// vr.diderot
//
// volume rendering example in Diderot
//

input string dataFile;		// name of dataset
input real stepSz;		// size of steps
input vec<3> light;
input int wid = 640;
input int ht = 480;

image[3] img = load (dataFile);

field#1[3] F = convolve (bspln3, img);
 
actor RayCast (int row, int col)
{
    vec<3>	dir = (real(row), real(col), 0.0);
    vec<3>	pos = (0.0, 0.0, 0.0);
    real	t = 0.0;
    real[4]	color = (0.0, 0.0, 0.0, 0.0);	

    update
    {
	vec<3> pt = pos + t*dir;
	t = t + stepSz;
	vec<3> g = (D F)@pt;
	color = over(color, phong(light, g, txf(F@pt)));
	if (color[3] >= 0.999)
	    stabilize;
    }

}

initially
  [ RayCast(r, c) | r in 0 .. ht-1, c in 0 .. wid-1 ];

<script type="text/javascript">//<![CDATA[
		function toggle_ffErrors() {
			var errorsblock = document.getElementById("ffErrorsBlock");
			var errorsgroup = document.getElementById("ffErrors");
			if (errorsblock.style.display == "none") {
				errorsblock.style.display = "block";
				errorsgroup.style.right = "10px";
			} else {
				errorsblock.style.display = "none";
				errorsgroup.style.right = "300px";
			}
		}
//]]></script>
<div id="ffErrors">
<a href="javascript:toggle_ffErrors();">Click to toggle</a>
<div id="ffErrorsBlock">
	<div class="error">does not end with &lt;/html&gt; tag</div>
	<div class="error">does not end with &lt;/body&gt; tag</div>
	<div class="info">The output has ended thus: &gt;= 0.999)
	    stabilize;
    }

}

initially
  [ RayCast(r, c) | r in 0 .. ht-1, c in 0 .. wid-1 ];</div>
</div></div>
</body></html>