fix a rendering regression added in 9b165c1346

Signed-off-by: Sébastien Boisvert <sebastien.boisvert.3@ulaval.ca>
fix a quadtree rendering regression added in 9b165c1346a

Signed-off-by: Sébastien Boisvert <sebastien.boisvert.3@ulaval.ca>
perform reverse geometrical transformations to query index

Signed-off-by: Sébastien Boisvert <sebastien.boisvert.3@ulaval.ca>
increase gravitational pressure

Signed-off-by: Sébastien Boisvert <sebastien.boisvert.3@ulaval.ca>