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+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/////////////////////////////
+// Geometry.h
+// $Id: Geometry.h,v 1.2 2011/06/17 13:35:48 mbansal Exp $
+
+#pragma once
+#include "MosaicTypes.h"
+
+///////////////////////////////////////////////////////////////
+///////////////// BEG GLOBAL ROUTINES /////////////////////////
+///////////////////////////////////////////////////////////////
+
+
+inline double hypotSq(double a, double b)
+{
+ return ((a)*(a)+(b)*(b));
+}
+
+inline void ClipRect(double x, double y, BlendRect &brect)
+{
+ if (y < brect.bot) brect.bot = y;
+ if (y > brect.top) brect.top = y;
+ if (x < brect.lft) brect.lft = x;
+ if (x > brect.rgt) brect.rgt = x;
+}
+
+inline void ClipRect(BlendRect rrect, BlendRect &brect)
+{
+ if (rrect.bot < brect.bot) brect.bot = rrect.bot;
+ if (rrect.top > brect.top) brect.top = rrect.top;
+ if (rrect.lft < brect.lft) brect.lft = rrect.lft;
+ if (rrect.rgt > brect.rgt) brect.rgt = rrect.rgt;
+}
+
+// Clip x to be within [-border,width+border-1]
+inline void clipToSegment(int &x, int width, int border)
+{
+ if(x < -border)
+ x = -border;
+ else if(x >= width+border)
+ x = width + border - 1;
+}
+
+// Return true if x within [-border,width+border-1]
+inline bool inSegment(int x, int width, int border)
+{
+ return (x >= -border && x < width + border - 1);
+}
+
+inline void FindTriangleCentroid(double x0, double y0, double x1, double y1,
+ double x2, double y2,
+ double &mass, double &centX, double &centY)
+{
+ // Calculate the centroid of the triangle
+ centX = (x0 + x1 + x2) / 3.0;
+ centY = (y0 + y1 + y2) / 3.0;
+
+ // Calculate 2*Area for the triangle
+ if (y0 == y2)
+ {
+ if (x0 == x1)
+ {
+ mass = fabs((y1 - y0) * (x2 - x0)); // Special case 1a
+ }
+ else
+ {
+ mass = fabs((y1 - y0) * (x1 - x0)); // Special case 1b
+ }
+ }
+ else if (x0 == x2)
+ {
+ if (x0 == x1)
+ {
+ mass = fabs((x2 - x0) * (y2 - y0)); // Special case 2a
+ }
+ else
+ {
+ mass = fabs((x1 - x0) * (y2 - y0)); // Special case 2a
+ }
+ }
+ else if (x1 == x2)
+ {
+ mass = fabs((x1 - x0) * (y2 - y0)); // Special case 3
+ }
+ else
+ {
+ // Calculate line equation from x0,y0 to x2,y2
+ double dx = x2 - x0;
+ double dy = y2 - y0;
+ // Calculate the length of the side
+ double len1 = sqrt(dx * dx + dy * dy);
+ double m1 = dy / dx;
+ double b1 = y0 - m1 * x0;
+ // Calculate the line that goes through x1,y1 and is perpendicular to
+ // the other line
+ double m2 = 1.0 / m1;
+ double b2 = y1 - m2 * x1;
+ // Calculate the intersection of the two lines
+ if (fabs( m1 - m2 ) > 1.e-6)
+ {
+ double x = (b2 - b1) / (m1 - m2);
+ // the mass is the base * height
+ dx = x1 - x;
+ dy = y1 - m1 * x + b1;
+ mass = len1 * sqrt(dx * dx + dy * dy);
+ }
+ else
+ {
+ mass = fabs( (y1 - y0) * (x2 - x0) );
+ }
+ }
+}
+
+inline void FindQuadCentroid(double x0, double y0, double x1, double y1, double x2, double y2, double x3, double y3,
+ double &centX, double &centY)
+
+{
+ // To find the centroid:
+ // 1) Divide the quadrilateral into two triangles by scribing a diagonal
+ // 2) Calculate the centroid of each triangle (the intersection of the angle bisections).
+ // 3) Find the centroid of the quad by weighting each triangle centroids by their area.
+
+ // Calculate the corner points
+ double z;
+
+ // The quad is split from x0,y0 to x2,y2
+ double mass1, mass2, cent1x, cent2x, cent1y, cent2y;
+ FindTriangleCentroid(x0, y0, x1, y1, x2, y2, mass1, cent1x, cent1y);
+ FindTriangleCentroid(x0, y0, x3, y3, x2, y2, mass2, cent2x, cent2y);
+
+ // determine position of quad centroid
+ z = mass2 / (mass1 + mass2);
+ centX = cent1x + (cent2x - cent1x) * z;
+ centY = cent1y + (cent2y - cent1y) * z;
+}
+
+///////////////////////////////////////////////////////////////
+////////////////// END GLOBAL ROUTINES ////////////////////////
+///////////////////////////////////////////////////////////////
+
+