SSBO std430 layout rules

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@GClements

Essentially, std140 was designed for hardware where a vec4 was the smallest addressable unit; anything else was just a vec4 with unused fields.

std430 relaxes those restrictions, allowing objects to be aligned to 1-word, 2-word or 4-word boundaries (but this still means that vec3s can’t be packed; the fourth word must be padding or a single float field).

Related to std140…

Have noticed that OpenGL GLSL support for std430 packing in Uniform Buffer Objects (UBOs) is finally available, for NVIDIA at least:

• GL_NV_uniform_buffer_std430_layout

It’s definitely in NVIDIA’s recent drivers, but I haven’t seen this new extension show up in the OpenGL Registry yet.

FWIW, Vulkan GLSL has std430 support for UBOs since ~2015, but OpenGL GLSL been stuck with std140 for UBOs until recently.

Related:

• Std430 layout for Uniform Blocks