一個粒子過多：生成了GL_INVALID_VALUE錯誤。 <start> 不滿足着色器存儲緩沖區的最低對齊要求

Question

我的粒子系統出現一個奇怪的錯誤。 我可以動態設置緩沖區的大小，並且可以根據需要更改粒子的數量。 我正在玩數字30k，40k及其之間的所有數字。 40800達到了最大值……然后我從輸出終端的標題中得到了錯誤。

這是代碼：

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");

就像我說的，一切正常，除了在40801粒子處，以下錯誤顯示在我的日志中，並且某些緩沖區不再加載：

[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

使用glBindBufferRange無法將任意偏移量尋址到緩沖區中。 偏移量必須是相應緩沖區偏移量對齊的倍數，具體取決於所使用的緩沖區類型。 此限制取決於平台，並且由GPU上的基礎內存體系結構強加。

對於SSBO（在此使用），可以使用以下代碼查詢相關的對齊方式：

glGetIntegeri_v(GL_SHADER_STORAGE_BUFFER_OFFSET_ALIGNMENT, &alignment);

可以在OpenGL 4.6規范的第6.7.1節中找到更多詳細信息。