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More functional decomposition and documentation.

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david 2002-07-17 22:11:13 +00:00
parent 5d2c640f1a
commit cc8567ad63
1 changed files with 93 additions and 56 deletions
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147
src/Objects/obj.cxx
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@ -347,6 +347,77 @@ add_object_to_triangle (sgVec3 p1, sgVec3 p2, sgVec3 p3, sgVec3 center,
}
/**
* Populate a single 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.
*
* @param leaf The leaf containing the data for the terrain surface.
* @param tri_index The index of the triangle in the leaf.
* @param mat The material data for the triangle.
* @param branch The branch to which the randomly-placed objects
* should be added.
* @param ROT A rotation matrix to align the objects with the earth's
* surface at the current lat/lon.
*/
static void
populate_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,
(p1[0] + p2[0] + p3[0]) / 3.0,
(p1[1] + p2[1] + p3[1]) / 3.0,
(p1[2] + p2[2] + p3[2]) / 3.0);
// Set up a transformation to the center
// point, so that everything else can
// be specified relative to it.
ssgTransform * location = new ssgTransform;
sgMat4 TRANS;
sgMakeTransMat4(TRANS, center);
location->setTransform(TRANS);
branch->addKid(location);
// Iterate through all the objects 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)};
ssgRangeSelector * lod = new ssgRangeSelector;
lod->setRanges(ranges, 2);
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 a rotation matrix to align an object for the current lat/lon.
*
@ -379,6 +450,20 @@ makeWorldUpRotationMatrix (sgMat4 ROT, double hdg_deg,
}
/**
* Randomly place objects on a surface.
*
* The leaf node provides the geometry of the surface, while the
* material provides the objects and placement density. Latitude
* and longitude are required so that the objects can be rotated
* to the world-up vector.
*
* @param leaf The surface where the objects should be placed.
* @param branch The branch that will hold the randomly-placed objects.
* @param lon_deg The longitude of the surface center, in degrees.
* @param lat_deg The latitude of the surface center, in degrees.
* @param material_name The name of the surface's material.
*/
static void
gen_random_surface_objects (ssgLeaf *leaf,
ssgBranch *branch,
@ -414,66 +499,18 @@ gen_random_surface_objects (ssgLeaf *leaf,
sgMat4 ROT;
makeWorldUpRotationMatrix(ROT, hdg_deg, lon_deg, lat_deg);
short int n1, n2, n3;
float *p1, *p2, *p3;
sgVec3 result;
// generate a repeatable random seed
p1 = leaf->getVertex( 0 );
unsigned int seed = (unsigned int)p1[0];
sg_srandom( seed );
sg_srandom((unsigned int)(leaf->getVertex(0)[0]));
// Iterate through all the triangles
// and populate them.
for ( int i = 0; i < num_tris; ++i ) {
short n1, n2, n3;
leaf->getTriangle(i, &n1, &n2, &n3);
p1 = leaf->getVertex(n1);
p2 = leaf->getVertex(n2);
p3 = leaf->getVertex(n3);
double area = sgTriArea( p1, p2, p3 );
// Set up a single center point for LOD
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);
// Set up a transformation to the center
// point, so that everything else can
// be specified relative to it.
ssgTransform * location = new ssgTransform;
sgMat4 TRANS;
sgMakeTransMat4(TRANS, center);
location->setTransform(TRANS);
branch->addKid(location);
// Iterate through all the objects.
for (int j = 0; j < num_objects; j++) {
double num = area / mat->get_object_coverage(j);
float ranges[] = {0, mat->get_object_lod(j)};
ssgRangeSelector * lod = new ssgRangeSelector;
lod->setRanges(ranges, 2);
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, j, 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, j, objects);
}
}
}
populate_triangle(leaf->getVertex(n1),
leaf->getVertex(n2),
leaf->getVertex(n3),
mat, branch, ROT);
}
}