+.. _context:
+
Context
=======
* :ref:`Depth, Stencil, & Alpha`: ``*_depth_stencil_alpha_state``
* :ref:`Shader`: These have two sets of methods. ``*_fs_state`` is for
fragment shaders, and ``*_vs_state`` is for vertex shaders.
+* :ref:`Vertex Elements`: ``*_vertex_elements_state``
Resource Binding State
are mostly restricted to the first one right now).
* ``set_framebuffer_state``
-* ``set_fragment_sampler_textures``
-* ``set_vertex_sampler_textures``
+
* ``set_vertex_buffers``
These pieces of state are too small, variable, and/or trivial to have CSO
objects. They all follow simple, one-method binding calls, e.g.
-``set_edgeflags``.
+``set_blend_color``.
+* ``set_stencil_ref`` sets the stencil front and back reference values
+ which are used as comparison values in stencil test.
* ``set_blend_color``
+* ``set_sample_mask``
* ``set_clip_state``
* ``set_polygon_stipple``
* ``set_scissor_state`` sets the bounds for the scissor test, which culls
not have the scissor test enabled, then the scissor bounds never need to
be set since they will not be used.
* ``set_viewport_state``
-* ``set_vertex_elements``
+
+
+Sampler Views
+^^^^^^^^^^^^^
+
+These are the means to bind textures to shader stages. To create one, specify
+its format, swizzle and LOD range in sampler view template.
+
+If texture format is different than template format, it is said the texture
+is being cast to another format. Casting can be done only between compatible
+formats, that is formats that have matching component order and sizes.
+
+Swizzle fields specify they way in which fetched texel components are placed
+in the result register. For example, ``swizzle_r`` specifies what is going to be
+placed in first component of result register.
+
+The ``first_level`` and ``last_level`` fields of sampler view template specify
+the LOD range the texture is going to be constrained to.
+
+* ``set_fragment_sampler_views`` binds an array of sampler views to
+ fragment shader stage. Every binding point acquires a reference
+ to a respective sampler view and releases a reference to the previous
+ sampler view.
+
+* ``set_vertex_sampler_views`` binds an array of sampler views to vertex
+ shader stage. Every binding point acquires a reference to a respective
+ sampler view and releases a reference to the previous sampler view.
+
+* ``create_sampler_view`` creates a new sampler view. ``texture`` is associated
+ with the sampler view which results in sampler view holding a reference
+ to the texture. Format specified in template must be compatible
+ with texture format.
+
+* ``sampler_view_destroy`` destroys a sampler view and releases its reference
+ to associated texture.
Clearing
^^^^^^^^
+Clear is one of the most difficult concepts to nail down to a single
+interface (due to both different requirements from APIs and also driver/hw
+specific differences).
+
``clear`` initializes some or all of the surfaces currently bound to
the framebuffer to particular RGBA, depth, or stencil values.
+Currently, this does not take into account color or stencil write masks (as
+used by GL), and always clears the whole surfaces (no scissoring as used by
+GL clear or explicit rectangles like d3d9 uses). It can, however, also clear
+only depth or stencil in a combined depth/stencil surface, if the driver
+supports PIPE_CAP_DEPTHSTENCIL_CLEAR_SEPARATE.
+If a surface includes several layers/slices (XXX: not yet...) then all layers
+will be cleared.
-Clear is one of the most difficult concepts to nail down to a single
-interface and it seems likely that we will want to add additional
-clear paths, for instance clearing surfaces not bound to the
-framebuffer, or read-modify-write clears such as depth-only or
-stencil-only clears of packed depth-stencil buffers.
+``clear_render_target`` clears a single color rendertarget with the specified
+color value. While it is only possible to clear one surface at a time (which can
+include several layers), this surface need not be bound to the framebuffer.
+
+``clear_depth_stencil`` clears a single depth, stencil or depth/stencil surface
+with the specified depth and stencil values (for combined depth/stencil buffers,
+is is also possible to only clear one or the other part). While it is only
+possible to clear one surface at a time (which can include several layers),
+this surface need not be bound to the framebuffer.
Drawing
If ``indexBuffer`` is NULL, the sequential numbers are used directly
as indices to fetch vertex attributes.
+``indexBias`` is a value which is added to every index read from the index
+buffer before fetching vertex attributes.
+
+``minIndex`` and ``maxIndex`` describe minimum and maximum index contained in
+the index buffer.
+
If a given vertex element has ``instance_divisor`` set to 0, it is said
it contains per-vertex data and effective vertex attribute address needs
to be recalculated for every index.
exercises this.
