/*
* Uses the technique described here:
* http://zeuxcg.org/2010/10/17/aabb-from-obb-with-component-wise-abs/
*/
void BoundingVolume::transform(const BoundingVolume &in_volume, glm::mat4 matrix) {
// Make sure the bounding volume itself is cleared before transformation
reset();
glm::vec3 center = (in_volume.min_corner() + in_volume.max_corner()) / 2.0f;
glm::vec3 extent = (in_volume.max_corner() - in_volume.min_corner()) / 2.0f;
for (int i = 0; i < 3; i++) {
for (int j = 0; j < 3; j++) {
scratch_abs_matrix[i, j] = abs(matrix[i, j]);
}
}
glm::vec4 new_center = matrix * glm::vec4(center, 1.0f);
glm::vec4 new_extent = scratch_abs_matrix * glm::vec4(extent, 0.0f);
glm::vec4 bb_min = new_center - new_extent;
glm::vec4 bb_max = new_center + new_extent;
expand(glm::vec3(bb_min.x, bb_min.y, bb_min.z));
expand(glm::vec3(bb_max.x, bb_max.y, bb_max.z));
}
void BoundingVolume::transform(const BoundingVolume &in_volume,
glm::mat4 matrix) {
// Make sure the bounding volume itself is cleared before transformation
reset();
glm::vec4 min_corner(in_volume.min_corner(), 1.0f);
glm::vec4 max_corner(in_volume.max_corner(), 1.0f);
glm::vec4 transformed_min_corner = matrix * min_corner;
glm::vec4 transformed_max_corner = matrix * max_corner;
glm::vec3 transformed_min(transformed_min_corner.x, transformed_min_corner.y,
transformed_min_corner.z);
glm::vec3 transformed_max(transformed_max_corner.x, transformed_max_corner.y,
transformed_max_corner.z);
// expand with the new corners
expand(transformed_min);
expand(transformed_max);
}
/*
* expand the volume by the incoming volume
*/
void BoundingVolume::expand(const BoundingVolume &volume) {
expand(volume.min_corner());
expand(volume.max_corner());
}
