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PHP : Function Reference : Image Functions : imagefilledpolygon

imagefilledpolygon

Draw a filled polygon (PHP 4, PHP 5)
bool imagefilledpolygon ( resource image, array points, int num_points, int color )

Example 1010. imagefilledpolygon() example

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<?php
// set up array of points for polygon
$values = array(
           40,  50,  // Point 1 (x, y)
           20,  240, // Point 2 (x, y)
           60,  60,  // Point 3 (x, y)
           240, 20,  // Point 4 (x, y)
           50,  40,  // Point 5 (x, y)
           10,  10   // Point 6 (x, y)
           );

// create image
$image = imagecreatetruecolor(250, 250);

// some colors
$bg   = imagecolorallocate($image, 200, 200, 200);
$blue = imagecolorallocate($image, 0, 0, 255);

// draw a polygon
imagefilledpolygon($image, $values, 6, $blue);

// flush image
header('Content-type: image/png');
imagepng($image);
imagedestroy($image);
?>

The above example will output something similar to:


Related Examples ( Source code ) » imagefilledpolygon

Examples ( Source code ) » Making Colors Transparent with imagecolortransparent()
Examples ( Source code ) » Drawing a Triangler
Examples ( Source code ) » Drawing a Polygon with imagefilledpolygon()

Code Examples / Notes » imagefilledpolygon

etnekor
There is a simple function to draw a filled point with a chosen radius and color.
<?php
function drawPoint($img, $radius, $origo_x, $origo_y, $pointColor)
{
 for ($i=0;$i<=360;$i++)
 {
   $pont[] = $origo_x + ($radius * sin(deg2rad($i)));
   $pont[] = $origo_y - ($radius * cos(deg2rad($i)));
 }
 reset($pont);
 ImageFilledPolygon ($img, $pont, (sizeof($pont)/2), $pointColor);
}
?>

webmaster
Just thought that 'tatlar at yahoo dot com's function has some redundant code in it, so I tried to "improve" it. Now you can choose a variable number of spikes.
<?php
error_reporting(E_ALL);
function drawStar($x, $y, $radius, $spikes=5) {
   // $x, $y -> Position in the image
   // $radius -> Radius of the star
   // $spikes -> Number of spikes
   $coordinates = array();
   $angel = 360 / $spikes ;
   // Get the coordinates of the outer shape of the star
   $outer_shape = array();
   for($i=0; $i<$spikes; $i++){
    $outer_shape[$i]['x'] = $x + ($radius * cos(deg2rad(270 - $angel*$i)));
    $outer_shape[$i]['y'] = $y + ($radius * sin(deg2rad(270 - $angel*$i)));
   }
   // Get the coordinates of the inner shape of the star
   $inner_shape = array();
   for($i=0; $i<$spikes; $i++){
    $inner_shape[$i]['x'] = $x + (0.5*$radius * cos(deg2rad(270-180 - $angel*$i)));
    $inner_shape[$i]['y'] = $y + (0.5*$radius * sin(deg2rad(270-180 - $angel*$i)));
   }
   // Bring the coordinates in the right order
   foreach($inner_shape as $key => $value){
    if($key == (floor($spikes/2)+1))
        break;
    $inner_shape[] = $value;
    unset($inner_shape[$key]);
   }
   // Reset the keys
   $i=0;
   foreach($inner_shape as $value){
    $inner_shape[$i] = $value;
    $i++;
   }
   // "Merge" outer and inner shape
   foreach($outer_shape as $key => $value){
        $coordinates[] = $outer_shape[$key]['x'];
        $coordinates[] = $outer_shape[$key]['y'];
        $coordinates[] = $inner_shape[$key]['x'];
        $coordinates[] = $inner_shape[$key]['y'];
   }
   // Return the coordinates
   return $coordinates ;
}
// Example
$spikes = 5;
$values = drawStar(250, 250, 200, $spikes);
$im = imagecreate(500,500);
imagecolorallocate($im,0,0,0);
$w = imagecolorallocate($im, 255, 255, 255);
imagefilledpolygon($im, $values, $spikes*2, $w);
imageGIF($im);
imagedestroy($im);
?>

jylyn
In spite of what it says about requiring more than 3 vertices, it is possible to draw a triangle with this function!

