纹理映射中的双线性插值

 A texture mapping technique that produces a reasonably realistic image, also known as "bilinear filtering" and "bilinear texture mapping." An algorithm is used to map a screen pixel location to a corresponding point on the texture map. A weighted average of the attributes (color, alpha, etc.) of the four surrounding texels is computed and applied to the screen pixel. This process is repeated for each pixel forming the object being textured.

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双线性插值是一种产生真实感图像的纹理映射技术，通常也被称为"双线性滤波"或者"双线性纹理映射"。该算法被用于将屏幕象素的位置映射到纹理贴图上相应的点。加权平均计算出相邻的四个纹理单元(纹理贴图上的每一个象素点)的属性(颜色，混合因子等)，然后将计算出的结果应用到屏幕象素上，重复这个过程直到组成物体的所有象素都被映射完为止。

 

The term bilinear refers to the performing of interpolations in two dimensions (horizontal and vertical). The top and bottom pairs of each texel quadrant are averaged (horizontal) and then their results are averaged (vertical). This method is often used in conjunction with MIP mapping

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双线性一词就是指在二维(水平和垂直)上进行插值。处于上象限的两个象素，和下象限的两个象素先水平方向组内求均值，然后再竖直方向上将两个均值求平均。这种方法经常和Mip Maping技术联合使用。

 

 

需要强调的是：通常的纹理都包含有红色，绿色，蓝色三原色通道，以及alpha透明通道，所以在每次混合的时候，应该分别对R，G，B，A四个因子进行单独地计算。

PS：双线性插值就是为了缩放纹理，和缩放图像是一个道理，纹理和图像在内存里面是等价的。