[Xcb] [PATCH] Improve opengl tutorial

[Thomas Fischer]

---
diff --git a/opengl.mdwn b/opengl.mdwn
index 4573512..8b9ec9e 100644
--- a/opengl.mdwn
+++ b/opengl.mdwn
@@ -51,6 +51,28 @@ To maintain backward compatibility and providing an
incremental porting path, th
#include <GL/glx.h>
#include <GL/gl.h>

+ /*
+ Attribs filter the list of FBConfigs returned by
glXChooseFBConfig().
+ Visual attribs further described in
glXGetFBConfigAttrib(3)
+ */
+ 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
+ };
+
void draw()
{
glClearColor(0.2, 0.4, 0.9, 1.0);
@@ -95,16 +117,17 @@ To maintain backward compatibility and providing an
incremental porting path, th
{
int visualID = 0;

- /* Query framebuffer configurations */
+ /* Query framebuffer configurations that match
visual_attribs */
GLXFBConfig *fb_configs = 0;
int num_fb_configs = 0;
- fb_configs = glXGetFBConfigs(display,
default_screen, &num_fb_configs);
+ fb_configs = glXChooseFBConfig(display,
default_screen, visual_attribs, &num_fb_configs);
if(!fb_configs || num_fb_configs == 0)
{
fprintf(stderr, "glXGetFBConfigs failed\n");
return -1;
}
-
+ printf("Found %d matching FB configs",
num_fb_configs);
+
/* Select first framebuffer config and query
visualID */
GLXFBConfig fb_config = fb_configs[0];
glXGetFBConfigAttrib(display, fb_config,
GLX_VISUAL_ID , &visualID);
---