imagepng
Function to draw a n-sided regular polygon
<?php
$img = imagecreatetruecolor(1360,768);
function regularPolygon($img,$x,$y,$radius,$sides,$color)
{
$points = array();
for($a = 0;$a <= 360; $a += 360/$sides)
{
$points[] = $x + $radius * cos(deg2rad($a));
$points[] = $y + $radius * sin(deg2rad($a));
}
return imagepolygon($img,$points,$sides,$color);
}
regularPolygon($img,1360/2,768/2,300,8,0xffffff);//Test draw
header('Content-type: image/png');
imagepng($img);
imagedestroy($img);
?>
imagepolygon
(PHP 4, PHP 5)
imagepolygon — Draws a polygon
Description
bool imagepolygon
( resource
$image
, array $points
, int $num_points
, int $color
)
imagepolygon() creates a polygon in the given
image.
Parameters
-
image -
An image resource, returned by one of the image creation functions, such as imagecreatetruecolor().
-
points -
An array containing the polygon's vertices, e.g.:
points[0] = x0 points[1] = y0 points[2] = x1 points[3] = y1 -
num_points -
Total number of points (vertices).
-
color -
A color identifier created with imagecolorallocate().
Return Values
Returns TRUE on success or FALSE on failure.
Examples
Example #1 imagepolygon() example
<?php
// Create a blank image
$image = imagecreatetruecolor(400, 300);
// Allocate 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,
$col_poly);
// Output the picture to the browser
header('Content-type: image/png');
imagepng($image);
imagedestroy($image);
?>
The above example will output something similar to:
See Also
- imagecreate() - Create a new palette based image
- imagecreatetruecolor() - Create a new true color image
add a note
User Contributed Notes
imagepolygon - [5 notes]
licson0729 at gmail dot com ¶
11 months ago
licson0729 at gmail dot com ¶
11 months ago
Here's a function to draw a n-sided star:
<?php
function drawStar($img,$x,$y,$radius,$sides,$color,$spikness=0.5)
{
$point =array();
$t = 0;
for($a = 0;$a <= 360;$a += 360/($sides*2))
{
$t++;
if($t % 2 == 0)
{
$point[] = $x + ($radius * $spikness) * cos(deg2rad($a));
$point[] = $y + ($radius * $spikness) * sin(deg2rad($a));
}else{
$point[] = $x + $radius * cos(deg2rad($a));
$point[] = $y + $radius * sin(deg2rad($a));
}
}
return imagepolygon($img,$point,$sides*2,$color);
}
?>
tatlar at yahoo dot com ¶
6 years ago
Function to get 5-sided polygon (pentagon) or star (pentagram) co-ords.
<?php
function _makeFiveSidedStar( $x, $y, $radius, $shape='polygon', $spiky=NULL ) {
$point = array() ; // new 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 ; // degree of spikiness, 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 ;
}
$values = _makeFiveSidedStar( 100, 100, 50, 'star' ) ;
?>
glowell at flash dot net ¶
7 years ago
Something to be aware of, ImagePolygon appears to convert the array of points passed to it from whatever format they may have been in originally into integers. This means if you pass it an array of floats (after running a rotation routine for example) the floats will be changed to integers INSIDE THE ORIGINAL ARRAY.
An extreme example: if for some reason you had an unit-sized polygon pt-array ( -1<x|y<1 for easy scaling purpose for instance) and for some reason your code calls imagepolygon on it (why? it'd only be a dot anyway) the array would be unusable after that (all either 1s, 0s or -1s). Scaling a unit-sized array, drawing it and then scaling it again will also may have a different result than expected.
Obviously, if the array in its original state is important to your code, it should use a copy of the original array for this call. If your code draws the same polygon multiple times but resizes it for different cases, you should have each size be created off an original template rather than adjusting a single polygon array.
jsnell at networkninja dot com ¶
12 years ago
Here are some handy routines for rotation and translation of polygons. Scaling could be added easily as well.
<?php
function translate_point(&$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;
}
?>