Initial commit

engines/icb/common/px_2drealline.cpp

@@ -0,0 +1,133 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * Additional copyright for this file:
+ * Copyright (C) 1999-2000 Revolution Software Ltd.
+ * This code is based on source code created by Revolution Software,
+ * used with permission.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "engines/icb/common/px_2drealline.h"
+
+#include "math/utils.h"
+
+namespace ICB {
+
+typedef float PXfloat;
+typedef float PXreal;
+#define REAL_ZERO 0.0f
+#define REAL_TWO 2.0f
+#define REAL_MAX FLT_MAX
+
+px2DRealLine::IntersectionLogicVal px2DRealLine::Intersects(const px2DRealLine &oLineB, px2DRealPoint &oIntersection) const {
+	PXfloat fAX, fBX, fCX, fAY, fBY, fCY;
+	PXfloat fX1Low, fX1High, fY1Low, fY1High;
+	PXfloat fD, fE, fF;
+
+	// Initialize return value (costs little and tidies up code no end).
+	oIntersection.SetX(REAL_MAX);
+	oIntersection.SetY(REAL_MAX);
+
+	// Work out some commonly used terms.
+	fAX = m_fX2 - m_fX1;
+	fBX = oLineB.m_fX1 - oLineB.m_fX2;
+
+	// X bounding box test.
+	if (fAX < REAL_ZERO) {
+		fX1Low = m_fX2;
+		fX1High = m_fX1;
+	} else {
+		fX1High = m_fX2;
+		fX1Low = m_fX1;
+	}
+
+	if (fBX > REAL_ZERO) {
+		if ((fX1High < oLineB.m_fX2) || oLineB.m_fX1 < fX1Low)
+			return DONT_INTERSECT;
+	} else {
+		if ((fX1High < oLineB.m_fX1) || oLineB.m_fX2 < fX1Low)
+			return DONT_INTERSECT;
+	}
+
+	// More common terms.
+	fAY = m_fY2 - m_fY1;
+	fBY = oLineB.m_fY1 - oLineB.m_fY2;
+
+	// Y bounding box test.
+	if (fAY < REAL_ZERO) {
+		fY1Low = m_fY2;
+		fY1High = m_fY1;
+	} else {
+		fY1High = m_fY2;
+		fY1Low = m_fY1;
+	}
+
+	if (fBY > REAL_ZERO) {
+		if ((fY1High < oLineB.m_fY2) || oLineB.m_fY1 < fY1Low)
+			return DONT_INTERSECT;
+	} else {
+		if ((fY1High < oLineB.m_fY1) || oLineB.m_fY2 < fY1Low)
+			return DONT_INTERSECT;
+	}
+
+	// Couldn't dismiss the lines on their bounding rectangles, so do a proper intersection.
+	fCX = m_fX1 - oLineB.m_fX1;
+	fCY = m_fY1 - oLineB.m_fY1;
+
+	fD = (fBY * fCX) - (fBX * fCY);
+	fF = (fAY * fBX) - (fAX * fBY);
+
+	if (fF > REAL_ZERO) {
+		if ((fD < REAL_ZERO) || (fD > fF))
+			return DONT_INTERSECT;
+	} else {
+		if ((fD > REAL_ZERO) || (fD < fF))
+			return DONT_INTERSECT;
+	}
+
+	fE = (fAX * fCY) - (fAY * fCX);
+
+	if (fF > REAL_ZERO) {
+		if ((fE < REAL_ZERO) || (fE > fF))
+			return DONT_INTERSECT;
+	} else {
+		if ((fE > REAL_ZERO) || (fE < fF))
+			return DONT_INTERSECT;
+	}
+
+	// At this point, we can say that the lines do intersect as int32 as they are not
+	// colinear (colinear is indicated by fF == 0.0).
+	if (fabs(fF - REAL_ZERO) < (FLT_MIN * 10.0f))
+		return COLLINEAR;
+
+	// Right, lines do intersect, so calculate where.
+	PXfloat fNum, fOffset;
+	fNum = fD * fAX;
+	fOffset = SameSigns(fNum, fF) ? fF / REAL_TWO : -fF / REAL_TWO;
+	oIntersection.SetX(m_fX1 + (fNum + fOffset) / fF);
+
+	fNum = fD * fAY;
+	fOffset = SameSigns(fNum, fF) ? fF / REAL_TWO : -fF / REAL_TWO;
+	oIntersection.SetY(m_fY1 + (fNum + fOffset) / fF);
+
+	return DO_INTERSECT;
+}
+
+} // End of namespace ICB