Queries can be created with ``create_query`` and deleted with
-``destroy_query``. To enable a query, use ``begin_query``, and when finished,
-use ``end_query`` to stop the query. Finally, ``get_query_result`` is used
-to retrieve the results.
+``destroy_query``. To start a query, use ``begin_query``, and when finished,
+use ``end_query`` to end the query.
+
+``get_query_result`` is used to retrieve the results of a query. If
+the ``wait`` parameter is TRUE, then the ``get_query_result`` call
+will block until the results of the query are ready (and TRUE will be
+returned). Otherwise, if the ``wait`` parameter is FALSE, the call
+will not block and the return value will be TRUE if the query has
+completed or FALSE otherwise.
+
+The most common type of query is the occlusion query,
+``PIPE_QUERY_OCCLUSION_COUNTER``, which counts the number of fragments which
+are written to the framebuffer without being culled by
+:ref:`Depth, Stencil, & Alpha` testing or shader KILL instructions.
+
+Another type of query, ``PIPE_QUERY_TIME_ELAPSED``, returns the amount of
+time, in nanoseconds, the context takes to perform operations.
-A common type of query is the occlusion query which counts the number of
-fragments/pixels which are written to the framebuffer (and not culled by
-Z/stencil/alpha testing or shader KILL instructions).
+Gallium does not guarantee the availability of any query types; one must
+always check the capabilities of the :ref:`Screen` first.
Conditional Rendering
Resource Busy Queries
^^^^^^^^^^^^^^^^^^^^^
-``is_texture_referenced``
-
-``is_buffer_referenced``
+``is_resource_referenced``
Blitting
^^^^^^^^
-These methods emulate classic blitter controls. They are not guaranteed to be
-available; if they are set to NULL, then they are not present.
+These methods emulate classic blitter controls.
-These methods operate directly on ``pipe_surface`` objects, and stand
+These methods operate directly on ``pipe_resource`` objects, and stand
apart from any 3D state in the context. Blitting functionality may be
moved to a separate abstraction at some point in the future.
-``surface_fill`` performs a fill operation on a section of a surface.
+``resource_copy_region`` blits a region of a subresource of a resource to a
+region of another subresource of a resource, provided that both resources have the
+same format. The source and destination may be the same resource, but overlapping
+blits are not permitted.
-``surface_copy`` blits a region of a surface to a region of another surface,
-provided that both surfaces are the same format. The source and destination
-may be the same surface, and overlapping blits are permitted.
+``resource_resolve`` resolves a multisampled resource into a non-multisampled
+one. Formats and dimensions must match. This function must be present if a driver
+supports multisampling.
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
+^^^^^^^^^
+
+These methods are used to get data to/from a resource.
+
+``get_transfer`` creates a transfer object.
+
+``transfer_destroy`` destroys the transfer object. May cause
+data to be written to the resource at this point.
+
+``transfer_map`` creates a memory mapping for the transfer object.
+The returned map points to the start of the mapped range according to
+the box region, not the beginning of the resource.
+
+``transfer_unmap`` remove the memory mapping for the transfer object.
+Any pointers into the map should be considered invalid and discarded.
+
+``transfer_inline_write`` performs a simplified transfer for simple writes.
+Basically get_transfer, transfer_map, data write, transfer_unmap, and
+transfer_destroy all in one.
+
+.. _transfer_flush_region:
+
+transfer_flush_region
+%%%%%%%%%%%%%%%%%%%%%
+
+If a transfer was created with ``FLUSH_EXPLICIT``, it will not automatically
+be flushed on write or unmap. Flushes must be requested with
+``transfer_flush_region``. Flush ranges are relative to the mapped range, not
+the beginning of the resource.
+
+.. _pipe_transfer:
+
+PIPE_TRANSFER
+^^^^^^^^^^^^^
+
+These flags control the behavior of a transfer object.
+
+* ``READ``: resource contents are read at transfer create time.
+* ``WRITE``: resource contents will be written back at transfer destroy time.
+* ``MAP_DIRECTLY``: a transfer should directly map the resource. May return
+ NULL if not supported.
+* ``DISCARD``: The memory within the mapped region is discarded.
+ Cannot be used with ``READ``.
+* ``DONTBLOCK``: Fail if the resource cannot be mapped immediately.
+* ``UNSYNCHRONIZED``: Do not synchronize pending operations on the resource
+ when mapping. The interaction of any writes to the map and any
+ operations pending on the resource are undefined. Cannot be used with
+ ``READ``.
+* ``FLUSH_EXPLICIT``: Written ranges will be notified later with
+ :ref:`transfer_flush_region`. Cannot be used with ``READ``.
projects / mesa.git / blobdiff