[cogl/wip/quadbuffer-stereo: 2/7] Add a simple example of stereo drawing

[Owen Taylor <otaylor src gnome org>]

commit 18a51c6616cb1974638f3d2096c41485b25e5156
Author: Owen W. Taylor <otaylor fishsoup net>
Date:   Thu May 1 20:35:10 2014 -0400

    Add a simple example of stereo drawing
    
    Add a new example that draws a triangle floating in the air in
    front of the screen.

 examples/cogl-stereo.c |  155 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 155 insertions(+), 0 deletions(-)
---
diff --git a/examples/cogl-stereo.c b/examples/cogl-stereo.c
new file mode 100644
index 0000000..8e7666b
--- /dev/null
+++ b/examples/cogl-stereo.c
@@ -0,0 +1,155 @@
+#include <cogl/cogl.h>
+#include <glib.h>
+#include <stdio.h>
+
+typedef struct _Data
+{
+    CoglContext *ctx;
+    CoglFramebuffer *fb;
+    CoglPrimitive *left_triangle;
+    CoglPrimitive *right_triangle;
+    CoglPipeline *pipeline;
+
+    unsigned int redraw_idle;
+    CoglBool is_dirty;
+    CoglBool draw_ready;
+} Data;
+
+static gboolean
+paint_cb (void *user_data)
+{
+    Data *data = user_data;
+
+    data->redraw_idle = 0;
+    data->is_dirty = FALSE;
+    data->draw_ready = FALSE;
+
+    cogl_framebuffer_set_stereo_mode (data->fb, COGL_STEREO_BOTH);
+    cogl_framebuffer_clear4f (data->fb, COGL_BUFFER_BIT_COLOR, 0, 0, 0, 1);
+
+    cogl_framebuffer_set_stereo_mode (data->fb, COGL_STEREO_LEFT);
+    cogl_primitive_draw (data->left_triangle,
+                         data->fb,
+                         data->pipeline);
+
+    if (cogl_framebuffer_get_is_stereo (data->fb))
+      {
+       cogl_framebuffer_set_stereo_mode (data->fb, COGL_STEREO_RIGHT);
+       cogl_primitive_draw (data->right_triangle,
+                            data->fb,
+                            data->pipeline);
+      }
+
+    cogl_onscreen_swap_buffers (data->fb);
+
+    return G_SOURCE_REMOVE;
+}
+
+static void
+maybe_redraw (Data *data)
+{
+    if (data->is_dirty && data->draw_ready && data->redraw_idle == 0) {
+        /* We'll draw on idle instead of drawing immediately so that
+         * if Cogl reports multiple dirty rectangles we won't
+         * redundantly draw multiple frames */
+        data->redraw_idle = g_idle_add (paint_cb, data);
+    }
+}
+
+static void
+frame_event_cb (CoglOnscreen *onscreen,
+                CoglFrameEvent event,
+                CoglFrameInfo *info,
+                void *user_data)
+{
+    Data *data = user_data;
+
+    if (event == COGL_FRAME_EVENT_SYNC) {
+        data->draw_ready = TRUE;
+        maybe_redraw (data);
+    }
+}
+
+static void
+dirty_cb (CoglOnscreen *onscreen,
+          const CoglOnscreenDirtyInfo *info,
+          void *user_data)
+{
+    Data *data = user_data;
+
+    data->is_dirty = TRUE;
+    maybe_redraw (data);
+}
+
+int
+main (int argc, char **argv)
+{
+    Data data;
+    CoglRenderer *renderer;
+    CoglOnscreenTemplate *onscreen_template;
+    CoglDisplay *display;
+    CoglOnscreen *onscreen;
+    CoglError *error = NULL;
+    CoglVertexP2C4 left_triangle_vertices[] = {
+        {0.05, 0.7, 0xff, 0x00, 0x00, 0xff},
+        {-0.65, -0.7, 0x00, 0xff, 0x00, 0xff},
+        {0.75, -0.7, 0x00, 0x00, 0xff, 0xff}
+    };
+    CoglVertexP2C4 right_triangle_vertices[] = {
+        {-0.05, 0.7, 0xff, 0x00, 0x00, 0xff},
+        {-0.75, -0.7, 0x00, 0xff, 0x00, 0xff},
+        {0.65, -0.7, 0x00, 0x00, 0xff, 0xff}
+    };
+    GSource *cogl_source;
+    GMainLoop *loop;
+
+    data.redraw_idle = 0;
+    data.is_dirty = FALSE;
+    data.draw_ready = TRUE;
+
+    renderer = cogl_renderer_new ();
+    onscreen_template = cogl_onscreen_template_new (NULL);
+    cogl_onscreen_template_set_stereo_enabled (onscreen_template, TRUE);
+    display = cogl_display_new (renderer, onscreen_template);
+
+    data.ctx = cogl_context_new (display, &error);
+    if (!data.ctx) {
+        fprintf (stderr, "Failed to create context: %s\n", error->message);
+        return 1;
+    }
+
+    onscreen = cogl_onscreen_new (data.ctx, 640, 480);
+    cogl_onscreen_show (onscreen);
+    data.fb = onscreen;
+
+    if (!cogl_framebuffer_get_is_stereo (data.fb))
+       fprintf (stderr, "Could not create stereo framebuffer\n");
+
+    cogl_onscreen_set_resizable (onscreen, TRUE);
+
+    data.left_triangle = cogl_primitive_new_p2c4 (data.ctx,
+                                                 COGL_VERTICES_MODE_TRIANGLES,
+                                                 3, left_triangle_vertices);
+    data.right_triangle = cogl_primitive_new_p2c4 (data.ctx,
+                                                  COGL_VERTICES_MODE_TRIANGLES,
+                                                  3, right_triangle_vertices);
+    data.pipeline = cogl_pipeline_new (data.ctx);
+
+    cogl_source = cogl_glib_source_new (data.ctx, G_PRIORITY_DEFAULT);
+
+    g_source_attach (cogl_source, NULL);
+
+    cogl_onscreen_add_frame_callback (data.fb,
+                                      frame_event_cb,
+                                      &data,
+                                      NULL); /* destroy notify */
+    cogl_onscreen_add_dirty_callback (data.fb,
+                                      dirty_cb,
+                                      &data,
+                                      NULL); /* destroy notify */
+
+    loop = g_main_loop_new (NULL, TRUE);
+    g_main_loop_run (loop);
+
+    return 0;
+}