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image_brick.html
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<html>
<!-- Creation date: 15/03/02 -->
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>image_brick</title>
<meta name="Description" content="">
<meta name="Keywords" content="">
<meta name="Author" content="Julian MacDonald">
<meta name="Generator" content="AceHTML 4 Pro">
</head>
<body BGCOLOR="#f8e89e">
<font face="tahoma" size="2">
<table><tr>
<td><img SRC="textures/pt_image_brick.jpg"></td>
<td><font face="tahoma" size="2">
The basis of this texture is an brick-like image consisting of red bricks (R=1,G=0,B=0) and green
mortar (R=0,G=1,B=0) as shown below:<br>
<img SRC="textures/brick_image.jpg"><br>
This image is selected with the image pattern module. Because of the way the colours have been used,
the green output of this module will have a value of 1 for all green parts of the image (the "bricks") and
0 for everything else, and the red output will be 1 for all the red parts (the "mortar") and 0
everywhere else. This enables the bricks and the mortar to have different properties. The red output
is multiplied by a noise function (Noise A below) fed into a 'mortar' colour map.<br>
<img SRC="textures/pt_brick_noise1.jpg"><br>
This has the result
of applying the function only to the mortar. The green output is similarly fed into a brick-like colour
map using the noise function (Noise B below). <br>
<img SRC="textures/pt_brick_noise2.jpg"><br>
</font></td>
</tr></table>
The two results are summed to give the bricks and the mortar diffuse colour.<br>
<br>
We want the bricks to stick out from the surface. This could be simulated using the bump height
property but for a more realistic effect, true displacement mapping is used. The green output of
the image module has been used to select only the bricks. This has been scaled down by 0.5 and combined
with another noise function (Noise C - below) to give an extra random bumpiness. A linear
transform (see below) has been applied to scale down this noise in order to add small-scale bumpiness
to the bricks.<br>
<img SRC="textures/pt_brick_noise3.jpg"><img SRC="textures/pt_brick_trans.jpg"><br>
A further scaling factor of 0.05 has been applied to the combination of brick and noise bumps to reduce the
displacement to a more realistic level.
<br>
<br>
<br>
<a href="textures.html#ex_textures"><b><font size="4">Back to Textures</font></b></a><br>
</font>
</body>
</html>