HLSL:未对齐/打包浮动的索引 [英] HLSL: Index to unaligned/packed floats

问题描述

我有一个顶点着色器(2.0)做一些实例化-每个顶点都指定一个数组索引.

I have a vertex shader (2.0) doing some instancing - each vertex specifies an index into an array.

如果我有一个像这样的数组:

If I have an array like this:

float instanceData[100];

编译器为其分配100个常量寄存器.每个常量寄存器都是一个float4，因此它分配的空间是所需的4倍.

The compiler allocates it 100 constant registers. Each constant register is a float4, so it's allocating 4 times as much space as is needed.

我需要一种方法，使其仅分配25个常量寄存器，并在每个常量寄存器中存储四个值.

I need a way to make it allocate just 25 constant registers and store four values in each of them.

理想情况下，我想要一种在CPU和GPU上仍看起来像float[]的方法(现在我正在调用EffectParamter.SetValue(Single[])，我正在使用XNA).但是也可以手动打包和解包float4[].

Ideally I'd like a method where it still looks like a float[] on both the CPU and GPU (Right now I am calling EffectParamter.SetValue(Single[]), I'm using XNA). But manually packing and unpacking a float4[] is an option, too.

此外:这样做对性能有何影响?真的值得吗? (对我来说，这将每四到五次节省大约一批次).

Also: what are the performance implications for doing this? Is it actually worth it? (For me, this will save about one batch in every four or five).

推荐答案

这有帮助吗?:

float4 packedInstanceData[25];
...
float data = packedInstanceData[index / 4][index % 4];

这篇关于HLSL:未对齐/打包浮动的索引的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！