imagefilledpolygon()

(PHP 4, PHP 5, PHP 7)

画一多边形并填充

说明

imagefilledpolygon()在$image图像中画一个填充了的多边形。

$points参数是一个按顺序包含有多边形各顶点的x和y坐标的数组。

$num_points参数是顶点的总数，必须大于 3。

imagefilledpolygon()例子

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

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);
}

My version of drawStar (with examples) 

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.

Actually the minimum it allows is 3. It says "Total number of vertices, which must be bigger than 3." but it allows 3...

There is a simple function to draw a filled point with a chosen radius and color. 

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. 

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. 

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