<?php
require_once("/usr/local/lib/php/20100525/phpchartdir.php");

# The x and y coordinates of the grid
$dataX = array(-10, -9, -8, -7, -6, -5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
    10);
$dataY = array(-10, -9, -8, -7, -6, -5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
    10);

# The values at the grid points. In this example, we will compute the values using
# the formula z = x * sin(y) + y * sin(x).
$dataZ = array_pad(array(), count($dataX) * count($dataY), 0);
for($yIndex = 0; $yIndex < count($dataY); ++$yIndex) {
    $y = $dataY[$yIndex];
    for($xIndex = 0; $xIndex < count($dataX); ++$xIndex) {
        $x = $dataX[$xIndex];
        $dataZ[$yIndex * count($dataX) + $xIndex] = $x * sin($y) + $y * sin($x);
    }
}

# Create a SurfaceChart object of size 720 x 600 pixels
$c = new SurfaceChart(720, 600);

# Add a title to the chart using 20 points Times New Roman Italic font
$c->addTitle("Surface Energy Density   ", "timesi.ttf", 20);

# Set the center of the plot region at (350, 280), and set width x depth x height to
# 360 x 360 x 270 pixels
$c->setPlotRegion(350, 280, 360, 360, 270);

# Set the data to use to plot the chart
$c->setData($dataX, $dataY, $dataZ);

# Spline interpolate data to a 80 x 80 grid for a smooth surface
$c->setInterpolation(80, 80);

# Add a color axis (the legend) in which the left center is anchored at (645, 270).
# Set the length to 200 pixels and the labels on the right side.
$c->setColorAxis(645, 270, Left, 200, Right);

# Set the x, y and z axis titles using 10 points Arial Bold font
$c->xAxis->setTitle("X (nm)", "arialbd.ttf", 10);
$c->yAxis->setTitle("Y (nm)", "arialbd.ttf", 10);
$c->zAxis->setTitle("Energy Density (J/m<*font,super*>2<*/font*>)", "arialbd.ttf", 10
    );

# Output the chart
header("Content-type: image/jpeg");
print($c->makeChart2(JPG));
?>
