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faster computation of entity bounding cube

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This commit is contained in:
Andrew Meadows 2017-07-19 13:35:34 -07:00
parent d9c6126000
commit 9ca3ec4313
1 changed files with 8 additions and 14 deletions
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22
libraries/entities/src/EntityItem.cpp
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@ -1423,26 +1423,20 @@ void EntityItem::setDimensions(const glm::vec3& value) {
///
AACube EntityItem::getMaximumAACube(bool& success) const {
if (_recalcMaxAACube) {
// * we know that the position is the center of rotation
glm::vec3 centerOfRotation = getPosition(success); // also where _registration point is
if (success) {
_recalcMaxAACube = false;
// * we know that the registration point is the center of rotation
// * we can calculate the length of the furthest extent from the registration point
// as the dimensions * max (registrationPoint, (1.0,1.0,1.0) - registrationPoint)
glm::vec3 dimensions = getDimensions();
glm::vec3 registrationPoint = (dimensions * _registrationPoint);
glm::vec3 registrationRemainder = (dimensions * (glm::vec3(1.0f, 1.0f, 1.0f) - _registrationPoint));
glm::vec3 furthestExtentFromRegistration = glm::max(registrationPoint, registrationRemainder);
// we want to compute the furthestExtent that an entity can extend out from its "position"
// to do this we compute the max of these two vec3s: registration and 1-registration
// and then scale by dimensions
glm::vec3 maxExtents = getDimensions() * glm::max(_registrationPoint, glm::vec3(1.0f) - _registrationPoint);
// * we know that if you rotate in any direction you would create a sphere
// that has a radius of the length of furthest extent from registration point
float radius = glm::length(furthestExtentFromRegistration);
// there exists a sphere that contains maxExtents for all rotations
float radius = glm::length(maxExtents);
// * we know that the minimum bounding cube of this maximum possible sphere is
// (center - radius) to (center + radius)
// put a cube around the sphere
// TODO? replace _maxAACube with _boundingSphereRadius
glm::vec3 minimumCorner = centerOfRotation - glm::vec3(radius, radius, radius);
_maxAACube = AACube(minimumCorner, radius * 2.0f);
}
} else {