How to draw a simple 6-sided star img where x,y is center of the star and s is the size:
function drawStar($img, $x, $y, $s, $color) {
$x=$x-$s/2;
$y=$y-$s/4;
$points=array($x,$y, $x+$s/2,$y+$s, $x+$s,$y);
imagefilledpolygon($img, $points, 3, $color);
$points=array($x,2/3*$s+$y, $x+$s/2,$y-$s/3, $x+$s,2/3*$s+$y);
imagefilledpolygon($img, $points, 3, $color);
}imagefilledpolygon
(PHP 4, PHP 5, PHP 7, PHP 8)
imagefilledpolygon — Dibujar un polígono con relleno
Descripción
imagefilledpolygon() crea un polígono relleno
en image.
Parámetros
imageUn recurso image, es devuelto por una de las funciones de creación de imágenes, como imagecreatetruecolor().
points-
Una matriz que contiene las coordenadas
xeyde los vértices del polígono consecutivamente. num_points-
Número total de vértices, lo que debe ser al menos 3.
color-
Un identificador de color creado con imagecolorallocate().
Ejemplos
Ejemplo #1 Ejemplo de imagefilledpolygon()
<?php
// establecer una matriz de puntos para el polígono
$valores = 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)
);
// crear imagen
$imagen = imagecreatetruecolor(250, 250);
// asignar colores
$fondo = imagecolorallocate($imagen, 0, 0, 0);
$azul = imagecolorallocate($imagen, 0, 0, 255);
// rellenar el fondo
imagefilledrectangle($imagen, 0, 0, 249, 249, $fondo);
// dibujar un polígono
imagefilledpolygon($imagen, $valores, 6, $azul);
// volcar imagen
header('Content-type: image/png');
imagepng($imagen);
imagedestroy($imagen);
?>El resultado del ejemplo sería algo similar a:
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User Contributed Notes 9 notes
martin at eksperimentrum dot dk ¶
6 years ago
Steween ¶
7 years ago
My version of drawStar (with examples)
<?php
header ("Content-type: image/png");
/* drawStar or regular polygon
$x, $y -> Position in the image
$radius -> Radius of the star
$spikes -> Number of spikes (min 2)
$ratio -> Ratio between outer and inner points
$dir -> Rotation 270° for having an up spike( with ratio<1)
*/
function drawStar($x, $y, $radius, $spikes=5, $ratio=0.5, $dir=270) {
$coordinates = array();
$angle = 360 / $spikes ;
for($i=0; $i<$spikes; $i++){
$coordinates[] = $x + ( $radius * cos(deg2rad($dir+$angle*$i)));
$coordinates[] = $y + ( $radius * sin(deg2rad($dir+$angle*$i)));
$coordinates[] = $x + ($ratio*$radius * cos(deg2rad($dir+$angle*$i + $angle/2)));
$coordinates[] = $y + ($ratio*$radius * sin(deg2rad($dir+$angle*$i + $angle/2)));
}
return $coordinates ;
}
// 14*20+24*2 = 328 Examples
$im = imagecreate(800,600);
imagecolorallocate($im, 0, 0, 0);
$w = imagecolorallocate($im, 255, 255, 255);
$r = imagecolorallocate($im, 255, 0, 0);
for ($spikes=2; $spikes<16; $spikes++) { //[2-15]
for ($ratio=1; $ratio<21; $ratio++) { //[0.1-2.0]
$values = drawStar(40*$ratio-20, $spikes*40-60, 10, $spikes, $ratio/10);
imagefilledpolygon($im, $values, count($values)/2, ($ratio % 5 == 0) ? $r : $w);
}
}
for ($dir=0; $dir<24; $dir++) {
$values = drawStar(30*$dir+20, 580, 10, 2, 1.5, $dir*15);
imagefilledpolygon($im, $values, count($values)/2, $w);
$values = drawStar(30*$dir+20, 580, 10, 2, 0.2, $dir*15);
imagefilledpolygon($im, $values, count($values)/2, $r);
}
imagepng($im);
imagedestroy($im);
?>
rbenheidorn at gmail dot com ¶
9 years ago
Discovered while working on printing geographical boundaries to an image: if you provide floating point vertices, then the decimal value is automatically truncated. This can cause images drawn with floating point vertices to shift slightly towards the top-left corner. My personal resolution is to round all of the vertices to their nearest whole values, which eliminates this shift.
austinoblouk at yahoo dot com ¶
15 years ago
Actually the minimum it allows is 3. It says "Total number of vertices, which must be bigger than 3." but it allows 3...
webmaster at mywebsolution dot de ¶
17 years ago
Just thought that 'tatlar at yahoo dot com's function has some redundant code in it, so I tried to "improve" it. Now you can choose a variable number of spikes.
<?php
error_reporting(E_ALL);
function drawStar($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($im);
?>
jylyn at hotmail dot com ¶
18 years ago
In spite of what it says about requiring more than 3 vertices, it is possible to draw a triangle with this function!
etnekor at tar dot hu ¶
18 years ago
There is a simple function to draw a filled point with a chosen radius and color.
<?php
function drawPoint($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);
}
?>
tatlar at yahoo dot com ¶
18 years ago
<?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.?>
Arnapou ¶
17 years ago
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);
}
?>