解决Z-fighting, 使用Polygon Offset

[ 2007-02-27 18:02:51 | 作者: Admin ]

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当两个面共面时,会出现十分难看的z - fighting 问题,

要解决此问题可以使用, Polygon Offset, 方法如下:

drawSomething();

//同一位置绘制另一个东西
glEnable( GL_POLYGON_OFFSET_FILL ); // This is the one we need...
glPolygonOffset( g_OffsetFactor, g_OffsetUnit );

drawOtherthing();

glPolygonOffset( 0.0f, 0.0f );
glDisable( GL_POLYGON_OFFSET_FILL );

其中
g_OffsetFactor代表 factor,
g_OffsetUnit 代表 units,

关于factor, units 的解释如下:

When GL_POLYGON_OFFSET is enabled, each fragment's depth
value will be offset after it is interpolated from the depth
values of the appropriate vertices. The value of the offset
is factor * DZ + r * units, where DZ is a measurement of
the change in depth relative to the screen area of the
polygon, and r is the smallest value that is guaranteed to
produce a resolvable offset for a given implementation. The
offset is added before the depth test is performed and
before the value is written into the depth buffer.
glPolygonOffset is useful for rendering hidden-line images,
for applying decals to surfaces, and for rendering solids
with highlighted edges.

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