mirror of
https://github.com/dhewm/iddevnet.git
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112 lines
4.4 KiB
HTML
112 lines
4.4 KiB
HTML
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN">
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<!-- saved from url=(0043)https://www.iddevnet.com/doom3/lighting.php -->
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<html><head><meta http-equiv="Content-Type" content="text/html; charset=windows-1252">
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<title>id.sdk [Lighting]</title>
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<link rel="stylesheet" href="style.css">
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</head>
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<body marginwidth="0" marginheight="0" topmargin="0" leftmargin="0">
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<table border=0 cellpadding=0 cellspacing=0 style="width: 100%; height: 99px">
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<tr>
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<td style="width: 171px"><img src="images/doom.jpg" style="width: 171px; height: 99px" alt=""></td>
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<td style="background: url(images/tile.gif)">
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<table border=0 cellpadding=0 cellspacing=0 width=600>
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<tr>
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<td style="height: 19px; background: url(images/sdk.gif) no-repeat"></td>
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<td rowspan=4 align=right><img src="images/id.gif" style="width: 42px; height: 99px" alt=""></td>
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</tr>
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<tr><td style="height: 29px; background: url(images/top.jpg) no-repeat"></td></tr>
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<tr><td style="height: 27px; background: url(images/middle.gif)" class="title"> Making DOOM 3 Mods : Lighting</td></tr>
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<tr><td style="height: 24px; background: url(images/bottom.jpg) no-repeat"></td></tr>
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</table>
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</td>
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</tr>
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</table>
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<table border=0 cellpadding=0 cellspacing=0 style="width: 770px">
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<tr>
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<td colspan=2 style="background: url(images/boxtop.gif);"><img src="images/span.jpg" style="width: 397px; height: 20px; float: left" alt=""></td>
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</tr>
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<tr>
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<td style="vertical-align: top; width: 152px; background: url(images/tileleft.gif)">
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<div class="leftMenu">
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<script src="menu.js"></script>
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</div>
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</td>
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<td class="mainContent">
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<p>
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The biggest technological advancement in the Doom 3 engine is the
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unified per-pixel lighting.
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</p><p>
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In previous engines, world geometry
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went through a different rendering and lighting path than model
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geometry (such as characters and objects). If an object moved,
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the lighting would always look wrong on it. Either the lighting
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would not move with the object, or there simply wouldn't be
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lighting and shadows for the object. It is very hard to create
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tension because you would get the effect seen in cartoons
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where you could pick out the brick that was going to move because
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it was always a different color.
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</p><p>
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In Doom 3, however, all triangles go through the same render backend.
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This means you can have an entity next to a piece of world geometry,
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and they will look exactly the same. You never know which panel
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the imp is going to pop out of, because all the wall panels integrate
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seemlessly into the world.
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</p><p>
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Every object has a material on it. This material defines how the lighting
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and shadow system will interact with the object (it also defines how the
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sound system interacts, but we won't get in to that).
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</p><p>
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Each triangle has three seperate images associated with it: the bump map,
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the diffuse map, and the specular map.
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</p><p>
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The bump map (or normal map) is a way to simulate geometry on a flat surface.
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Normally, when light hits a flat surface, it reflects at the exact angle
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of impact. When a surface has a normal map on it, the angle of reflection
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is perturbed some amount depending on the RGB value of the pixel the light
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hit.
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</p><p>
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<img src="images/lighting_a.gif">
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</p><p>
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Bump maps are explained in greater detail in the <a href="bumpmaps.html">bumpmaps</a>
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section.
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</p><p>
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A specular map is a gray scale image that defines how 'shiny' an object is. The
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more white a pixel is, the more it reflects light back in to the camera. Something
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like a dirt road would pretty much have a pure black specular map, but something
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like chrome would have almost a pure white specular map.
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</p><p>
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The diffuse map is what actually gives the object color. It should only be "local
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color" with no shadows or highlights because those will be added in later by the
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lighting system. The diffuse map should be created as if the object were being
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lit on all sides by pure white ambient light.
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<br>
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</p></td>
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</tr>
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<tr>
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<td colspan="2" bgcolor="#CCCCCC"><img src="images/span2.gif" style="width: 397px; height: 8px; float: left;"></td>
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</tr>
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</tbody></table>
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<table border="0" cellpadding="0" cellspacing="0" width="770">
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<tbody><tr>
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<td align="left" class="legalese">Copyright <20> 2004 <a href="http://www.idsoftware.com/">id software</a></td>
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</tr>
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</tbody></table>
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</body></html>
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