如何使用 bindless 指定 UBO 绑定？

Posted 2023-02-22

【中文标题】如何使用 bindless 指定 UBO 绑定？

【英文标题】：How to specify UBO binding with bindless?

【发布时间】：2016-11-01 00:43:04

【问题描述】：

我用 vec4 colorA's 和 colorB's 像这样创建了 2+ 个简单的 UBO。使用 std140 的不必要复杂的 UBO 创建/绑定过程，我只会得到黑屏。如何在使用 glCreate 时指定哪个索引并让这个混乱工作，以便我可以选择 colorA 或 colorB？

//APP
glCreateBuffers(1, &testUBO);
glNamedBufferData(testUBO, sizeof(glm::vec4), 0, GL_DYNAMIC_DRAW);
glGetNamedBufferParameterui64vNV(testUBO, GL_BUFFER_GPU_ADDRESS_NV, &uboScene_64);
glMakeNamedBufferResidentNV(testUBO, GL_READ_ONLY);


glm::vec4 myVec4 = glm::vec4(0.f, 1.f, 0.f, 1.f); //add to structs.h
glNamedBufferSubData(testUBO, 0, sizeof(glm::vec4), &myVec4

//SHARED HEADER
typedef glm::vec4 vec4;

layout(std140, binding = 0) uniform sceneBuffer

    vec4 colorA;
;

layout(std140, binding = 1) uniform objectBuffer

    vec4 colorB;
;

//SHADER PROGRAM
void main()

    Ci = colorA;
    Ci = colorB;

【参考方案1】：

鉴于此着色器：

//GLSL
layout(std140, binding = 0) uniform sceneBuffer

    vec4 colorA;
;

layout(std140, binding = 1) uniform objectBuffer

    vec4 colorB;
;

还有这个 C++ 缓冲区初始化代码：

//Create scene buffer.
glCreateBuffers(1, &sceneUbo);
glNamedBufferStorage(sceneUbo, sizeof(glm::vec4), 0, GL_DYNAMIC_STORAGE_BIT);

glm::vec4 myVec4 = glm::vec4(0.f, 1.f, 0.f, 1.f);
glNamedBufferSubData(sceneUbo, 0, sizeof(glm::vec4), &myVec4);

//Create object buffer
glCreateBuffers(1, &objectUbo);
glNamedBufferStorage(objectUbo, sizeof(glm::vec4), 0, GL_DYNAMIC_STORAGE_BIT);

glm::vec4 myVec4 = glm::vec4(0.f, 1.f, 0.f, 1.f);
glNamedBufferSubData(objectUbo, 0, sizeof(glm::vec4), &myVec4);

NV_uniform_buffer_unified_memory“bindless”代码如下所示：

//Get addresses
GLuint64 sceneUboAddr;
glGetNamedBufferParameterui64vNV(sceneUbo, GL_BUFFER_GPU_ADDRESS_NV, &sceneUboAddr);
glMakeNamedBufferResidentNV(sceneUbo, GL_READ_ONLY);

GLuint64 objectUboAddr;
glGetNamedBufferParameterui64vNV(objectUbo, GL_BUFFER_GPU_ADDRESS_NV, &objectUboAddr);
glMakeNamedBufferResidentNV(objectUbo, GL_READ_ONLY);

//You have to call this to turn on bindless buffers.
glEnableClientState(UNIFORM_BUFFER_UNIFIED_NV);

//0 represents the scene UBO's `binding` from GLSL:
glBufferAddressRangeNV(UNIFORM_BUFFER_ADDRESS_NV, 0, sceneUboAddr, sizeof(glm::vec4));
//1 represents the object UBO's `binding` from GLSL:
glBufferAddressRangeNV(UNIFORM_BUFFER_ADDRESS_NV, 1, objectUboAddr, sizeof(glm::vec4));

请注意，此扩展实际上需要glEnable/DisableClientState，这是一个从核心配置文件中删除的函数。所以你需要使用兼容性配置文件来使用它。

为了证明非绑定代码几乎不是“不必要的复杂”，这里是：

//The first 0 represents the scene UBO's `binding` from GLSL:
glBindBufferRange(GL_UNIFORM_BUFFER, 0, sceneUbo, 0, sizeof(glm::vec4));
//1 represents the object UBO's `binding` from GLSL:
glBindBufferRange(GL_UNIFORM_BUFFER, 1, objectUbo, 0, sizeof(glm::vec4));

【讨论】：

谢谢，错过了对glBufferAddressRangeNV的调用