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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 ¢X, double ¢Y)
{
// 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 ¢X, double ¢Y)
{
// 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 ////////////////////////
///////////////////////////////////////////////////////////////
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