[cogl/wip/rib/master-next: 3/10] onscreen: Support point sample based onscreen rendering

[Robert Bragg <rbragg src gnome org>]

commit 3f9081deb0497e84207420da24fb6152d7d05f38
Author: Robert Bragg <robert linux intel com>
Date:   Sun Aug 21 21:27:13 2011 +0100

    onscreen: Support point sample based onscreen rendering
    
    This adds support for point sample based rendering of onscreen windows
    whereby multiple point samples per pixel can be requested and if the
    hardware supports that it typically results in reduced aliasing
    (especially considering the jagged edges of polygons)

 cogl/cogl-framebuffer-private.h |    1 +
 cogl/cogl-onscreen-template.c   |   18 ++++++++++++++++++
 cogl/cogl-onscreen-template.h   |   19 +++++++++++++++++++
 cogl/winsys/cogl-winsys-egl.c   |    8 ++++++++
 cogl/winsys/cogl-winsys-glx.c   |    9 +++++++++
 5 files changed, 55 insertions(+), 0 deletions(-)
---
diff --git a/cogl/cogl-framebuffer-private.h b/cogl/cogl-framebuffer-private.h
index fd17b55..b827217 100644
--- a/cogl/cogl-framebuffer-private.h
+++ b/cogl/cogl-framebuffer-private.h
@@ -51,6 +51,7 @@ typedef struct
 {
   CoglSwapChain *swap_chain;
   gboolean need_stencil;
+  int point_samples_per_pixel;
 } CoglFramebufferConfig;
 
 struct _CoglFramebuffer
diff --git a/cogl/cogl-onscreen-template.c b/cogl/cogl-onscreen-template.c
index b9fbd23..5cad939 100644
--- a/cogl/cogl-onscreen-template.c
+++ b/cogl/cogl-onscreen-template.c
@@ -65,6 +65,24 @@ cogl_onscreen_template_new (CoglSwapChain *swap_chain)
     onscreen_template->config.swap_chain = cogl_swap_chain_new ();
 
   onscreen_template->config.need_stencil = TRUE;
+  onscreen_template->config.point_samples_per_pixel = 0;
+
+  user_config = getenv ("COGL_POINT_SAMPLES_PER_PIXEL");
+  if (user_config)
+    {
+      unsigned long point_samples_per_pixel = strtoul (user_config, NULL, 10);
+      if (point_samples_per_pixel != ULONG_MAX)
+        onscreen_template->config.point_samples_per_pixel =
+          point_samples_per_pixel;
+    }
 
   return _cogl_onscreen_template_object_new (onscreen_template);
 }
+
+void
+cogl_onscreen_template_set_point_samples_per_pixel (
+                                        CoglOnscreenTemplate *onscreen_template,
+                                        int samples_per_pixel)
+{
+  onscreen_template->config.point_samples_per_pixel = samples_per_pixel;
+}
diff --git a/cogl/cogl-onscreen-template.h b/cogl/cogl-onscreen-template.h
index 4769f9f..d4a0ea5 100644
--- a/cogl/cogl-onscreen-template.h
+++ b/cogl/cogl-onscreen-template.h
@@ -43,6 +43,25 @@ typedef struct _CoglOnscreenTemplate	      CoglOnscreenTemplate;
 CoglOnscreenTemplate *
 cogl_onscreen_template_new (CoglSwapChain *swap_chain);
 
+/**
+ * cogl_onscreen_template_set_point_samples_per_pixel:
+ * @onscreen: A #CoglOnscreenTemplate template framebuffer
+ * @n: The minimum number of samples per pixel
+ *
+ * Requires that any future CoglOnscreen framebuffers derived from
+ * this template must support making @n point samples per pixel which
+ * will all contribute to the final resolved color for that pixel.
+ *
+ * By default sampling is not based on point samples but rather by
+ * considering the whole rectangular area of the current pixel, so an
+ * @n value of %1 is not equivalent to the default behaviour. A value
+ * of %0 can be used to explicitly request non point based sampling.
+ */
+void
+cogl_onscreen_template_set_point_samples_per_pixel (
+                                          CoglOnscreenTemplate *onscreen_template,
+                                          int n);
+
 G_END_DECLS
 
 #endif /* __COGL_ONSCREEN_TEMPLATE_H__ */
diff --git a/cogl/winsys/cogl-winsys-egl.c b/cogl/winsys/cogl-winsys-egl.c
index 9a40a60..72b678e 100644
--- a/cogl/winsys/cogl-winsys-egl.c
+++ b/cogl/winsys/cogl-winsys-egl.c
@@ -644,6 +644,14 @@ egl_attributes_from_framebuffer_config (CoglDisplay *display,
   attributes[i++] = EGL_SURFACE_TYPE;
   attributes[i++] = EGL_WINDOW_BIT;
 
+  if (config->point_samples_per_pixel)
+    {
+       attributes[i++] = EGL_SAMPLE_BUFFERS;
+       attributes[i++] = 1;
+       attributes[i++] = EGL_SAMPLES;
+       attributes[i++] = config->point_samples_per_pixel;
+    }
+
   attributes[i++] = EGL_NONE;
 
   g_assert (i < MAX_EGL_CONFIG_ATTRIBS);
diff --git a/cogl/winsys/cogl-winsys-glx.c b/cogl/winsys/cogl-winsys-glx.c
index 860c6e5..b3a7caf 100644
--- a/cogl/winsys/cogl-winsys-glx.c
+++ b/cogl/winsys/cogl-winsys-glx.c
@@ -485,6 +485,15 @@ glx_attributes_from_framebuffer_config (CoglDisplay *display,
   attributes[i++] = GLX_STENCIL_SIZE;
   attributes[i++] = config->need_stencil ? 1: GLX_DONT_CARE;
 
+  if (glx_renderer->glx_major == 1 && glx_renderer->glx_minor >= 4 &&
+      config->point_samples_per_pixel)
+    {
+       attributes[i++] = GLX_SAMPLE_BUFFERS;
+       attributes[i++] = 1;
+       attributes[i++] = GLX_SAMPLES;
+       attributes[i++] = config->point_samples_per_pixel;
+    }
+
   attributes[i++] = None;
 
   g_assert (i < MAX_GLX_CONFIG_ATTRIBS);