function render_polygons ($polygons, $vertex_color, $face_color, $wireframe, $dashes, $image_size, $scale
{
foreach ($polygons as $polygon) {
if (!is_array$polygon)) {
throw new Exception'Each polygon must be a list.');
} else if ((count$polygon)%3)!=0) {
throw new Exception'Each polygon must be a list like x1, y1, z1, x2, y2, z2, etc. The number of points therefore must be divisible by three.');
}
}
if (is_array$vertex_color)) {
if (count$vertex_color) != count$polygons)) {
throw new Exception'If vertex colors is an array, it must contain the same number of colors as the number of polygons.');
}
}
if (is_array$face_color)) {
if (count$face_color) != count$polygons)) {
throw new Exception'If face colors is an array, it must contain the same number of colors as the number of polygons.');
}
}
// if scale=0 then we auto-scale
if ($scale==0) {
$max = 0;
for ($i=0; $icount$polygons); $i++) {
for ($j=0; $jcount$polygons$i]); $j$j+3) {
if (abs$polygons$i][$j])>$max
$max = abs$polygons$i][$j]);
if (abs$polygons$i][$j+1])>$max
$max = abs$polygons$i][$j+1]);
}
}
if ($max>0)
$scale = ($image_size-2)/($max*2);
}
// the polygon arrays (x,y,z) must be converted into shapes (x,y)
$shapes = array();
$z_max = array();
for ($i=0; $icount$polygons); $i++) {
$max = $polygons$i][2];
for ($j=0; $jcount$polygons$i]); $j$j+3) {
$x = $polygons$i][$j];
$y = $polygons$i][$j+1];
// map each x,y coord to a screen position
$x = round$image_size/2 + $x$scale);
$y = round$image_size/2 - $y$scale);
$shapes$i][$j] = $x
$shapes$i][$j+1] = $y
// keep track of the maximum z-value for each shape
if ($polygons$i][$j+2]>$max
$max = $polygons$i][$j+2];
}
$shapes$i] = array_values$shapes$i]);
$z_max$i] = $max
}
// create a blank image
$image = image_create_alpha$image_size, $image_size);
// create the colors
if (!is_array$vertex_color))
$vertex_color = array_fill(0, count$polygons), $vertex_color);
if (!is_array$face_color))
$face_color = array_fill(0, count$polygons), $face_color);
// painter's algorithm - draw farther polygons first
array_multisort$z_max, SORT_DESC, $shapes, $face_color, $vertex_color);
// draw the polygons
for ($i=0; $icount$shapes); $i++) {
$v_color = allocate_color$image, $vertex_color$i]);
$f_color = allocate_color$image, $face_color$i]);
if (!$wireframe) {
imagefilledpolygon$image, $shapes$i], count$shapes$i])/2, $f_color);
}
imagepolygon$image, $shapes$i], count$shapes$i])/2, $v_color);
}
// draw dashes - BUGGY
if ($dashes) {
for ($i=0; $icount$shapes); $i++) {
$v_color = allocate_color$image, $vertex_color$i]);
$style = array$v_color, IMG_COLOR_TRANSPARENT, IMG_COLOR_TRANSPARENT, IMG_COLOR_TRANSPARENT, IMG_COLOR_TRANSPARENT);
imagesetstyle$image, $style);
imagepolygon$image, $shapes$i], count$shapes$i])/2, IMG_COLOR_STYLED);
}
}
return $image
}
eXorithm – Execute Algorithm: View / Run Algorithm render_polygons
