PHP: imagepolygon

imagepolygon

(PHP 3, PHP 4, PHP 5)

imagepolygon -- Draw a polygon

Description

int imagepolygon ( resource image, array points, int num_points, int color )

imagepolygon() creates a polygon in image id. points is a PHP array containing the polygon's vertices, i.e. points[0] = x0, points[1] = y0, points[2] = x1, points[3] = y1, etc. num_points is the total number of points (vertices).

Example 1. imagepolygon() example

<?php // create a blank image $image = imagecreate(400, 300); // fill the background color $bg = imagecolorallocate($image, 0, 0, 0); // choose a color for the polygon $col_poly = imagecolorallocate($image, 255, 255, 255); // draw the polygon imagepolygon($image, array ( 0, 0, 100, 200, 300, 200 ), 3, $col_poly); // output the picture header("Content-type: image/png"); imagepng($image); ?>

User Contributed Notes
imagepolygon

jsnell at networkninja dot com
17-Feb-2001 09:07


Here are some handy routines for rotation and translation of polygons.  Scaling could be added easily as well.





function translate_point(&$x,&$y,$angle,$about_x,$about_y,$shift_x,$shift_y)


{


    $x -= $about_x;


    $y -= $about_y;


    $angle = ($angle / 180) * M_PI;


/* math:


[x2,y2] = [x,  *  [[cos(a),-sin(a)],


           y]      [sin(a),cos(a)]]


==>


x = x * cos(a) + y*sin(a) 


y = x*-sin(a) + y*cos(a)


*/





    $new_x = $x * cos($angle) - $y * sin($angle);


    $new_y = $x * sin($angle) + $y * cos($angle);


    $x = $new_x+ $about_x + $shift_x ;


    $y = $new_y + $about_y + $shift_y;


}





function translate_poly($point_array, $angle, $about_x, $about_y,$shift_x,$shift_y)


{


    $translated_poly = Array();


    while(count($point_array) > 1)


    {


        $temp_x = array_shift($point_array);


        $temp_y = array_shift($point_array);


        translate_point($temp_x, $temp_y, $angle, $about_x, $about_y,$shift_x, $shift_y);


        array_push($translated_poly, $temp_x);


        array_push($translated_poly, $temp_y);


    }


    return $translated_poly;


}

imagepng

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Last updated: Thu, 19 May 2005