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Fix: Detect collision if one line is almost vertical (#5510) (#5531)

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bielern
2026-02-05 19:21:45 +01:00
committed by GitHub
parent f43e049444
commit 3881d2aac2
1 changed files with 20 additions and 20 deletions
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40
src/rshapes.c
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@ -2365,30 +2365,30 @@ bool CheckCollisionCircleRec(Vector2 center, float radius, Rectangle rec)
// Check the collision between two lines defined by two points each, returns collision point by reference
bool CheckCollisionLines(Vector2 startPos1, Vector2 endPos1, Vector2 startPos2, Vector2 endPos2, Vector2 *collisionPoint)
{
bool collision = false;
// According to https://en.wikipedia.org/wiki/Line–line_intersection#Given_two_points_on_each_line_segment
float rx = endPos1.x - startPos1.x;
float ry = endPos1.y - startPos1.y;
float sx = endPos2.x - startPos2.x;
float sy = endPos2.y - startPos2.y;
float div = (endPos2.y - startPos2.y)*(endPos1.x - startPos1.x) - (endPos2.x - startPos2.x)*(endPos1.y - startPos1.y);
float div = rx * sy - ry * sx;
if (fabsf(div) >= FLT_EPSILON)
{
collision = true;
float xi = ((startPos2.x - endPos2.x)*(startPos1.x*endPos1.y - startPos1.y*endPos1.x) - (startPos1.x - endPos1.x)*(startPos2.x*endPos2.y - startPos2.y*endPos2.x))/div;
float yi = ((startPos2.y - endPos2.y)*(startPos1.x*endPos1.y - startPos1.y*endPos1.x) - (startPos1.y - endPos1.y)*(startPos2.x*endPos2.y - startPos2.y*endPos2.x))/div;
if (((fabsf(startPos1.x - endPos1.x) > FLT_EPSILON) && (xi < fminf(startPos1.x, endPos1.x) || (xi > fmaxf(startPos1.x, endPos1.x)))) ||
((fabsf(startPos2.x - endPos2.x) > FLT_EPSILON) && (xi < fminf(startPos2.x, endPos2.x) || (xi > fmaxf(startPos2.x, endPos2.x)))) ||
((fabsf(startPos1.y - endPos1.y) > FLT_EPSILON) && (yi < fminf(startPos1.y, endPos1.y) || (yi > fmaxf(startPos1.y, endPos1.y)))) ||
((fabsf(startPos2.y - endPos2.y) > FLT_EPSILON) && (yi < fminf(startPos2.y, endPos2.y) || (yi > fmaxf(startPos2.y, endPos2.y))))) collision = false;
if (collision && (collisionPoint != 0))
{
collisionPoint->x = xi;
collisionPoint->y = yi;
}
if (fabsf(div) < FLT_EPSILON) {
return false;
}
return collision;
float s12x = startPos2.x - startPos1.x;
float s12y = startPos2.y - startPos1.y;
float t = (s12x * sy - s12y * sx) / div;
float u = (s12x * ry - s12y * rx) / div;
if (0.0f <= t && t <= 1.0f && 0.0f <= u && u <= 1.0f) {
collisionPoint->x = startPos1.x + t * rx;
collisionPoint->y = startPos1.y + t * ry;
return true;
}
return false;
}
// Check if point belongs to line created between two points [p1] and [p2] with defined margin in pixels [threshold]