diff options
Diffstat (limited to 'src/gallium/docs/source/context.rst')
| -rw-r--r-- | src/gallium/docs/source/context.rst | 61 |
1 files changed, 41 insertions, 20 deletions
diff --git a/src/gallium/docs/source/context.rst b/src/gallium/docs/source/context.rst index 391139fb0ef..b2872cd282f 100644 --- a/src/gallium/docs/source/context.rst +++ b/src/gallium/docs/source/context.rst @@ -54,8 +54,6 @@ buffers, surfaces) are bound to the driver. * ``set_index_buffer`` -* ``set_stream_output_buffers`` - Non-CSO State ^^^^^^^^^^^^^ @@ -139,6 +137,47 @@ cube, and 3d textures otherwise they are 0. * ``surface_destroy`` destroys a surface and releases its reference to the associated resource. +Stream output targets +^^^^^^^^^^^^^^^^^^^^^ + +Stream output, also known as transform feedback, allows writing the primitives +produced by the vertex pipeline to buffers. This is done after the geometry +shader or vertex shader if no geometry shader is present. + +The stream output targets are views into buffer resources which can be bound +as stream outputs and specify a memory range where it's valid to write +primitives. The pipe driver must implement memory protection such that any +primitives written outside of the specified memory range are discarded. + +Two stream output targets can use the same resource at the same time, but +with a disjoint memory range. + +Additionally, the stream output target internally maintains the offset +into the buffer which is incremented everytime something is written to it. +The internal offset is equal to how much data has already been written. +It can be stored in device memory and the CPU actually doesn't have to query +it. + +The stream output target can be used in a draw command to provide +the vertex count. The vertex count is derived from the internal offset +discussed above. + +* ``create_stream_output_target`` create a new target. + +* ``stream_output_target_destroy`` destroys a target. Users of this should + use pipe_so_target_reference instead. + +* ``set_stream_output_targets`` binds stream output targets. The parameter + append_bitmask is a bitmask, where the i-th bit specifies whether new + primitives should be appended to the i-th buffer (writing starts at + the internal offset), or whether writing should start at the beginning + (the internal offset is effectively set to 0). + +NOTE: The currently-bound vertex or geometry shader must be compiled with +the properly-filled-in structure pipe_stream_output_info describing which +outputs should be written to buffers and how. The structure is part of +pipe_shader_state. + Clearing ^^^^^^^^ @@ -394,24 +433,6 @@ The interfaces to these calls are likely to change to make it easier for a driver to batch multiple blits with the same source and destination. - -Stream Output -^^^^^^^^^^^^^ - -Stream output, also known as transform feedback allows writing the results of the -vertex pipeline (after the geometry shader or vertex shader if no geometry shader -is present) to be written to a buffer created with a ``PIPE_BIND_STREAM_OUTPUT`` -flag. - -First a stream output state needs to be created with the -``create_stream_output_state`` call. It specific the details of what's being written, -to which buffer and with what kind of a writemask. - -Then target buffers needs to be set with the call to ``set_stream_output_buffers`` -which sets the buffers and the offsets from the start of those buffer to where -the data will be written to. - - Transfers ^^^^^^^^^ |