branch->addKid(pos);
}
+class RandomObjectUserData : public ssgBase
+{
+public:
+ bool is_filled_in;
+ float * p1;
+ float * p2;
+ float * p3;
+ FGNewMat * mat;
+ int object_index;
+ ssgBranch * branch;
+ sgMat4 ROT;
+};
+
/**
- * Populate a single triangle with randomly-placed objects.
+ * Fill in a triangle with randomly-placed objects.
*
- * The objects and their density are defined in the material. If the
- * density is smaller than the minimum, there is an appropriate chance
- * of one appearing. The ssgBranch supplied will be populated
- * with the randomly-placed objects, with all objects of each type
- * under a range selector.
+ * This method is invoked by a callback when the triangle is in range
+ * but not yet populated.
+ *
+ * @param p1 The first vertex of the triangle.
+ * @param p2 The second vertex of the triangle.
+ * @param p3 The third vertex of the triangle.
+ * @param mat The triangle's material.
+ * @param object_index The index of the random object in the triangle.
+ * @param branch The branch where the objects should be added.
+ * @param ROT The rotation matrix to align objects with the earth's
+ * surface.
+ */
+static void
+fill_in_triangle (float * p1, float * p2, float * p3, FGNewMat * mat,
+ int object_index, ssgBranch * branch, sgMat4 ROT)
+{
+ sgVec3 center;
+ sgSetVec3(center,
+ (p1[0] + p2[0] + p3[0]) / 3.0,
+ (p1[1] + p2[1] + p3[1]) / 3.0,
+ (p1[2] + p2[2] + p3[2]) / 3.0);
+ double area = sgTriArea(p1, p2, p3);
+ double num = area / mat->get_object_coverage(object_index);
+
+ // place an object each unit of area
+ while ( num > 1.0 ) {
+ add_object_to_triangle(p1, p2, p3, center,
+ ROT, mat, object_index, branch);
+ num -= 1.0;
+ }
+ // for partial units of area, use a zombie door method to
+ // create the proper random chance of an object being created
+ // for this triangle
+ if ( num > 0.0 ) {
+ if ( sg_random() <= num ) {
+ // a zombie made it through our door
+ add_object_to_triangle(p1, p2, p3, center,
+ ROT, mat, object_index, branch);
+ }
+ }
+}
+
+
+/**
+ * SSG callback for an in-range triangle of randomly-placed objects.
+ *
+ * This pretraversal callback is attached to a branch that is traversed
+ * only when a triangle is in range. If the triangle is not currently
+ * populated with randomly-placed objects, this callback will populate
+ * it.
+ *
+ * @param entity The entity to which the callback is attached (not used).
+ * @param mask The entity's traversal mask (not used).
+ * @return Always 1, to allow traversal and culling to continue.
+ */
+static int
+in_range_callback (ssgEntity * entity, int mask)
+{
+ RandomObjectUserData * data = (RandomObjectUserData *)entity->getUserData();
+ if (!data->is_filled_in) {
+ fill_in_triangle(data->p1, data->p2, data->p3, data->mat,
+ data->object_index, data->branch, data->ROT);
+ data->is_filled_in = true;
+ }
+ return 1;
+}
+
+
+/**
+ * SSG callback for an out-of-range triangle of randomly-placed objects.
+ *
+ * This pretraversal callback is attached to a branch that is traversed
+ * only when a triangle is out of range. If the triangle is currently
+ * populated with randomly-placed objects, the objects will be removed.
+ *
+ *
+ * @param entity The entity to which the callback is attached (not used).
+ * @param mask The entity's traversal mask (not used).
+ * @return Always 0, to prevent any further traversal or culling.
+ */
+static int
+out_of_range_callback (ssgEntity * entity, int mask)
+{
+ RandomObjectUserData * data = (RandomObjectUserData *)entity->getUserData();
+ if (data->is_filled_in) {
+ data->branch->removeAllKids();
+ data->is_filled_in = false;
+ }
+ return 0;
+}
+
+
+/**
+ * ssgEntity pre-traversal callback to skip a culling test.
+ *
+ * This is necessary so that the in-range/out-of-range callbacks will
+ * be reached even when there is no leaf data underneath.
