<?php
/*------------------------------------------------------------------------------
** File: polyExample.php
** Description: Demo's the capability of the polygon class.
** Version: 1.3
** Author: Brenor Brophy
** Email: brenor dot brophy at gmail dot com
** Homepage: www.brenorbrophy.com
**------------------------------------------------------------------------------
** COPYRIGHT (c) 2005,2006 BRENOR BROPHY
**
** The source code included in this package 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. This license can be
** read at:
**
** http://www.opensource.org/licenses/gpl-license.php
**
** 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.
**------------------------------------------------------------------------------
**
** Based on the paper "Efficient Clipping of Arbitary Polygons" by Gunther
** Greiner (greiner at informatik dot uni-erlangen dot de) and Kai Hormann
** (hormann at informatik dot tu-clausthal dot de), ACM Transactions on Graphics
** 1998;17(2):71-83.
**
** Available at: www.in.tu-clausthal.de/~hormann/papers/clipping.pdf
**
** Another useful site describing the algorithm and with some example
** C code by Ionel Daniel Stroe is at:
**
** http://davis.wpi.edu/~matt/courses/clipping/
**
** The algorithm is extended by Brenor Brophy to allow polygons with
** arcs between vertices.
**
** Rev History
** -----------------------------------------------------------------------------
** 1.0 08/25/2005 Initial Release.
** 1.1 09/04/2005 Removed old html documentation from file.
** Added software license language to header comments.
** Added example code for new methods Move(),Rotate(),bRect()
** and isPolyInside().
** Added newImage() function to make the code a bit neater.
** 1.2 09/07/2005 Minor fix to v1p2/polygon.php - no change to this file
** 1.3 04/16/2006 Minor fix to v1p3/polygon.php
** Added example 6 - a test for the degenerate case where
** a vertex falls exactly on a line of the other polygon.
*/
require('polygon.php'); // Where all the good stuff is
/*
** A simple function that draws the polygons onto an image to demo the class
**
** $x,$y .. are an offset that will be added to all coordinates of the polygon
** $i .. an image created with the imagecreate function
** $p .. A polygon Object to be drawn (could be a list of polygons)
** $col .. An array of allocated colors for the image
** $c .. Index to the colors array - i.e. the draw color
**
** Real Angle 0 45 90 135 180 225 270 315 360
** imgarc Angle 360 315 270 225 180 135 90 45 0 (To draw real angle)
** Thus imagearc Angle = 360 - Real Angle
**
** If d == -1 the arc is Anti-Clockwise, d == 1 the arc is clockwise
**
** imagearc only draws clockwise arcs, so if we have an Anti-Clockwise arc we
** must reverse the order of start-angle and end-angle.
**
** images have their origin point (0,0) at the top left corner. However in
** real world math the origin is at the bottom left. This really only matters
** for arcs (determining clockwise or anti-clockwise). Thus the points in
** the polygon are assumed to exist in real world coordinates. Thus they
** are 'inverted' in the y-axis to plot them on the image.
*/
function drawPolyAt($x, $y, &$i, &$p, &$col, $c)
{
if ($i) $sy = imagesy($i); // Determine the height of the image in pixels
// All $y coords will be subtracted from this
if ($p) // If a polygon exists
do // For all polygons in the list
{
$v =& $p->getFirst(); // get the first vertex of the first polygon
do // For all vertices in this polygon
{
$n =& $v->Next(); // Get the next vertex
if ($v->d() == 0) // Check is this is an ARc segment
{ // It is a line
imageLine ($i,$x+$v->X(),$sy-($y+$v->Y()),$x+$n->X(),$sy-($y+$n->Y()),$col[$c]); // Draw a line vertex to vertex
}
else
{ // It is an Arc
$s = 360 - rad2deg ($p->angle($v->Xc(), $v->Yc(), $v->X(), $v->Y())); // Calc start angle
$e = 360 - rad2deg ($p->angle($v->Xc(), $v->Yc(), $n->X(), $n->Y())); // Calc end angle
$dia = 2*$p->dist($v->X(), $v->Y(), $v->Xc(), $v->Yc());
if ($v->d() == -1) // Clockwise
imagearc($i, $x+$v->Xc(), $sy-($y+$v->Yc()),$dia,$dia,$s,$e,$col[$c]);
else // Anti-Clockwise
imagearc($i, $x+$v->Xc(), $sy-($y+$v->Yc()),$dia,$dia,$e,$s,$col[$c]);
}
$v =& $n; // Move to next vertex
