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This commit is contained in:
Ivan Savenko 2023-01-14 23:01:33 +02:00
parent ccc6ebee0d
commit a46ab835ce
1 changed files with 24 additions and 15 deletions
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39
lib/battle/CBattleInfoCallback.cpp
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@ -163,33 +163,36 @@ struct Point
};
/// Algorithm to test whether line segment between points line1-line2 will intersect with
/// AABB (Axis-Aligned Bounding Box) defined by points aabb1 & aabb2
/// rectangle specified by top-left and bottom-right points
/// Note that in order to avoid floating point rounding errors algorithm uses integers with no divisions
static bool intersectionTestSegmentAABB(Point line1, Point line2, Point aabb1, Point aabb2)
static bool intersectionSegmentRect(Point line1, Point line2, Point rectTL, Point rectBR)
{
assert(rectTL.x < rectBR.x);
assert(rectTL.y < rectBR.y);
// check whether segment is located to the left of our AABB
if (line1.x < aabb1.x && line2.x < aabb1.x)
if (line1.x < rectTL.x && line2.x < rectTL.x)
return false;
// check whether segment is located to the right of our AABB
if (line1.x > aabb2.x && line2.x > aabb2.x)
if (line1.x > rectBR.x && line2.x > rectBR.x)
return false;
// check whether segment is located on top of our AABB
if (line1.y < aabb1.y && line2.y < aabb1.y)
if (line1.y < rectTL.y && line2.y < rectTL.y)
return false;
// check whether segment is located below of our AABB
if (line1.y > aabb2.y && line2.y > aabb2.y)
if (line1.y > rectBR.y && line2.y > rectBR.y)
return false;
Point vector { line2.x - line1.x, line2.y - line1.y};
// compute position of AABB corners relative to our line
int tlTest = vector.y*aabb1.x - vector.x*aabb1.y + (line2.x*line1.y-line1.x*line2.y);
int trTest = vector.y*aabb2.x - vector.x*aabb1.y + (line2.x*line1.y-line1.x*line2.y);
int blTest = vector.y*aabb1.x - vector.x*aabb2.y + (line2.x*line1.y-line1.x*line2.y);
int brTest = vector.y*aabb2.x - vector.x*aabb2.y + (line2.x*line1.y-line1.x*line2.y);
int tlTest = vector.y*rectTL.x - vector.x*rectTL.y + (line2.x*line1.y-line1.x*line2.y);
int trTest = vector.y*rectBR.x - vector.x*rectTL.y + (line2.x*line1.y-line1.x*line2.y);
int blTest = vector.y*rectTL.x - vector.x*rectBR.y + (line2.x*line1.y-line1.x*line2.y);
int brTest = vector.y*rectBR.x - vector.x*rectBR.y + (line2.x*line1.y-line1.x*line2.y);
// if all points are on the left of our line then there is no intersection
if ( tlTest > 0 && trTest > 0 && blTest > 0 && brTest > 0 )
@ -222,8 +225,13 @@ bool CBattleInfoCallback::battleHasWallPenalty(const IBonusBearer * shooter, Bat
auto needWallPenalty = [&](BattleHex from, BattleHex dest)
{
Point line1{ from.getX()*10+5, from.getY()*10+5};
Point line2{ dest.getX()*10+5, dest.getY()*10+5};
// arbitrary selected cell size for virtual grid
// any even number can be selected (for division by two)
static const int cellSize = 10;
// create line that goes from center of shooter cell to center of target cell
Point line1{ from.getX()*cellSize+cellSize/2, from.getY()*cellSize+cellSize/2};
Point line2{ dest.getX()*cellSize+cellSize/2, dest.getY()*cellSize+cellSize/2};
for (int y = 0; y < GameConstants::BFIELD_HEIGHT; ++y)
{
@ -231,10 +239,11 @@ bool CBattleInfoCallback::battleHasWallPenalty(const IBonusBearer * shooter, Bat
if (!isTileBlocked(obstacle))
continue;
Point aabb1{ obstacle.getX()*10, obstacle.getY()*10 };
Point aabb2{ aabb1.x + 10, aabb1.y + 10 };
// create rect around cell with an obstacle
Point rectTL{ obstacle.getX()*cellSize, obstacle.getY()*cellSize };
Point recrBR{ obstacle.getX()*(cellSize+1), obstacle.getY()*(cellSize+1) };
if ( intersectionTestSegmentAABB(line1, line2, aabb1, aabb2))
if ( intersectionSegmentRect(line1, line2, rectTL, recrBR))
return true;
}
return false;