[grits] Allow disabling operations in grits_object_draw

[Andy Spencer <andys src gnome org>]

commit 3ea7566fadf5490c46e04cb3a2a6cc8e02ac05e6
Author: Andy Spencer <andy753421 gmail com>
Date:   Sat Jan 22 20:13:05 2011 +0000

    Allow disabling operations in grits_object_draw
    
    Objects now include a GRITS_SKIP_* bitmask used for disabling various
    operations in grits_object_draw. The default is to perform all tests and
    operations, however some of these are expensive. Objects which do not
    need some operations or take care of it themselves can disable the tests
    in grits_object_draw to save processing time.
    
    For instance, saving the OpenGL state can be quite costly for simple
    objects.

 src/objects/grits-object.c |   74 +++++++++++++++++++++++++++++++------------
 src/objects/grits-object.h |    7 ++++
 2 files changed, 60 insertions(+), 21 deletions(-)
---
diff --git a/src/objects/grits-object.c b/src/objects/grits-object.c
index 12b4f8d..b321b6e 100644
--- a/src/objects/grits-object.c
+++ b/src/objects/grits-object.c
@@ -57,38 +57,67 @@ void grits_object_draw(GritsObject *object, GritsOpenGL *opengl)
 	if (object->hidden)
 		return;
 
-	/* Skip out of range objects */
-	if (object->lod > 0) {
+	/* Support GritsTester */
+	if (!GRITS_IS_OPENGL(opengl)) {
+		g_debug("GritsObject: draw - drawing raw object");
+		klass->draw(object, opengl);
+		return;
+	}
+
+	/* Calculae distance for LOD and horizon tests */
+	GritsPoint *center = &object->center;
+	if ((!(object->skip & GRITS_SKIP_LOD) ||
+	     !(object->skip & GRITS_SKIP_HORIZON)) &&
+	    (center->elev != -EARTH_R)) {
 		/* LOD test */
 		gdouble eye[3], obj[3];
-		grits_viewer_get_location(GRITS_VIEWER(opengl), &eye[0], &eye[1], &eye[2]);
+		grits_viewer_get_location(GRITS_VIEWER(opengl),
+				&eye[0], &eye[1], &eye[2]);
 		gdouble elev = eye[2];
-		lle2xyz(eye[0], eye[1], eye[2], &eye[0], &eye[1], &eye[2]);
-		lle2xyz(object->center.lat, object->center.lon, object->center.elev,
-			&obj[0], &obj[1], &obj[2]);
+		lle2xyz(eye[0], eye[1], eye[2],
+				&eye[0], &eye[1], &eye[2]);
+		lle2xyz(center->lat, center->lon, center->elev,
+				&obj[0], &obj[1], &obj[2]);
 		gdouble dist = distd(obj, eye);
-		if (object->lod < dist)
-			return;
-
-		/* Horizon testing */
-		gdouble c = EARTH_R+elev;
-		gdouble a = EARTH_R;
-		gdouble horizon = sqrt(c*c - a*a);
-		if (dist > horizon)
-			return;
+
+		/* Level of detail test */
+		if (!(object->skip & GRITS_SKIP_LOD)
+				&& object->lod > 0) {
+			if (object->lod < dist)
+				return;
+		}
+
+		/* Horizon test */
+		if (!(object->skip & GRITS_SKIP_HORIZON)) {
+			gdouble c = EARTH_R+elev;
+			gdouble a = EARTH_R;
+			gdouble horizon = sqrt(c*c - a*a);
+			if (dist > horizon)
+				return;
+		}
 	}
 
 	/* Save state, draw, restore state */
 	g_mutex_lock(opengl->sphere_lock);
-	glPushAttrib(GL_ALL_ATTRIB_BITS);
-	glMatrixMode(GL_PROJECTION); glPushMatrix();
-	glMatrixMode(GL_MODELVIEW);  glPushMatrix();
+	if (!(object->skip & GRITS_SKIP_STATE)) {
+		glPushAttrib(GL_ALL_ATTRIB_BITS);
+		glMatrixMode(GL_PROJECTION); glPushMatrix();
+		glMatrixMode(GL_MODELVIEW);  glPushMatrix();
+	}
+
+	if (!(object->skip & GRITS_SKIP_CENTER))
+		grits_viewer_center_position(GRITS_VIEWER(opengl),
+				object->center.lat,
+				object->center.lon,
+				object->center.elev);
 
 	klass->draw(object, opengl);
 
-	glPopAttrib();
-	glMatrixMode(GL_PROJECTION); glPopMatrix();
-	glMatrixMode(GL_MODELVIEW);  glPopMatrix();
+	if (!(object->skip & GRITS_SKIP_STATE)) {
+		glPopAttrib();
+		glMatrixMode(GL_PROJECTION); glPopMatrix();
+		glMatrixMode(GL_MODELVIEW);  glPopMatrix();
+	}
 	g_mutex_unlock(opengl->sphere_lock);
 }
 
@@ -102,6 +131,9 @@ void grits_object_queue_draw(GritsObject *object)
 G_DEFINE_ABSTRACT_TYPE(GritsObject, grits_object, G_TYPE_OBJECT);
 static void grits_object_init(GritsObject *object)
 {
+	object->center.lat  =  0;
+	object->center.lon  =  0;
+	object->center.elev = -EARTH_R;
 }
 
 static void grits_object_class_init(GritsObjectClass *klass)
diff --git a/src/objects/grits-object.h b/src/objects/grits-object.h
index 848319a..dcacd9d 100644
--- a/src/objects/grits-object.h
+++ b/src/objects/grits-object.h
@@ -30,6 +30,12 @@
 #define GRITS_IS_OBJECT_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE   ((klass), GRITS_TYPE_OBJECT))
 #define GRITS_OBJECT_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj),   GRITS_TYPE_OBJECT, GritsObjectClass))
 
+/* Bitmask of things to skip while drawing the object */
+#define GRITS_SKIP_LOD     (1<<0)
+#define GRITS_SKIP_HORIZON (1<<1)
+#define GRITS_SKIP_CENTER  (1<<2)
+#define GRITS_SKIP_STATE   (1<<3)
+
 typedef struct _GritsObject      GritsObject;
 typedef struct _GritsObjectClass GritsObjectClass;
 
@@ -41,6 +47,7 @@ struct _GritsObject {
 	GritsPoint   center; // Center of the object
 	gboolean     hidden; // If true, the object will not be drawn
 	gdouble      lod;    // Level of detail, used to hide small objects
+	guint32      skip;   // Bit mask of safe operations
 };
 
 struct _GritsObjectClass {