}
while ($v->id() != $p->first->id()); // Keep drawing until the last vertex
$p =& $p->NextPoly(); // Get the next polygon in the list
}
while ($p); // Keep drawing polygons as long as they exist
}
/*
** Function to create an image and allocate a color table to it
*/
function newImage($width, $height, &$i, &$col)
{
if($i)
imagedestroy($i); // Delete any old image
$i = imagecreate ($width,$height); // New image to draw our polygons
$col["wht"] = imagecolorallocate ($i, 255, 255, 255); // Allocate some colors
$col["blk"] = imagecolorallocate ($i, 0, 0, 0);
$col["red"] = imagecolorallocate ($i, 255,0,0);
$col["blu"] = imagecolorallocate ($i, 0,0,255);
$col["grn"] = imagecolorallocate ($i, 0,192,0);
$col["pur"] = imagecolorallocate ($i, 255,0,255);
}
//------------------------------------------------------------------------------
// First example re-creates the example in Figure 5 of the paper
//
$polyA =& new polygon(); // Create a new polygon and add some vertices to it
$polyA->addv( 16,131);
$polyA->addv( 71,166);
$polyA->addv(105,138);
$polyA->addv( 25, 63);
$polyA->addv(118, 75);
$polyB =& new polygon; // Create a second polygon with some more points
$polyB->addv( 9,155);
$polyB->addv( 88,134);
$polyB->addv( 80, 16);
$polyB->addv( 26, 92);
$polyB->addv( 42,129);
//
// THIS IS THE IMPORTANT BIT
//
$poly3 =& $polyA->boolean($polyB, "A&B");// A&B .. A AND B .. (A intersection B)
$poly4 =& $polyA->boolean($polyB, "A|B");// A|B .. A OR B .. (A union B)
$poly5 =& $polyA->boolean($polyB, "A\B");// A\B .. A - B
$poly6 =& $polyA->boolean($polyB, "B\A");// B\A .. B - A
//
// Output the results
//
newImage (600,200, $im, $colors); // Create a new image to draw our polygons
drawPolyAt(0, 0, $im, $polyA, $colors, "red");
drawPolyAt(0, 0, $im, $polyB, $colors, "grn");
drawPolyAt(120, 0, $im, $poly3, $colors, "blu");
drawPolyAt(240, 0, $im, $poly4, $colors, "blu");
drawPolyAt(360, 0, $im, $poly5, $colors,"blu");
drawPolyAt(480, 0, $im, $poly6, $colors, "blu");
imagestring ($im, 1, 55, 190, "A", $colors["red"]);
imagestring ($im, 1, 65, 190, "B", $colors["grn"]);
imagestring ($im, 1, 185, 190, "A&B", $colors["blu"]);
imagestring ($im, 1, 305, 190, "A|B", $colors["blu"]);
imagestring ($im, 1, 425, 190, "A\B", $colors["blu"]);
imagestring ($im, 1, 545, 190, "B\A", $colors["blu"]);
imageGif($im,"poly_ex1.gif"); // Save the image to a file
//------------------------------------------------------------------------------
// Second example shows how to handle more than two polygons
//
$polyA =& new polygon(); // Create a new polygon and add some vertices to it
$polyA->addv( 40, 40);
$polyA->addv( 80, 40);
$polyA->addv( 68,100);
$polyA->addv( 80,160);
$polyA->addv( 40,160);
$polyB =& new polygon; // Create a second polygon with some more points
$polyB->addv( 60, 60);
$polyB->addv(100, 60);
$polyB->addv(100,140);
$polyB->addv( 60,140);
$polyB->addv( 48,100);
$polyC =& new polygon; // Create a third polygon with some more points
$polyC->addv( 20,100);
$polyC->addv(120, 80);
$polyC->addv(110,100);
$polyC->addv(120,120);
//
// THIS IS THE IMPORTANT BIT
//
$poly3 =& $polyA->boolean($polyB, "A&B"); // All the magic happens here
$poly4 =& $poly3->boolean($polyC, "A|B"); // Now OR polyC with the result
//
// Output the results
//
newImage (400,200, $im, $colors); // Create a new image to draw our polygons
drawPolyAt(0, 0, $im, $polyA, $colors, "red");
drawPolyAt(0, 0, $im, $polyB, $colors, "grn");
drawPolyAt(120, 0, $im, $poly3, $colors, "blu");
drawPolyAt(120, 0, $im, $polyC, $colors, "pur");
drawPolyAt(240, 0, $im, $poly4, $colors, "blu");
imagestring ($im, 1, 55, 190, "A", $colors["red"]);
imagestring ($im, 1, 65, 190, "B", $colors["grn"]);
imagestring ($im, 1, 185, 190, "(A&B)", $colors["blu"]);
imagestring ($im, 1, 215, 190, "C", $colors["pur"]);
imagestring ($im, 1, 305, 190, "(A&B)|C", $colors["blu"]);
imageGif($im,"poly_ex2.gif");
//------------------------------------------------------------------------------
// Third example shows how arc segments work
//
$polyA =& new polygon(); // Create a new polygon and add some vertices to it
$polyA->addv( 60,110,60,60,-1); // Arc with center 60,90 Clockwise
$polyA->addv( 60, 10,60,60,-1);