arnapou
I discovered that the GD imagefilledpolygon function is incorrect for some drawing with transparent color (for example red 50% : RGBA = 255, 0, 0, 64).
I tried to draw a complex form with lots of points really near (1 pixel of distance) and a transparent red.
The problem was : some border pixels were not drawn by the imagefilledpolygon but were drawn with imagepolygon !?!?
So I wrote my own imagefilledpolygon function which work very well in all case I tested.
<?php
// $points should be an array of coordinates like that :
$points = array(
array(0, 0),
array(100, 50),
array(90, 100),
array(50, 50),
array(70, 30),
array(10, 10),
);
?>
<?php
function myimagefilledpolygon(& $img, $points, $color) {
$scanline = 99999;
// compute edges
$all_edges = array();
$n = count($points);
for($i=0; $i<$n; $i++) {
$p1 = $points[$i];
if ($i == $n-1) { $p2 = $points[0]; } else { $p2 = $points[$i+1]; }
$x1 = $p1[0]; $y1 = $p1[1];
$x2 = $p2[0]; $y2 = $p2[1];
if ($y1 != $y2) {
$invslope = ($x2 - $x1)/($y2 - $y1);
if ($y1 < $y2 ) {
$ymin = $y1;
$xval = $x1;
$ymax = $y2;
} else {
$ymin = $y2;
$xval = $x2;
$ymax = $y1;
}
$all_edges[] = array($ymin, $ymax, $xval, $invslope);
if ($ymin < $scanline) { $scanline = $ymin; }
} else {
if ($y1 < $scanline) { $scanline = $y1; }
if ($y2 < $scanline) { $scanline = $y2; }
}
}
// draw
$active = array();
do {
// add edges to active array
$tmp = array();
$n = count($all_edges);
for($i=0; $i<$n; $i++) {
if ($all_edges[$i][0] == $scanline) {
$active[] = $all_edges[$i];
} else {
$tmp[] = $all_edges[$i];
}
}
$all_edges = $tmp;
// remove previous edges from active array
$tmp = array();
$n = count($active);
for($i=0; $i<$n; $i++) {
if ($active[$i][1] > $scanline) {
$tmp[] = $active[$i];
}
}
$active = $tmp;
// sort active tab
$n = count($active);
for($i=0; $i<$n-1; $i++) {
$min = $i;
for($k=$i+1; $k<$n; $k++) {
if ($active[$k][2] < $active[$min][2]) { $min = $k; }
}
if ($i != $min) {
$tmp = $active[$i];
$active[$i] = $active[$min];
$active[$min] = $tmp;
}
}
// draw
$n = count($active);
for($i=0; $i<$n; $i+=2) {
if ($i+1 < $n) {
if ($tmp[$i][2] == $active[$i+1][2]) {
imagesetpixel($img, round($active[$i][2]), $scanline, $color);
} else {
imageline($img, round($active[$i][2]), $scanline, round($active[$i+1][2]), $scanline, $color);
}
}
}
// increment x values
$n = count($active);
for($i=0; $i<$n; $i++) { $active[$i][2] += $active[$i][3]; }
$scanline++;
} while (count($all_edges) + count($active) > 0);
}
?>

tatlar
<?php function _makeFiveSidedStar( $x, $y, $radius, $shape='polygon', $spiky=NULL ) {
   // $x, $y co-ords of origin (in pixels), $radius (in pixels), $shape - 'polygon' or 'star', $spikiness - ratio between 0 and 1
   $point = array() ;                                                                                                                    
   $angle = 360 / 5 ;                                                                                                                    
   $point[0]['x'] = $x ;                                                                                                                
   $point[0]['y'] = $y - $radius ;                                                                                                      
   $point[2]['x'] = $x + ( $radius * cos( deg2rad( 90 - $angle ) ) ) ;
   $point[2]['y'] = $y - ( $radius * sin( deg2rad( 90 - $angle ) ) ) ;
   $point[4]['x'] = $x + ( $radius * sin( deg2rad( 180 - ( $angle*2 ) ) ) ) ;
   $point[4]['y'] = $y + ( $radius * cos( deg2rad( 180 - ( $angle*2 ) ) ) ) ;
   $point[6]['x'] = $x - ( $radius * sin( deg2rad( 180 - ( $angle*2 ) ) ) ) ;                                                            
   $point[6]['y'] = $y + ( $radius * cos( deg2rad( 180 - ( $angle*2 ) ) ) ) ;
   $point[8]['x'] = $x - ( $radius * cos( deg2rad( 90 - $angle ) ) ) ;                                                                  
   $point[8]['y'] = $y - ( $radius * sin( deg2rad( 90 - $angle ) ) ) ;
   if( $shape == 'star' ) {
       if( $spiky == NULL ) $spiky = 0.5 ;  // default to 0.5
       $indent = $radius * $spiky ;
       $point[1]['x'] = $x + ( $indent * cos( deg2rad( 90 - $angle/2 ) ) ) ;                                                            
       $point[1]['y'] = $y - ( $indent * sin( deg2rad( 90 - $angle/2 ) ) ) ;                                                    
       $point[3]['x'] = $x + ( $indent * sin( deg2rad( 180 - $angle ) ) ) ;                                                              
       $point[3]['y'] = $y - ( $indent * cos( deg2rad( 180 - $angle ) ) ) ;
       $point[5]['x'] = $x ;                                                                                                            
       $point[5]['y'] = $y + ( $indent * sin( deg2rad( 180 - $angle ) ) ) ;
       $point[7]['x'] = $x - ( $indent * sin( deg2rad( 180 - $angle ) ) ) ;                                                              
       $point[7]['y'] = $y - ( $indent * cos( deg2rad( 180 - $angle ) ) ) ;                                                              
       $point[9]['x'] = $x - ( $indent * cos( deg2rad( 90 - $angle/2 ) ) ) ;                                                            
       $point[9]['y'] = $y - ( $indent * sin( deg2rad( 90 - $angle/2 ) ) ) ;
   }
   ksort( $point ) ;
   $coords = array() ;  // new array                                                                                                                
   foreach( $point as $pKey=>$pVal ) {                                                                                                  
       if( is_array( $pVal ) ) {                                                                                                        
           foreach( $pVal as $pSubKey=>$pSubVal ) {                                                                                      
               if( !empty( $pSubVal ) ) array_push( $coords, $pSubVal ) ;                                                                
           }                                                                                                                            
       }                                                                                                                                
   }
   return $coords ;
}
$values = _makeFiveSidedStar( 100, 100, 50, 'star' ) ;
// Put values into imagepolygon function. You need to define the $image and $color, and flush it out to an image type.?>

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