c++ - 一个粒子过多:生成了GL_INVALID_VALUE错误。 不满足着色器存储缓冲区的最低对齐要求

Question

我在粒子系统中遇到一个奇怪的错误。我可以动态设置缓冲区的大小，并且可以根据需要更改粒子的数量。我正在玩30k，40k之类的数字，介于两者之间。 40800达到了最大值……然后我从输出终端的标题中得到了错误。

这是代码:

Log::logInfo(m_Name, "Bind particle buffers...");

    /// ssbo sizes
    constexpr ptrdiff_t positionSSBOsize = sizeof(glm::vec4) * NUM_PARTICLES;
    constexpr ptrdiff_t velocitySSBOsize = sizeof(glm::vec2) * NUM_PARTICLES;
    constexpr ptrdiff_t forceSSBOsize = sizeof(glm::vec2) * NUM_PARTICLES;
    constexpr ptrdiff_t densitySSBOsize = sizeof(float) * NUM_PARTICLES;
    constexpr ptrdiff_t pressureSSBOsize = sizeof(float) * NUM_PARTICLES;

    /// total size
    constexpr ptrdiff_t packedBufferSize = positionSSBOsize + velocitySSBOsize + forceSSBOsize + densitySSBOsize + pressureSSBOsize;

    /// ssbo offsets
    constexpr ptrdiff_t positionSSBOoffset = 0;
    constexpr ptrdiff_t velocitySSBOoffset = positionSSBOsize;
    constexpr ptrdiff_t forceSSBOoffset = velocitySSBOoffset + velocitySSBOsize;
    constexpr ptrdiff_t densitySSBOoffset = forceSSBOoffset + forceSSBOsize;
    constexpr ptrdiff_t pressureSSBOoffset = densitySSBOoffset + densitySSBOsize;

    /// set inital positions
    this->initParticleSeeds(packedBufferSize, positionSSBOsize, m_PackedParticlesBufferHandle);

    /// bind to inital positions data
    this->bindBufferToVertexArrayObject(m_ParticlePositionVaoHandle, m_PackedParticlesBufferHandle, PARTICLE_SEEDS_NR);

    /// bindings 
    //@TODO: Here we got a problem after increasing NUM_PARTICLES, the error that the MAX_SHADER_STORAGE_BUFFER_BINDINGS are reached, thats why INVALID_ERROR is thrown
    Log::logInfo(m_Name, "Bind particle buffers: positions");
    glBindBufferRange(GL_SHADER_STORAGE_BUFFER, SHADER_PART_POS_NR, m_PackedParticlesBufferHandle, positionSSBOoffset, positionSSBOsize);   /// Particle Positions
    Log::logInfo(m_Name, "Bind particle buffers: velocities");
    glBindBufferRange(GL_SHADER_STORAGE_BUFFER, SHADER_PART_VEL_NR, m_PackedParticlesBufferHandle, velocitySSBOoffset, velocitySSBOsize);   /// Particle Velocities
    Log::logInfo(m_Name, "Bind particle buffers: force");
    glBindBufferRange(GL_SHADER_STORAGE_BUFFER, SHADER_PART_FRC_NR, m_PackedParticlesBufferHandle, forceSSBOoffset, forceSSBOsize);         /// Particle Force
    Log::logInfo(m_Name, "Bind particle buffers: density");
    glBindBufferRange(GL_SHADER_STORAGE_BUFFER, SHADER_PART_DNS_NR, m_PackedParticlesBufferHandle, densitySSBOoffset, densitySSBOsize);     /// Particle Density
    Log::logInfo(m_Name, "Bind particle buffers: pressure");
    glBindBufferRange(GL_SHADER_STORAGE_BUFFER, SHADER_PART_PRS_NR, m_PackedParticlesBufferHandle, pressureSSBOoffset, pressureSSBOsize);   /// Particle Pressure

    Log::logInitSucc(m_Name, "particle buffers");

就像我说的，一切正常，除了在40801粒子处，以下错误出现在我的日志中，并且某些缓冲区不再加载:

[APPLICATION]::  Bind particle buffers...
[APPLICATION]::  Init particle seeds ...
[APPLICATION]::  Save data in buffer ...

[SOURCE_API]::   [TYPE_OTHER][131185] [SEVERITY_NOTIFICATION] Buffer detailed info: Buffer object 3 (bound to GL_SHADER_STORAGE_BUFFER, usage hint is GL_STATIC_DRAW) will use VIDEO memory as the source for buffer object operations.

[APPLICATION]::  Init particle seeds SUCCESS!
[APPLICATION]::  Bind vertex array object (VAO) to buffer ...
[APPLICATION]::  Init VAO SUCCESS!
[APPLICATION]::  Bind particle buffers: positions
[APPLICATION]::  Bind particle buffers: velocities

[SOURCE_API]::   [TYPE_ERROR][1281] [SEVERITY_HIGH] GL_INVALID_VALUE error generated. <start> does not meet minimum alignment requirements for shader storage buffers.

[APPLICATION]::  Bind particle buffers: force

[SOURCE_API]::   [TYPE_ERROR][1281] [SEVERITY_HIGH] GL_INVALID_VALUE error generated. <start> does not meet minimum alignment requirements for shader storage buffers.

[APPLICATION]::  Bind particle buffers: density
[APPLICATION]::  Bind particle buffers: pressure

[SOURCE_API]::   [TYPE_ERROR][1281] [SEVERITY_HIGH] GL_INVALID_VALUE error generated. <start> does not meet minimum alignment requirements for shader storage buffers.

Answer 1

无法使用glBindBufferRange将任意偏移量寻址到缓冲区中。偏移量必须是相应缓冲区偏移量对齐的倍数，具体取决于所使用的缓冲区类型。此限制取决于平台，并且由GPU上的基础内存体系结构强加。

对于SSBO(在此使用)，可以使用以下代码查询相关的对齐方式:

glGetIntegeri_v(GL_SHADER_STORAGE_BUFFER_OFFSET_ALIGNMENT, &alignment);

可以在 OpenGL 4.6 Spec, Section 6.7.1中找到更多详细信息