$polyB =& new polygon(); // Create a new polygon and add some vertices to it
$polyB->addv(100, 60,110,60,-1);// Arc with center 100,140 Clockwise
$polyB->addv(120, 60,110,60,-1);
//
// THIS IS THE IMPORTANT BIT
//
$poly3 =& $polyA->boolean($polyB, "A&B");
$poly4 =& $polyA->boolean($polyB, "A|B");
$poly5 =& $polyA->boolean($polyB, "A\B");
$poly6 =& $polyA->boolean($polyB, "B\A");
//
// Output the results
//
newImage (600,140, $im, $colors); // Create a new image to draw our polygons
drawPolyAt(0, 20, $im, $polyA, $colors, "red");
drawPolyAt(0, 20, $im, $polyB, $colors, "grn");
drawPolyAt(120, 20, $im, $poly3, $colors, "blu");
drawPolyAt(240, 20, $im, $poly4, $colors, "blu");
drawPolyAt(360, 20, $im, $poly5, $colors, "blu");
drawPolyAt(480, 20, $im, $poly6, $colors, "blu");
imagestring ($im, 1, 55, 130, "A", $colors["red"]);
imagestring ($im, 1, 65, 130, "B", $colors["grn"]);
imagestring ($im, 1, 185, 130, "A&B", $colors["blu"]);
imagestring ($im, 1, 305, 130, "A|B", $colors["blu"]);
imagestring ($im, 1, 425, 130, "A\B", $colors["blu"]);
imagestring ($im, 1, 545, 130, "B\A", $colors["blu"]);
imageGif($im,"poly_ex3.gif");
//------------------------------------------------------------------------------
// This example shows how polygon the move, rotate and bRect methods work
//
$poly1 =& new polygon();
$poly1->addv(25,35);
$poly1->addv(12,47);
$poly1->addv(12,93,50,60,-1);
$poly1->addv(100,60);
$poly1->addv(75,35,50,35,-1);
newImage (600,120, $im, $colors); // Create a new image to draw our polygons
drawPolyAt(0, 0, $im, $poly1, $colors, "red"); // The starting polygon
// Polygon center is at 50,60
for ($i=0; $i<5; $i++)
{
$poly1->move(100,0); // Move it 100 right
$poly1->rotate(150+($i*100),60,deg2rad(-30)); // Rotate 30 degrees clockwise around its center
drawPolyAt(0, 0, $im, $poly1, $colors, "blu"); // Draw it again
$br = NULL; // Dont waste memory
$br =& $poly1->bRect(); // Get the Bounding Rectangle
drawPolyAt(0, 0, $im, $br, $colors, "grn"); // And draw that as well
}
imageGif($im,"poly_ex4.gif");
//------------------------------------------------------------------------------
// This example shows how the isPolyInside method works
//
// poly1 & poly2 show that arc segments are treated correctly. The function will
// return false even when all vertices are inside, but when part of the polygon
// is still outside (because it is and arc or intersects with an arc)
// poly3 & poly4 show the simpler case where teh function returns false because
// a vertex of the polygon is outside.
//
$poly1 =& new polygon();
$poly1->addv(0,0);
$poly1->addv(0,25,0,50,1);
$poly1->addv(0,75);
$poly1->addv(0,100);
$poly1->addv(100,100);
$poly1->addv(100,0);
$poly1->move(10,10);
$poly2 =& new polygon(); // poly2 does fit inside poly1
$poly2->addv(10,10);
$poly2->addv(10,20,0,50,1);
$poly2->addv(10,80);
$poly2->addv(10,90);
$poly2->addv(90,90);
$poly2->addv(90,10);
$poly2->move(10,10);
$poly3 =& new polygon();
$poly3->addv(0,0);
$poly3->addv(0,100);
$poly3->addv(100,100);
$poly3->addv(100,0);
$poly3->move(300,10);
$poly4 =& new polygon();
$poly4->addv(10,50);
$poly4->addv(10,90);
$poly4->addv(50,90);
$poly4->addv(50,50);
$poly4->move(300,10);
newImage (600,120, $im, $colors); // Create a new image to draw our polygons
drawPolyAt(0, 0, $im, $poly1, $colors, "blu"); // Draw the initial outer polygons
drawPolyAt(0, 0, $im, $poly3, $colors, "blu");
//
// Depending on result of isPolyInside(0 method draw the polygon in green (inside) or
// in red (NOT inside)
//
if ($poly1->isPolyInside($poly2)) // example 1
drawPolyAt(0, 0, $im, $poly2, $colors, "grn");
else
drawPolyAt(0, 0, $im, $poly2, $colors, "red");
if ($poly3->isPolyInside($poly4)) // example 2
drawPolyAt(0, 0, $im, $poly4, $colors, "grn"); // The starting polygon
else
drawPolyAt(0, 0, $im, $poly4, $colors, "red"); // The starting polygon
//
// Now move the 4 polygons and rotate the inner ones to cause them to fail
// the isPolyInside test
//
$poly1->move(150,0);
$poly2->move(150,0);
$poly2->rotate(210,60,deg2rad(90));
$poly3->move(150,0);
$poly4->move(150,0);
$poly4->rotate(500,60,deg2rad(45));
//
// Draw the polygons again. This time the inner polygons will be red because they fail
// isPolyInside test.
