/**
* Separating axis test; returns true if the square defined by u/v/halfSize at the origin
* is not entirely on the clockwise side of a line in direction 'axis' passing through 'a'
*/
static bool SquareSAT(const CFixedVector2D& a, const CFixedVector2D& axis, const CFixedVector2D& u, const CFixedVector2D& v, const CFixedVector2D& halfSize)
{
fixed hw = halfSize.X;
fixed hh = halfSize.Y;
CFixedVector2D p = axis.Perpendicular();
if (p.Dot((u.Multiply(hw) + v.Multiply(hh)) - a) <= fixed::Zero())
return true;
if (p.Dot((u.Multiply(hw) - v.Multiply(hh)) - a) <= fixed::Zero())
return true;
if (p.Dot((-u.Multiply(hw) - v.Multiply(hh)) - a) <= fixed::Zero())
return true;
if (p.Dot((-u.Multiply(hw) + v.Multiply(hh)) - a) <= fixed::Zero())
return true;
return false;
}
virtual CFixedVector3D PickSpawnPoint(entity_id_t spawned)
{
// Try to find a free space around the building's footprint.
// (Note that we use the footprint, not the obstruction shape - this might be a bit dodgy
// because the footprint might be inside the obstruction, but it hopefully gives us a nicer
// shape.)
const CFixedVector3D error(fixed::FromInt(-1), fixed::FromInt(-1), fixed::FromInt(-1));
CmpPtr<ICmpPosition> cmpPosition(GetSimContext(), GetEntityId());
if (!cmpPosition || !cmpPosition->IsInWorld())
return error;
CmpPtr<ICmpObstructionManager> cmpObstructionManager(GetSimContext(), SYSTEM_ENTITY);
if (!cmpObstructionManager)
return error;
entity_pos_t spawnedRadius;
ICmpObstructionManager::tag_t spawnedTag;
CmpPtr<ICmpObstruction> cmpSpawnedObstruction(GetSimContext(), spawned);
if (cmpSpawnedObstruction)
{
spawnedRadius = cmpSpawnedObstruction->GetUnitRadius();
spawnedTag = cmpSpawnedObstruction->GetObstruction();
}
// else use zero radius
// Get passability class from UnitMotion
CmpPtr<ICmpUnitMotion> cmpUnitMotion(GetSimContext(), spawned);
if (!cmpUnitMotion)
return error;
ICmpPathfinder::pass_class_t spawnedPass = cmpUnitMotion->GetPassabilityClass();
CmpPtr<ICmpPathfinder> cmpPathfinder(GetSimContext(), SYSTEM_ENTITY);
if (!cmpPathfinder)
return error;
CFixedVector2D initialPos = cmpPosition->GetPosition2D();
entity_angle_t initialAngle = cmpPosition->GetRotation().Y;
// Max spawning distance in tiles
const i32 maxSpawningDistance = 4;
if (m_Shape == CIRCLE)
{
// Expand outwards from foundation
for (i32 dist = 0; dist <= maxSpawningDistance; ++dist)
{
// The spawn point should be far enough from this footprint to fit the unit, plus a little gap
entity_pos_t clearance = spawnedRadius + entity_pos_t::FromInt(2 + (int)TERRAIN_TILE_SIZE*dist);
entity_pos_t radius = m_Size0 + clearance;
// Try equally-spaced points around the circle in alternating directions, starting from the front
const i32 numPoints = 31 + 2*dist;
for (i32 i = 0; i < (numPoints+1)/2; i = (i > 0 ? -i : 1-i)) // [0, +1, -1, +2, -2, ... (np-1)/2, -(np-1)/2]
{
entity_angle_t angle = initialAngle + (entity_angle_t::Pi()*2).Multiply(entity_angle_t::FromInt(i)/(int)numPoints);
fixed s, c;
sincos_approx(angle, s, c);
CFixedVector3D pos (initialPos.X + s.Multiply(radius), fixed::Zero(), initialPos.Y + c.Multiply(radius));
SkipTagObstructionFilter filter(spawnedTag); // ignore collisions with the spawned entity
if (cmpPathfinder->CheckUnitPlacement(filter, pos.X, pos.Z, spawnedRadius, spawnedPass) == ICmpObstruction::FOUNDATION_CHECK_SUCCESS)
return pos; // this position is okay, so return it
}
}
}
else
{
fixed s, c;
sincos_approx(initialAngle, s, c);
// Expand outwards from foundation
for (i32 dist = 0; dist <= maxSpawningDistance; ++dist)
{
// The spawn point should be far enough from this footprint to fit the unit, plus a little gap
entity_pos_t clearance = spawnedRadius + entity_pos_t::FromInt(2 + (int)TERRAIN_TILE_SIZE*dist);
for (i32 edge = 0; edge < 4; ++edge)
{
// Try equally-spaced points along the edge in alternating directions, starting from the middle
const i32 numPoints = 9 + 2*dist;
// Compute the direction and length of the current edge
CFixedVector2D dir;
fixed sx, sy;
switch (edge)
{
case 0:
dir = CFixedVector2D(c, -s);
sx = m_Size0;
sy = m_Size1;
break;
case 1:
dir = CFixedVector2D(-s, -c);
sx = m_Size1;
sy = m_Size0;
break;
case 2:
dir = CFixedVector2D(s, c);
sx = m_Size1;
sy = m_Size0;
break;
case 3:
dir = CFixedVector2D(-c, s);
sx = m_Size0;
sy = m_Size1;
break;
}
CFixedVector2D center = initialPos - dir.Perpendicular().Multiply(sy/2 + clearance);
dir = dir.Multiply((sx + clearance*2) / (int)(numPoints-1));
for (i32 i = 0; i < (numPoints+1)/2; i = (i > 0 ? -i : 1-i)) // [0, +1, -1, +2, -2, ... (np-1)/2, -(np-1)/2]
{
CFixedVector2D pos (center + dir*i);
SkipTagObstructionFilter filter(spawnedTag); // ignore collisions with the spawned entity
if (cmpPathfinder->CheckUnitPlacement(filter, pos.X, pos.Y, spawnedRadius, spawnedPass) == ICmpObstruction::FOUNDATION_CHECK_SUCCESS)
return CFixedVector3D(pos.X, fixed::Zero(), pos.Y); // this position is okay, so return it
}
}
}
}
return error;
}