VK_KHR_shader_draw_parameters(3) Manual Page

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This extension adds support for the following SPIR-V extension in Vulkan:

The extension provides access to three additional built-in shader variables in Vulkan:

When using GLSL source-based shader languages, the following variables from GL_ARB_shader_draw_parameters can map to these SPIR-V built-in decorations:

All functionality in this extension is included in core Vulkan 1.1. However, the shaderDrawParameters feature bit was added to distinguish whether it is actually available or not.

1) Is this the same functionality as GL_ARB_shader_draw_parameters?

RESOLVED: It is actually a superset, as it also adds in support for arrayed drawing commands.

In GL for GL_ARB_shader_draw_parameters, gl_BaseVertexARB holds the integer value passed to the parameter to the command that resulted in the current shader invocation. In the case where the command has no baseVertex parameter, the value of gl_BaseVertexARB is zero. This means that gl_BaseVertexARB = baseVertex (for glDrawElements commands with baseVertex) or 0. In particular there are no glDrawArrays commands that take a baseVertex parameter.

Now in Vulkan, we have BaseVertex = vertexOffset (for indexed drawing commands) or firstVertex (for arrayed drawing commands), and so Vulkan’s version is really a superset of GL functionality.

No cross-references are available

For more information, see the Vulkan Specification

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