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Change random object placement to a grid-like scheme to reduce building overlap.

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This commit is contained in:
Stuart Buchanan
2012-04-28 19:58:09 +01:00
parent f712bc9294
commit 1041445a22
1 changed files with 63 additions and 25 deletions
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88
simgear/scene/tgdb/obj.cxx
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@@ -506,18 +506,19 @@ struct SGTileGeometryBin {
int triangle_dropped = 0;
int building_dropped = 0;
int random_dropped = 0;
int mask_dropped = 0;
for (unsigned i = 0; i < num; ++i) {
SGBuildingBin::BuildingList triangle_buildings;
SGTexturedTriangleBin::triangle_ref triangleRef = triangleBin.getTriangleRef(i);
SGVec3f v0 = triangleBin.getVertex(triangleRef[0]).vertex;
SGVec3f v1 = triangleBin.getVertex(triangleRef[1]).vertex;
SGVec3f v2 = triangleBin.getVertex(triangleRef[2]).vertex;
SGVec2f t0 = triangleBin.getVertex(triangleRef[0]).texCoord;
SGVec2f t1 = triangleBin.getVertex(triangleRef[1]).texCoord;
SGVec2f t2 = triangleBin.getVertex(triangleRef[2]).texCoord;
SGVec3f normal = cross(v1 - v0, v2 - v0);
SGVec3f vorigin = triangleBin.getVertex(triangleRef[0]).vertex;
SGVec3f v0 = triangleBin.getVertex(triangleRef[1]).vertex - vorigin;
SGVec3f v1 = triangleBin.getVertex(triangleRef[2]).vertex - vorigin;
SGVec2f torigin = triangleBin.getVertex(triangleRef[0]).texCoord;
SGVec2f t0 = triangleBin.getVertex(triangleRef[1]).texCoord - torigin;
SGVec2f t1 = triangleBin.getVertex(triangleRef[2]).texCoord - torigin;
SGVec3f normal = cross(v0, v1);
// Compute the area
float area = 0.5f*length(normal);
@@ -528,34 +529,66 @@ struct SGTileGeometryBin {
// create the proper random chance of an object being created
// for this triangle.
double num = area / coverage + mt_rand(&seed);
if (num < 1.0f) {
continue;
}
// Apply density, which is linear, while we're dealing in areas
num = num * building_density * building_density;
// Apply density.
num = num * building_density;
// Cosine of the angle between the two vectors.
float cosine = (dot(v0, v1) / (length(v0) * length(v1)));
// place an object each unit of area
// Determine a grid spacing in each vector such that the correct
// coverage will result.
float stepv0 = (sqrtf(coverage) / building_density) / length(v0) / sqrtf(1 - cosine * cosine);
float stepv1 = (sqrtf(coverage) / building_density) / length(v1);
stepv0 = std::min(stepv0, 1.0f);
stepv1 = std::min(stepv1, 1.0f);
// Start at a random point. a will be immediately incremented below.
float a = -mt_rand(&seed) * stepv0;
float b = mt_rand(&seed) * stepv1;
// Place an object each unit of area
while ( num > 1.0 ) {
float a = mt_rand(&seed);
float b = mt_rand(&seed);
if ( a + b > 1 ) {
a = 1 - a;
b = 1 - b;
// Set the next location to place a building
a += stepv0;
if ( a + b > 1.0f ) {
// Reached the end of the scan-line on v0. Reset and increment
// scan-line on v1
a = mt_rand(&seed) * stepv0;
b += stepv1;
}
float c = 1 - a - b;
SGVec3f randomPoint = a*v0 + b*v1 + c*v2;
if (b > 1.0f) {
// In a degenerate case of a single point, we might be outside the
// scanline.
b = mt_rand(&seed) * stepv1;
}
SGVec3f randomPoint = vorigin + a*v0 + b*v1;
float rotation = mt_rand(&seed);
if (object_mask != NULL) {
SGVec2f texCoord = a*t0 + b*t1 + c*t2;
SGVec2f texCoord = torigin + a*t0 + b*t1;
osg::Image* img = object_mask->getImage();
unsigned int x = (int) (img->s() * texCoord.x()) % img->s();
unsigned int y = (int) (img->t() * texCoord.y()) % img->t();
int x = (int) (img->s() * texCoord.x()) % img->s();
int y = (int) (img->t() * texCoord.y()) % img->t();
// In some degenerate cases x or y can be < 1, in which case the mod operand fails
while (x < 0) x += img->s();
while (y < 0) y += img->t();
if (mt_rand(&seed) < img->getColor(x, y).b()) {
// Object passes mask. Rotation is taken from the red channel
rotation = img->getColor(x,y).r();
} else {
// Fails mask test - try again.
mask_dropped++;
num -= 1.0;
continue;
}
@@ -610,9 +643,11 @@ struct SGTileGeometryBin {
// Check that the point is sufficiently far from
// the edge of the triangle by measuring the distance
// from the three lines that make up the triangle.
if (((length(cross(randomPoint - v0, randomPoint - v1)) / length(v1 - v0)) < radius) ||
((length(cross(randomPoint - v1, randomPoint - v2)) / length(v2 - v1)) < radius) ||
((length(cross(randomPoint - v2, randomPoint - v0)) / length(v0 - v2)) < radius) )
SGVec3f p = randomPoint - vorigin;
if (((length(cross(p , p - v0)) / length(v0)) < radius) ||
((length(cross(p - v0, p - v1)) / length(v1 - v0)) < radius) ||
((length(cross(p - v1, p )) / length(v1)) < radius) )
{
triangle_dropped++;
num -= 1.0;
@@ -672,8 +707,9 @@ struct SGTileGeometryBin {
rotation,
pitched);
triangle_buildings.push_back(building);
num -= 1.0;
}
}
// Add the buildings from this triangle to the overall list.
SGBuildingBin::BuildingList::iterator l;
@@ -682,8 +718,9 @@ struct SGTileGeometryBin {
bin->insert(*l);
}
}
SG_LOG(SG_INPUT, SG_DEBUG, "Random Buildings: " << bin->getNumBuildings());
SG_LOG(SG_INPUT, SG_DEBUG, " Dropped due to mask: " << mask_dropped);
SG_LOG(SG_INPUT, SG_DEBUG, " Dropped due to triangle edge: " << triangle_dropped);
SG_LOG(SG_INPUT, SG_DEBUG, " Dropped due to random object: " << random_dropped);
SG_LOG(SG_INPUT, SG_DEBUG, " Dropped due to other building: " << building_dropped);
@@ -696,6 +733,7 @@ struct SGTileGeometryBin {
// generate a repeatable random seed
mt seed;
mt_init(&seed, unsigned(586));
for (i = materialTriangleMap.begin(); i != materialTriangleMap.end(); ++i) {