c++ - openCL:如何将 uint4 转换为 uchar4？

Question

我想将 uint4 vector 转换为 uchar4 vector ，但我不确定这样做的正确方法是什么:

const uint4 res;
res = read_imageui(input, sampler, pos_read);

output[p]   = res           // error: assigning to '__global uchar4' from incompatible type 'const uint4'; 

output[p]   = (uchar4)res;  // error: invalid conversion between ext-vector type 'uchar4' and 'uint4'

output[p].x = (uchar)res.x; // 
output[p].y = (uchar)res.y; //
output[p].z = (uchar)res.z; // works, but is this the only/right way to go?
output[p].w = (uchar)res.w; //

Answer 1

使用它进行简单的转换:

output[p] = convert_uchar4(res); //For a simple conversion

或其中之一用于手工转换:

output[p] = convert_uchar4<_sat><_roundingMode>(res); //For a precise conversion

在哪里，<_sat>是可选的，它定义了当值超出范围时是否饱和。和 <_roundingMode>也可选，可以是_rte (最近的偶数)，_rtp (朝向 inf)，_rtn (朝向-inf)或_rtz (接近零)

如有更多问题，请联系 OpenCL Reference Card Page 5 .或者 Conversion of types for OpenCL