Unit selection from screen coordinates
Posted: Sun Mar 10, 2019 1:41 am
looking for some help selecting units.
assume a 3d world with a top down camera, user presses LMouse to start selection rectangle and when LMouse is released we have a screen area highlighted.
if I use getRayFromScreenCoordinates then the ray is from the camera through the screen point and ends up not directly under the screen point but rather angled through the screen point.
how would I calculate a line that goes straight down through the corners of the screen selection rectangle?
I would then create an aabbox3d<f32> m_SelectionBox; that I can test units against to see if they were selected.
current attempt looks like this...
assume a 3d world with a top down camera, user presses LMouse to start selection rectangle and when LMouse is released we have a screen area highlighted.
if I use getRayFromScreenCoordinates then the ray is from the camera through the screen point and ends up not directly under the screen point but rather angled through the screen point.
how would I calculate a line that goes straight down through the corners of the screen selection rectangle?
I would then create an aabbox3d<f32> m_SelectionBox; that I can test units against to see if they were selected.
current attempt looks like this...
Code: Select all
virtual bool onLMouseButtonUp(const SEvent & e)
{
if (m_Selecting)
{
if (getLevel())
{
m_SelectedObjects.clear();
line3df l1 = getLevel()->getCollisionManager()->getRayFromScreenCoordinates(vector2di(m_ScreenSelectionArea.UpperLeftCorner.X, m_ScreenSelectionArea.UpperLeftCorner.Y));
line3df l2 = getLevel()->getCollisionManager()->getRayFromScreenCoordinates(vector2di(m_ScreenSelectionArea.LowerRightCorner.X, m_ScreenSelectionArea.LowerRightCorner.Y));
float BOX_DEPTH = 1000;
m_SelectionBox.MinEdge.set(vector3df(l1.end.X, -BOX_DEPTH, l1.end.Z));
m_SelectionBox.MaxEdge.set(vector3df(l2.end.X, BOX_DEPTH, l2.end.Z));
getLevel()->selectObjectsInArea(m_SelectionBox, FSOT_CHARACTER, m_SelectedObjects);
}
}
m_Selecting = false;
for (int x = 0; x < m_SelectedObjects.size(); x++) printf("Object in list %d\n",m_SelectedObjects[x]);
return false;
}