Linux offscreen OpenGL using glxpixmaps. also fix FBO ARB/EXT issues

1 files changed, 132 insertions, 12 deletions

diff --git a/tests/fbo.cc b/tests/fbo.cc
index 403a32e..b7bf1c0 100644
--- a/tests/fbo.cc
+++ b/tests/fbo.cc
@@ -15,13 +15,94 @@ fbo_t *fbo_new()
 
 #define REPORTGLERROR(task) { GLenum tGLErr = glGetError(); if (tGLErr != GL_NO_ERROR) { std::cout << "OpenGL error " << tGLErr << " while " << task << "\n"; } }
 
-bool fbo_init(fbo_t *fbo, size_t width, size_t height)
+bool use_ext()
+{
+  // do we need to use the EXT or ARB version?
+  if (!glewIsSupported("GL_ARB_framebuffer_object") &&
+        glewIsSupported("GL_EXT_framebuffer_object")) {
+    return true;
+  } else {
+    return false;
+  }
+}
+
+bool check_fbo_status()
 {
-  if (!glewIsSupported("GL_ARB_framebuffer_object")) {
-    fprintf(stderr, "Framebuffer extension not found\n");
+	/* This code is based on user V-man code from
+	http://www.opengl.org/wiki/GL_EXT_framebuffer_multisample
+	See also: http://www.songho.ca/opengl/gl_fbo.html */
+	GLenum status;
+	bool result = false;
+	if (use_ext())
+		status = glCheckFramebufferStatusEXT(GL_FRAMEBUFFER_EXT);
+	else
+		status = glCheckFramebufferStatus(GL_FRAMEBUFFER);
+
+	if (glGetError() != GL_NO_ERROR)
+		fprintf(stderr, "OpenGL Error %i\n",glGetError());
+
+	if (status == GL_FRAMEBUFFER_COMPLETE)
+		result = true;
+	else if (status == GL_FRAMEBUFFER_UNSUPPORTED)
+		fprintf(stderr, "GL_FRAMEBUFFER_UNSUPPORTED\n");
+	else if (status == GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT)
+		fprintf(stderr, "GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT\n");
+	else if (status == GL_FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT)
+		fprintf(stderr, "GL_FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT\n");
+	else if (status == GL_FRAMEBUFFER_INCOMPLETE_DIMENSIONS_EXT)
+		fprintf(stderr, "GL_FRAMEBUFFER_INCOMPLETE_DIMENSIONS_EXT\n");
+	else if (status == GL_FRAMEBUFFER_INCOMPLETE_FORMATS_EXT)
+		fprintf(stderr, "GL_FRAMEBUFFER_INCOMPLETE_FORMATS_EXT\n");
+	else if (status == GL_FRAMEBUFFER_INCOMPLETE_DRAW_BUFFER_EXT)
+		fprintf(stderr, "GL_FRAMEBUFFER_INCOMPLETE_DRAW_BUFFER_EXT\n");
+	else if (status == GL_FRAMEBUFFER_INCOMPLETE_READ_BUFFER_EXT)
+		fprintf(stderr, "GL_FRAMEBUFFER_INCOMPLETE_READ_BUFFER_EXT\n");
+	else if (status == GL_FRAMEBUFFER_INCOMPLETE_MULTISAMPLE_EXT)
+		fprintf(stderr, "GL_FRAMEBUFFER_INCOMPLETE_MULTISAMPLE_EXT\n");
+	else
+		fprintf(stderr, "Unknown Code: glCheckFramebufferStatusEXT returned %i\n",status);
+	return result;
+}
+
+bool fbo_ext_init(fbo_t *fbo, size_t width, size_t height)
+{
+  // Generate and bind FBO
+  glGenFramebuffersEXT(1, &fbo->fbo_id);
+  glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, fbo->fbo_id);
+  REPORTGLERROR("binding framebuffer");
+
+  // Generate depth and render buffers
+  glGenRenderbuffersEXT(1, &fbo->depthbuf_id);
+  glGenRenderbuffersEXT(1, &fbo->renderbuf_id);
+
+  // Create buffers with correct size
+  if (!fbo_resize(fbo, width, height)) return false;
+
+  // Attach render and depth buffers
+  glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT, 
+                               GL_RENDERBUFFER_EXT, fbo->renderbuf_id);
+  REPORTGLERROR("specifying color render buffer");
+
+
+  if (!check_fbo_status()) {
+    fprintf(stderr, "Problem with OpenGL framebuffer after specifying color render buffer.\n");
+    return false;
+  }
+
+  glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_DEPTH_ATTACHMENT_EXT, 
+                               GL_RENDERBUFFER_EXT, fbo->depthbuf_id);
+  REPORTGLERROR("specifying depth render buffer");
+
+  if (!check_fbo_status()) {
+    fprintf(stderr, "Problem with OpenGL framebuffer after specifying depth render buffer.\n");
     return false;
   }
 
