,
+        //GLX_CONTEXT_FLAGS_ARB        , GLX_CONTEXT_FORWARD_COMPATIBLE_BIT_ARB,
+        None
+      };
+
+    printf( "Creating context\n" );
+    ctx = glXCreateContextAttribsARB( display, bestFbc, 0,
+                                      True, context_attribs );
+
+    // Sync to ensure any errors generated are processed.
+    XSync( display, False );
+    if ( !ctxErrorOccurred && ctx )
+      printf( "Created GL 2.1 context\n" );
+    else
+    {
+      // Couldn't create GL 3.0 context.  Fall back to old-style 2.x context.
+      // When a context version below 3.0 is requested, implementations will
+      // return the newest context version compatible with OpenGL versions less
+      // than version 3.0.
+      // GLX_CONTEXT_MAJOR_VERSION_ARB = 1
+      context_attribs[1] = 1;
+      // GLX_CONTEXT_MINOR_VERSION_ARB = 0
+      context_attribs[3] = 0;
+
+      ctxErrorOccurred = false;
+
+      printf( "Failed to create GL 2.1 context"
+              " ... using old-style GLX context\n" );
+      ctx = glXCreateContextAttribsARB( display, bestFbc, 0, 
+                                        True, context_attribs );
+    }
+  }
+
+  // Sync to ensure any errors generated are processed.
+  XSync( display, False );
+
+  // Restore the original error handler
+  XSetErrorHandler( oldHandler );
+
+  if ( ctxErrorOccurred || !ctx )
+  {
+    printf( "Failed to create an OpenGL context\n" );
+    return NULL;
+  }
+
+  // Verifying that context is a direct context
+  if ( ! glXIsDirect ( display, ctx ) )
+  {
+    printf( "Indirect GLX rendering context obtained\n" );
+  }
+  else
+  {
+    printf( "Direct GLX rendering context obtained\n" );
+  }
+
+  printf( "Making context current\n" );
+  glXMakeCurrent( display, win, ctx );
+
+  glClearColor( 0, 0.5, 1, 1 );
+  glClear( GL_COLOR_BUFFER_BIT );
+  glXSwapBuffers ( display, win );
+
+  glClearColor ( 1, 0.5, 0, 1 );
+  glClear ( GL_COLOR_BUFFER_BIT );
+  glXSwapBuffers ( display, win );
+
+  glXMakeCurrent( display, 0, 0 );
+  glXDestroyContext( display, ctx );
+
+  XDestroyWindow( display, win );
+  XFreeColormap( display, cmap );
+  XCloseDisplay( display );
+
+  return &ctx;
+}
+
+pxError createGLContext(int id, bool depthBuffer)
 {
-  id = nextInternalContextId++;
-  //TODO
+    GLXContext *context = NULL;
+    rtMutexLockGuard eglContextMutexGuard(eglContextMutex);
+    if ( internalContexts.find(id) != internalContexts.end() )
+    {
+        context = internalContexts.at(id);
+    }
+    if (context == NULL)
+    {  
+    internalContexts[id] = getContext();
+    }
+    return PX_OK;
+}
+
+pxError createInternalContext(int &id, bool depthBuffer)
+{
+  {
+    rtMutexLockGuard eglContextMutexGuard(eglContextMutex);
+    id = nextInternalContextId++;
+  }
+  createGLContext(id, depthBuffer);
   return PX_OK;
 }
 
-pxError deleteInternalGLContext(int)
+pxError deleteInternalGLContext(int id)
 {
-  //TODO
+  rtMutexLockGuard eglContextMutexGuard(eglContextMutex);
+  if ( internalContexts.find(id) != internalContexts.end() )
+  {
+    internalContexts.erase(id);
+  }
   return PX_OK;
 }
 
-pxError makeInternalGLContextCurrent(bool, int)
+pxError makeInternalGLContextCurrent(bool current, int id)
 {
-  //TODO
+  if (current)
+    {
+        GLXContext *context = NULL;
+        {
+          rtMutexLockGuard eglContextMutexGuard(eglContextMutex);
+          if (internalContexts.find(id) != internalContexts.end())
+          {
+            context = internalContexts.at(id);
+          }
+        }
+        if (context != NULL)
+        {
+            createGLContext(id, false);
+            {
+              rtMutexLockGuard eglContextMutexGuard(eglContextMutex);
+              context = internalContexts[id];
+            }
+           // [context makeCurrentContext];
+
+            #if 0
+            glEnable(GL_BLEND);
+            glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
+            #endif
+            glClearColor(0, 0, 0, 0);
+            glClear(GL_COLOR_BUFFER_BIT);
+        }
+        glContextIsCurrent = true;
+    }
+    else
+    {
+        glFlush();
+       // [openGLContext makeCurrentContext];
+        glContextIsCurrent = false;
+    }
   return PX_OK;
 }