More functional decomposition and documentation.
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david
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1 changed files with 93 additions and 56 deletions
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@ -347,6 +347,77 @@ add_object_to_triangle (sgVec3 p1, sgVec3 p2, sgVec3 p3, sgVec3 center,
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}
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}
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/**
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* Populate a single triangle with randomly-placed objects.
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*
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* The objects and their density are defined in the material. If the
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* density is smaller than the minimum, there is an appropriate chance
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* of one appearing. The ssgBranch supplied will be populated
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* with the randomly-placed objects, with all objects of each type
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* under a range selector.
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*
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* @param leaf The leaf containing the data for the terrain surface.
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* @param tri_index The index of the triangle in the leaf.
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* @param mat The material data for the triangle.
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* @param branch The branch to which the randomly-placed objects
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* should be added.
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* @param ROT A rotation matrix to align the objects with the earth's
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* surface at the current lat/lon.
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*/
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static void
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populate_triangle (float * p1, float * p2, float * p3,
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FGNewMat * mat, ssgBranch * branch, sgMat4 ROT)
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{
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// Calculate the triangle area.
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double area = sgTriArea(p1, p2, p3);
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// Set up a single center point for LOD
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sgVec3 center;
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sgSetVec3(center,
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(p1[0] + p2[0] + p3[0]) / 3.0,
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(p1[1] + p2[1] + p3[1]) / 3.0,
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(p1[2] + p2[2] + p3[2]) / 3.0);
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// Set up a transformation to the center
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// point, so that everything else can
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// be specified relative to it.
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ssgTransform * location = new ssgTransform;
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sgMat4 TRANS;
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sgMakeTransMat4(TRANS, center);
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location->setTransform(TRANS);
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branch->addKid(location);
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// Iterate through all the objects types.
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int num_objects = mat->get_object_count();
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for (int i = 0; i < num_objects; i++) {
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double num = area / mat->get_object_coverage(i);
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float ranges[] = {0, mat->get_object_lod(i)};
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ssgRangeSelector * lod = new ssgRangeSelector;
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lod->setRanges(ranges, 2);
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location->addKid(lod);
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ssgBranch * objects = new ssgBranch;
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lod->addKid(objects);
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// place an object each unit of area
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while ( num > 1.0 ) {
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add_object_to_triangle(p1, p2, p3, center,
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ROT, mat, i, objects);
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num -= 1.0;
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}
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// for partial units of area, use a zombie door method to
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// create the proper random chance of an object being created
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// for this triangle
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if ( num > 0.0 ) {
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if ( sg_random() <= num ) {
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// a zombie made it through our door
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add_object_to_triangle(p1, p2, p3, center,
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ROT, mat, i, objects);
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}
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}
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}
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}
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/**
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/**
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* Create a rotation matrix to align an object for the current lat/lon.
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* Create a rotation matrix to align an object for the current lat/lon.
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*
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*
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@ -379,6 +450,20 @@ makeWorldUpRotationMatrix (sgMat4 ROT, double hdg_deg,
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}
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}
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/**
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* Randomly place objects on a surface.
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*
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* The leaf node provides the geometry of the surface, while the
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* material provides the objects and placement density. Latitude
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* and longitude are required so that the objects can be rotated
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* to the world-up vector.
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*
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* @param leaf The surface where the objects should be placed.
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* @param branch The branch that will hold the randomly-placed objects.
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* @param lon_deg The longitude of the surface center, in degrees.
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* @param lat_deg The latitude of the surface center, in degrees.
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* @param material_name The name of the surface's material.
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*/
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static void
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static void
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gen_random_surface_objects (ssgLeaf *leaf,
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gen_random_surface_objects (ssgLeaf *leaf,
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ssgBranch *branch,
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ssgBranch *branch,
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@ -414,66 +499,18 @@ gen_random_surface_objects (ssgLeaf *leaf,
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sgMat4 ROT;
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sgMat4 ROT;
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makeWorldUpRotationMatrix(ROT, hdg_deg, lon_deg, lat_deg);
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makeWorldUpRotationMatrix(ROT, hdg_deg, lon_deg, lat_deg);
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short int n1, n2, n3;
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float *p1, *p2, *p3;
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sgVec3 result;
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// generate a repeatable random seed
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// generate a repeatable random seed
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p1 = leaf->getVertex( 0 );
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sg_srandom((unsigned int)(leaf->getVertex(0)[0]));
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unsigned int seed = (unsigned int)p1[0];
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sg_srandom( seed );
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// Iterate through all the triangles
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// Iterate through all the triangles
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// and populate them.
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for ( int i = 0; i < num_tris; ++i ) {
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for ( int i = 0; i < num_tris; ++i ) {
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leaf->getTriangle( i, &n1, &n2, &n3 );
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short n1, n2, n3;
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p1 = leaf->getVertex(n1);
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leaf->getTriangle(i, &n1, &n2, &n3);
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p2 = leaf->getVertex(n2);
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populate_triangle(leaf->getVertex(n1),
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p3 = leaf->getVertex(n3);
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leaf->getVertex(n2),
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double area = sgTriArea( p1, p2, p3 );
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leaf->getVertex(n3),
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mat, branch, ROT);
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// Set up a single center point for LOD
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sgVec3 center;
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sgSetVec3(center,
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(p1[0] + p2[0] + p3[0]) / 3.0,
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(p1[1] + p2[1] + p3[1]) / 3.0,
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(p1[2] + p2[2] + p3[2]) / 3.0);
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// Set up a transformation to the center
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// point, so that everything else can
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// be specified relative to it.
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ssgTransform * location = new ssgTransform;
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sgMat4 TRANS;
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sgMakeTransMat4(TRANS, center);
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location->setTransform(TRANS);
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branch->addKid(location);
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// Iterate through all the objects.
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for (int j = 0; j < num_objects; j++) {
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double num = area / mat->get_object_coverage(j);
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float ranges[] = {0, mat->get_object_lod(j)};
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ssgRangeSelector * lod = new ssgRangeSelector;
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lod->setRanges(ranges, 2);
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location->addKid(lod);
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ssgBranch * objects = new ssgBranch;
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lod->addKid(objects);
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// place an object each unit of area
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while ( num > 1.0 ) {
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add_object_to_triangle(p1, p2, p3, center,
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ROT, mat, j, objects);
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num -= 1.0;
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}
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// for partial units of area, use a zombie door method to
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// create the proper random chance of an object being created
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// for this triangle
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if ( num > 0.0 ) {
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if ( sg_random() <= num ) {
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// a zombie made it through our door
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add_object_to_triangle(p1, p2, p3, center,
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ROT, mat, j, objects);
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}
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}
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}
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}
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}
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}
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}
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