+  return true;
+}
+
+bool fbo_arb_init(fbo_t *fbo, size_t width, size_t height)
+{
   // Generate and bind FBO
   glGenFramebuffers(1, &fbo->fbo_id);
   glBindFramebuffer(GL_FRAMEBUFFER, fbo->fbo_id);
@@ -56,15 +137,48 @@ bool fbo_init(fbo_t *fbo, size_t width, size_t height)
   return true;
 }
 
-bool fbo_resize(fbo_t *fbo, size_t width, size_t height)
+
+bool fbo_init(fbo_t *fbo, size_t width, size_t height)
 {
-  glBindRenderbuffer(GL_RENDERBUFFER, fbo->depthbuf_id);
-  glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT24, width, height);
-  REPORTGLERROR("creating depth render buffer");
+  /*
+  Some OpenGL drivers include the framebuffer functions but not with
+  core or ARB names, only with the EXT name. This has been worked-around
+  by deciding at runtime, using GLEW, which version needs to be used. See also:
+  
+  http://www.opengl.org/wiki/Framebuffer_Object
+  http://stackoverflow.com/questions/6912988/glgenframebuffers-or-glgenframebuffersex
+  http://www.devmaster.net/forums/showthread.php?t=10967
+  */
+
+  bool result = false;
+  if (glewIsSupported("GL_ARB_framebuffer_object"))
+    result = fbo_arb_init(fbo, width, height);
+  else if (use_ext())
+    result = fbo_ext_init(fbo, width, height);
+  else
+    fprintf(stderr, "Framebuffer Object extension not found by GLEW\n");
+  return result;
+}
 
-  glBindRenderbuffer(GL_RENDERBUFFER, fbo->renderbuf_id);
-  glRenderbufferStorage(GL_RENDERBUFFER, GL_RGBA8, width, height);
-  REPORTGLERROR("creating color render buffer");
+bool fbo_resize(fbo_t *fbo, size_t width, size_t height)
+{
+  if (use_ext()) {
+    glBindRenderbufferEXT(GL_RENDERBUFFER, fbo->depthbuf_id);
+    glRenderbufferStorageEXT(GL_RENDERBUFFER, GL_DEPTH_COMPONENT24, width, height);
+    REPORTGLERROR("creating depth render buffer");
+
+    glBindRenderbufferEXT(GL_RENDERBUFFER, fbo->renderbuf_id);
+    glRenderbufferStorageEXT(GL_RENDERBUFFER, GL_RGBA8, width, height);
+    REPORTGLERROR("creating color render buffer");
+  } else {
+    glBindRenderbuffer(GL_RENDERBUFFER, fbo->depthbuf_id);
+    glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT24, width, height);
+    REPORTGLERROR("creating depth render buffer");
+
+    glBindRenderbuffer(GL_RENDERBUFFER, fbo->renderbuf_id);
+    glRenderbufferStorage(GL_RENDERBUFFER, GL_RGBA8, width, height);
+    REPORTGLERROR("creating color render buffer");
+  }
 
   return true;
 }
@@ -77,11 +191,17 @@ void fbo_delete(fbo_t *fbo)
 GLuint fbo_bind(fbo_t *fbo)
 {
   glGetIntegerv(GL_FRAMEBUFFER_BINDING, (GLint *)&fbo->old_fbo_id);
-  glBindFramebuffer(GL_FRAMEBUFFER, fbo->fbo_id);
+  if (use_ext())
+    glBindFramebufferEXT(GL_FRAMEBUFFER, fbo->fbo_id);
+  else
+    glBindFramebuffer(GL_FRAMEBUFFER, fbo->fbo_id);
   return fbo->old_fbo_id;
 }
 
 void fbo_unbind(fbo_t *fbo)
 {
-  glBindFramebuffer(GL_FRAMEBUFFER, fbo->old_fbo_id);
+  if (use_ext())
+    glBindFramebufferEXT(GL_FRAMEBUFFER, fbo->old_fbo_id);
+  else
+    glBindFramebuffer(GL_FRAMEBUFFER, fbo->old_fbo_id);
 }