Arrays 索引到第二个数组元素总是返回零

我有一个UBO，看起来像这样：

#version 450
#extension GL_ARB_separate_shader_objects : enable

const uint InstanceCount = 64;

layout(std140, align = 16, binding = 0) uniform UBO
{
    vec4 array_indices[InstanceCount];
    mat4 proj;
    mat4 model;
    mat4 models[InstanceCount];
    uint selection[128];
} ubo;

layout(location = 1) out uint is_selected;

void main() {
    uint id = gl_InstanceIndex;
    uint num_index = id / 32;
    uint bit_index = id % uint(32);
    uint n = ubo.selection[num_index];
    is_selected = n & (1u << bit_index);
...
}

const int num_selection_elements = 128;
const int num_selection_words = num_selection_elements / 4
layout(std140, align = 16, binding = 0) uniform UBO
{
    ...
    uvec4 selection[num_selection_words];
} ubo;

void main() {
    uint id = gl_InstanceIndex;
    uint bit_index = id % 32;
    uint word_index = (id / 32) % 4;
    uint vec_index = id / (num_selection_words * 32 * 4);
    uint n = ubo.selection[vec_index][word_index];
    is_selected = n & (1u << bit_index);
...
}

每个顶点着色器实例从

uint selection[128]

访问一位，如下所示：

#version 450
#extension GL_ARB_separate_shader_objects : enable

const uint InstanceCount = 64;

layout(std140, align = 16, binding = 0) uniform UBO
{
    vec4 array_indices[InstanceCount];
    mat4 proj;
    mat4 model;
    mat4 models[InstanceCount];
    uint selection[128];
} ubo;

layout(location = 1) out uint is_selected;

void main() {
    uint id = gl_InstanceIndex;
    uint num_index = id / 32;
    uint bit_index = id % uint(32);
    uint n = ubo.selection[num_index];
    is_selected = n & (1u << bit_index);
...
}

const int num_selection_elements = 128;
const int num_selection_words = num_selection_elements / 4
layout(std140, align = 16, binding = 0) uniform UBO
{
    ...
    uvec4 selection[num_selection_words];
} ubo;

void main() {
    uint id = gl_InstanceIndex;
    uint bit_index = id % 32;
    uint word_index = (id / 32) % 4;
    uint vec_index = id / (num_selection_words * 32 * 4);
    uint n = ubo.selection[vec_index][word_index];
    is_selected = n & (1u << bit_index);
...
}

---

vkm:：mat4

是一个具有单个成员浮点arr[16]的类。

在

std140

布局中，所有数组都有一个元素到元素数组跨距，向上舍入到最接近的

sizeof（vec4）

，即16字节。因此，除非

u32

实际上是一个16字节的结构，

u32选择[128]与您的定义不匹配

您的GLSL需要做的是将
uvec4
数组设置为比其实际大小小4倍的数组，并按如下方式对数组进行索引：

#version 450
#extension GL_ARB_separate_shader_objects : enable

const uint InstanceCount = 64;

layout(std140, align = 16, binding = 0) uniform UBO
{
    vec4 array_indices[InstanceCount];
    mat4 proj;
    mat4 model;
    mat4 models[InstanceCount];
    uint selection[128];
} ubo;

layout(location = 1) out uint is_selected;

void main() {
    uint id = gl_InstanceIndex;
    uint num_index = id / 32;
    uint bit_index = id % uint(32);
    uint n = ubo.selection[num_index];
    is_selected = n & (1u << bit_index);
...
}

const int num_selection_elements = 128;
const int num_selection_words = num_selection_elements / 4
layout(std140, align = 16, binding = 0) uniform UBO
{
    ...
    uvec4 selection[num_selection_words];
} ubo;

void main() {
    uint id = gl_InstanceIndex;
    uint bit_index = id % 32;
    uint word_index = (id / 32) % 4;
    uint vec_index = id / (num_selection_words * 32 * 4);
    uint n = ubo.selection[vec_index][word_index];
    is_selected = n & (1u << bit_index);
...
}

const int num\u selection\u elements=128；
const int num_selection_words=num_selection_elements/4
布局（std140，对齐=16，绑定=0）统一UBO
{
...
uvec4选择[num_selection_words]；
}ubo；
void main（）{
uint id=gl_实例索引；
uint位索引=id%32；
uint单词索引=（id/32）%4；
uint向量索引=id/（选择字数*32*4）；
uint n=ubo.selection[vec_index][word_index]；
经过更多测试后，这是对
uvec4
数组的最终正确索引：

uint index = gl_InstanceIndex;
const uint vec_index = index / 128; // 128 = 32 * 4 = vec size
index %= 128;
uint num_index = index / 32;
const uint bit_index = index % 32;
const uint n = ubo.selection[vec_index][num_index];
is_selected = n & (1u << bit_index);

uint index=gl\u InstanceIndex；
const uint vec_index=index/128；//128=32*4=vec size
指数%=128；
uint num_index=index/32；
常量位索引=索引%32；
const uint n=ubo.selection[vec_index][num_index]；
是否选择了_=n&（1U）你如何将数据上传到着色器？那就是，你认为C或C++结构是什么？相当于GLSL定义？我附加了C++结构，一个填充问题是我唯一能想到的问题，但是我不知道如何修复/检测它。如果你有问题的答案，用答案加上答案写它。n、 不要将其编辑到您的问题中。谢谢，尽管我已经测试了它，而且选择现在根本不起作用，尽管RenderDoc现在说UBO占用的空间更少。我刚刚醒来，所以如果我有新想法，我会稍后与大家分享。这是一个小应用程序（仅适用于Linux），我应该把它发布到某个地方，以便人们可以尝试编译它吗？RenderDoc说选择数组不是空的，所以可能是数组中的索引..或其他一些错误原因。谢谢！你的答案是正确的，除了vec数组索引，我通过反复尝试最终找到并编辑了我的原始帖子。