+ *
+ * @param entity The entity originating the callback (not used).
+ * @param mask The entity's traversal mask (not used).
+ * @return Always 2 to allow traversal without a cull test.
+ */
+static int
+notest_callback (ssgEntity * entity, int mask)
+{
+ return 2;
+}
+
+
+/**
+ * Set up a triangle for randomly-placed objects.
+ *
+ * No objects will be added unless the triangle comes into range.
*
* @param leaf The leaf containing the data for the terrain surface.
* @param tri_index The index of the triangle in the leaf.
* surface at the current lat/lon.
*/
static void
-populate_triangle (float * p1, float * p2, float * p3,
+setup_triangle (float * p1, float * p2, float * p3,
FGNewMat * mat, ssgBranch * branch, sgMat4 ROT)
{
- // Calculate the triangle area.
- double area = sgTriArea(p1, p2, p3);
-
// Set up a single center point for LOD
sgVec3 center;
sgSetVec3(center,
sgMat4 TRANS;
sgMakeTransMat4(TRANS, center);
location->setTransform(TRANS);
+ location->setTravCallback(SSG_CALLBACK_PRETRAV, notest_callback);
branch->addKid(location);
- // Iterate through all the objects types.
+ // Calculate the triangle area.
+ double area = sgTriArea(p1, p2, p3);
+
+ // Iterate through all the object types.
int num_objects = mat->get_object_count();
for (int i = 0; i < num_objects; i++) {
- double num = area / mat->get_object_coverage(i);
- float ranges[] = {0, mat->get_object_lod(i)};
+
+ // Set up the range selector. Note that
+ // we provide only two ranges, so the
+ // upper limit will be infinity.
+ float ranges[] = {0, mat->get_object_lod(i), 9999999};
ssgRangeSelector * lod = new ssgRangeSelector;
- lod->setRanges(ranges, 2);
+ lod->setRanges(ranges, 3);
+ lod->setTravCallback(SSG_CALLBACK_PRETRAV, notest_callback);
location->addKid(lod);
- ssgBranch * objects = new ssgBranch;
- lod->addKid(objects);
-
- // place an object each unit of area
- while ( num > 1.0 ) {
- add_object_to_triangle(p1, p2, p3, center,
- ROT, mat, i, objects);
- num -= 1.0;
- }
- // for partial units of area, use a zombie door method to
- // create the proper random chance of an object being created
- // for this triangle
- if ( num > 0.0 ) {
- if ( sg_random() <= num ) {
- // a zombie made it through our door
- add_object_to_triangle(p1, p2, p3, center,
- ROT, mat, i, objects);
- }
- }
+
+ // Create the in-range and out-of-range
+ // branches.
+ ssgBranch * in_range = new ssgBranch;
+ ssgBranch * out_of_range = new ssgBranch;
+
+ // Set up the user data for if/when
+ // the random objects in this triangle
+ // are filled in.
+ RandomObjectUserData * data = new RandomObjectUserData;
+ data->is_filled_in = false;
+ data->p1 = p1;
+ data->p2 = p2;
+ data->p3 = p3;
+ data->mat = mat;
+ data->object_index = i;
+ data->branch = in_range;
+ sgCopyMat4(data->ROT, ROT);
+
+ // Set up the in-range node.
+ in_range->setUserData(data);
+ in_range->setTravCallback(SSG_CALLBACK_PRETRAV,
+ in_range_callback);
+ lod->addKid(in_range);
+
+ // Set up the out-of-range node.
+ out_of_range->setUserData(data);
+ out_of_range->setTravCallback(SSG_CALLBACK_PRETRAV,
+ out_of_range_callback);
+ lod->addKid(out_of_range);
}
}
for ( int i = 0; i < num_tris; ++i ) {
short n1, n2, n3;
leaf->getTriangle(i, &n1, &n2, &n3);
- populate_triangle(leaf->getVertex(n1),
- leaf->getVertex(n2),
- leaf->getVertex(n3),
- mat, branch, ROT);
+ setup_triangle(leaf->getVertex(n1),
+ leaf->getVertex(n2),
+ leaf->getVertex(n3),
+ mat, branch, ROT);
}
}
projects / flightgear.git / commitdiff