Rewrite expose to preserve the depth buffer

Sorted objects are now drawn with depth testing enabled. Unsorted
objects are drawn without depth testing. This mostly affects
GRITS_LEVEL_WORD+n objects.

Objects at other levels such as BACKGROUND, OVERLAY, and HUD should
generally disable sorting so that they are always drawn to the screen.
For those levels, the depth-buffer is set to read-only. This preserves
the depth buffer so  that it can be used later on to get the world-level
depth at a given screen location.

diff --git a/src/grits-opengl.c b/src/grits-opengl.c
index 323e7f34b67e2d03dfc57aab84fe2a05d84309dc..961a875207c57b1109503d64877a38399c31c4d5 100644 (file)
--- a/src/grits-opengl.c
+++ b/src/grits-opengl.c
@@ -188,22 +188,39 @@ static gboolean on_configure(GritsOpenGL *opengl, GdkEventConfigure *event, gpoi
 
 static gboolean _draw_level(gpointer key, gpointer value, gpointer user_data)
 {
-       g_debug("GritsOpenGL: _draw_level - level=%-4ld", (glong)key);
        GritsOpenGL *opengl = user_data;
+       glong lnum = (glong)key;
        struct RenderLevel *level = value;
+
+       g_debug("GritsOpenGL: _draw_level - level=%-4ld", lnum);
        int nsorted = 0, nunsorted = 0;
        GList *cur = NULL;
 
-       /* Draw opaque objects without sorting */
-       glDepthMask(TRUE);
-       glClear(GL_DEPTH_BUFFER_BIT);
+       /* Configure individual levels */
+       if (lnum < GRITS_LEVEL_WORLD) {
+               /* Disable depth for background levels */
+               glDepthMask(FALSE);
+               glDisable(GL_ALPHA_TEST);
+       } else if (lnum < GRITS_LEVEL_OVERLAY) {
+               /* Enable depth and alpha for world levels */
+               glEnable(GL_ALPHA_TEST);
+               glAlphaFunc(GL_GREATER, 0.1);
+               glDepthMask(TRUE);
+       } else {
+               /* Disable depth for Overlay/HUD levels */
+               // This causes rendering glitches not sure why..
+               //glDepthMask(FALSE);
+       }
+
+       /* Draw unsorted objects without depth testing,
+        * these are polygons, etc, rather than physical objects */
+       glDisable(GL_DEPTH_TEST);
        for (cur = level->unsorted.next; cur; cur = cur->next, nunsorted++)
                grits_object_draw(GRITS_OBJECT(cur->data), opengl);
 
-       /* Freeze depth buffer and draw transparent objects sorted */
-       /* TODO: sorting */
-       //glDepthMask(FALSE);
-       glAlphaFunc(GL_GREATER, 0.1);
+       /* Draw sorted objects using depth testing
+        * These are things that are actually part of the world */
+       glEnable(GL_DEPTH_TEST);
        for (cur = level->sorted.next; cur; cur = cur->next, nsorted++)
                grits_object_draw(GRITS_OBJECT(cur->data), opengl);
 
@@ -220,7 +237,7 @@ static gboolean on_expose(GritsOpenGL *opengl, GdkEventExpose *event, gpointer _
 
        gtk_gl_begin(GTK_WIDGET(opengl));
 
-       glClear(GL_COLOR_BUFFER_BIT);
+       glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 
        _set_visuals(opengl);
 #ifdef ROAM_DEBUG
@@ -233,13 +250,9 @@ static gboolean on_expose(GritsOpenGL *opengl, GdkEventExpose *event, gpointer _
        //roam_sphere_draw_normals(opengl->sphere);
 #else
        g_mutex_lock(opengl->objects_lock);
-       g_tree_foreach(opengl->objects, _draw_level, opengl);
-       if (opengl->wireframe) {
-               glClear(GL_DEPTH_BUFFER_BIT);
+       if (opengl->wireframe)
                glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
-               roam_sphere_draw(opengl->sphere);
-               g_tree_foreach(opengl->objects, _draw_level, opengl);
-       }
+       g_tree_foreach(opengl->objects, _draw_level, opengl);
        g_mutex_unlock(opengl->objects_lock);
 #endif
 

diff --git a/src/plugins/elev.c b/src/plugins/elev.c
index d8c645610a1ce6c0418a4b2c14a7140ab0177766..342bc4bde0067eaaadce959df5ad39915024c98c 100644 (file)
--- a/src/plugins/elev.c
+++ b/src/plugins/elev.c
@@ -300,7 +300,7 @@ GritsPluginElev *grits_plugin_elev_new(GritsViewer *viewer)
 
        /* Add renderers */
        if (LOAD_OPENGL)
-               grits_viewer_add(viewer, GRITS_OBJECT(elev->tiles), GRITS_LEVEL_WORLD, 0);
+               grits_viewer_add(viewer, GRITS_OBJECT(elev->tiles), GRITS_LEVEL_WORLD, FALSE);
 
        return elev;
 }