Method IsInsideLineSegment

trinity/Sprite2d/Tr2Sprite2dScene.cpp:1448–1515

}

bool Tr2Sprite2dScene::IsInsideLineSegment( const Vector2& pointIn, const Vector2& start, const Vector2& end, float lineWidth )
{
	if( !IsInsideClipRect( pointIn ) )
	{
		return false;
	}

	Vector2 startTransformed;
	Vector2 endTransformed;

	if( m_transformStack->empty() )
	{
		startTransformed.x = start.x;
		startTransformed.y = start.y;
		endTransformed.x = end.x;
		endTransformed.y = end.y;
	}
	else
	{
		const TransformStackEntry& topEntry = m_transformStack->back();

		if( topEntry.isTranslationOnly )
		{
			startTransformed.x = start.x + topEntry.translation.x;
			startTransformed.y = start.y + topEntry.translation.y;
			endTransformed.x = end.x + topEntry.translation.x;
			endTransformed.y = end.y + topEntry.translation.y;
		}
		else
		{
			const Matrix& transform = topEntry.transform;

			TransformPoint( startTransformed, start, transform );
			TransformPoint( endTransformed, end, transform );
		}
	}

	// http://en.wikipedia.org/wiki/Distance_from_a_point_to_a_line

	float dx = endTransformed.x - startTransformed.x;
	float dy = endTransformed.y - startTransformed.y;

	float den = sqrtf( dx * dx + dy * dy );
	if( den < FLT_EPSILON )
	{
		return false;
	}

	float nom = fabs( dy * pointIn.x - dx * pointIn.y - startTransformed.x * endTransformed.y + startTransformed.y * endTransformed.x );
	float distance = nom / den;

	if( distance > lineWidth )
	{
		return false;
	}

	// Check that we are between the end points of the segment