//
drawPolyAt(0, 0, $im, $poly1, $colors, "blu"); // Draw the initial outer polygons
drawPolyAt(0, 0, $im, $poly3, $colors, "blu");
if ($poly1->isPolyInside($poly2))
drawPolyAt(0, 0, $im, $poly2, $colors, "grn");
else
drawPolyAt(0, 0, $im, $poly2, $colors, "red");
if ($poly3->isPolyInside($poly4))
drawPolyAt(0, 0, $im, $poly4, $colors, "grn");
else
drawPolyAt(0, 0, $im, $poly4, $colors, "red");
imageGif($im,"poly_ex5.gif");
//------------------------------------------------------------------------------
// This example checks the degenerate case when the vertex of one polygon lies
// exactly one the edge of the other polygon.
//
$polyA =& new polygon(); // Create a new polygon and add some vertices to it
$polyA->addv(0,0);
$polyA->addv(0,80);
$polyA->addv(80,80);
$polyA->addv(80,0);
$polyB =& new polygon; // Create a second polygon with some more points
$polyB->addv(40,80);
$polyB->addv(80,40,80,80,1);
$polyB->addv(120,80);
$polyB->addv(80,80);
$polyB->addv(80,120);
//
// THIS IS THE IMPORTANT BIT
//
$poly3 =& $polyA->boolean($polyB, "A&B");// A&B .. A AND B .. (A intersection B)
$poly4 =& $polyA->boolean($polyB, "A|B");// A|B .. A OR B .. (A union B)
$poly5 =& $polyA->boolean($polyB, "A\B");
$poly6 =& $polyA->boolean($polyB, "B\A");
//
// Output the results
//
newImage (600,150, $im, $colors); // Create a new image to draw our polygons
drawPolyAt(0, 20, $im, $polyA, $colors, "red");
drawPolyAt(0, 20, $im, $polyB, $colors, "grn");
drawPolyAt(120, 20, $im, $poly3, $colors, "blu");
drawPolyAt(240, 20, $im, $poly4, $colors, "blu");
drawPolyAt(360, 20, $im, $poly5, $colors,"blu");
drawPolyAt(480, 20, $im, $poly6, $colors, "blu");
imagestring ($im, 1, 55, 140, "A", $colors["red"]);
imagestring ($im, 1, 65, 140, "B", $colors["grn"]);
imagestring ($im, 1, 185, 140, "A&B", $colors["blu"]);
imagestring ($im, 1, 305, 140, "A|B", $colors["blu"]);
imagestring ($im, 1, 425, 140, "A\B", $colors["blu"]);
imagestring ($im, 1, 545, 140, "B\A", $colors["blu"]);
imageGif($im,"poly_ex6.gif");
//
// Some links to diaplay the created images
//
echo '<div align="center"><strong>EXAMPLE 1</strong><br><img src="poly_ex1.gif" width="600" height="200"><br></div>';
echo '<div align="center"><strong>EXAMPLE 2</strong><br><img src="poly_ex2.gif" width="400" height="200"><br></div>';
echo '<div align="center"><strong>EXAMPLE 3</strong><br><img src="poly_ex3.gif" width="600" height="140"><br></div>';
echo '<div align="center"><strong>EXAMPLE 4</strong><br><img src="poly_ex4.gif" width="600" height="120"><br></div>';
echo '<div align="center"><strong>EXAMPLE 5</strong><br><img src="poly_ex5.gif" width="600" height="120"><br></div>';
echo '<div align="center"><strong>EXAMPLE 6</strong><br><img src="poly_ex6.gif" width="600" height="150"><br></div>';
?> |
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