GLSL中高效的双三次过滤代码?

问题描述

我想知道是否有人拥有完整，可运行且有效的代码来在glsl中进行双三次纹理过滤.有这个:

I'm wondering if anyone has complete, working, and efficient code to do bicubic texture filtering in glsl. There is this:

http://www .codeproject.com/Articles/236394/Bi-Cubic-and-Bi-Linear-Interpolation-with-GLSL 或者 https://github.com. com/visionworkbench/visionworkbench/blob/master/src/vw/GPU/Shaders/Interp/interpolation-bicubic.glsl

但是两者都执行16次纹理读取，而其中只有4次是必需的:

but both do 16 texture reads where only 4 are necessary:

https://groups.google.com/forum/#!topic/comp.graphics.api.opengl/kqrujgJfTxo

但是，上述方法使用了一个我不知道该怎么做的缺失的"cubic()"函数，并且还使用了一个无法解释的"texscale"参数.

However the method above uses a missing "cubic()" function that I don't know what it is supposed to do, and also takes an unexplained "texscale" parameter.

还有NVidia版本:

There is also the NVidia version:

https://developer.nvidia.com/gpugems/gpugems2/part-iii-high-quality-rendering/chapter-20-fast-third-order-texture-filtering

但是我相信这使用的是CUDA，它专用于NVidia的显卡.我需要glsl.

but I believe this uses CUDA, which is specific to NVidia's cards. I need glsl.

我可能可以将nvidia版本移植到glsl，但是我想先问一下是否有人已经拥有完整的，可以正常工作的glsl双三次着色器.

I could probably port the nvidia version to glsl, but thought I'd ask first to see if anyone already has a complete, working glsl bicubic shader.

推荐答案

我决定花一点时间来挖掘我以前的Perforce活动，并发现缺少的cube()函数；请享用！ :)

I decided to take a minute to dig my old Perforce activities and found the missing cubic() function; enjoy! :)

vec4 cubic(float v)
{
    vec4 n = vec4(1.0, 2.0, 3.0, 4.0) - v;
    vec4 s = n * n * n;
    float x = s.x;
    float y = s.y - 4.0 * s.x;
    float z = s.z - 4.0 * s.y + 6.0 * s.x;
    float w = 6.0 - x - y - z;
    return vec4(x, y, z, w);
}

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