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      1 .. _screen:
      2 
      3 Screen
      4 ======
      5 
      6 A screen is an object representing the context-independent part of a device.
      7 
      8 Flags and enumerations
      9 ----------------------
     10 
     11 XXX some of these don't belong in this section.
     12 
     13 
     14 .. _pipe_cap:
     15 
     16 PIPE_CAP_*
     17 ^^^^^^^^^^
     18 
     19 Capability queries return information about the features and limits of the
     20 driver/GPU.  For floating-point values, use :ref:`get_paramf`, and for boolean
     21 or integer values, use :ref:`get_param`.
     22 
     23 The integer capabilities:
     24 
     25 * ``PIPE_CAP_NPOT_TEXTURES``: Whether :term:`NPOT` textures may have repeat modes,
     26   normalized coordinates, and mipmaps.
     27 * ``PIPE_CAP_TWO_SIDED_STENCIL``: Whether the stencil test can also affect back-facing
     28   polygons.
     29 * ``PIPE_CAP_MAX_DUAL_SOURCE_RENDER_TARGETS``: How many dual-source blend RTs are support.
     30   :ref:`Blend` for more information.
     31 * ``PIPE_CAP_ANISOTROPIC_FILTER``: Whether textures can be filtered anisotropically.
     32 * ``PIPE_CAP_POINT_SPRITE``: Whether point sprites are available.
     33 * ``PIPE_CAP_MAX_RENDER_TARGETS``: The maximum number of render targets that may be
     34   bound.
     35 * ``PIPE_CAP_OCCLUSION_QUERY``: Whether occlusion queries are available.
     36 * ``PIPE_CAP_QUERY_TIME_ELAPSED``: Whether PIPE_QUERY_TIME_ELAPSED queries are available.
     37 * ``PIPE_CAP_TEXTURE_SHADOW_MAP``: indicates whether the fragment shader hardware
     38   can do the depth texture / Z comparison operation in TEX instructions
     39   for shadow testing.
     40 * ``PIPE_CAP_TEXTURE_SWIZZLE``: Whether swizzling through sampler views is
     41   supported.
     42 * ``PIPE_CAP_MAX_TEXTURE_2D_LEVELS``: The maximum number of mipmap levels available
     43   for a 2D texture.
     44 * ``PIPE_CAP_MAX_TEXTURE_3D_LEVELS``: The maximum number of mipmap levels available
     45   for a 3D texture.
     46 * ``PIPE_CAP_MAX_TEXTURE_CUBE_LEVELS``: The maximum number of mipmap levels available
     47   for a cubemap.
     48 * ``PIPE_CAP_TEXTURE_MIRROR_CLAMP``: Whether mirrored texture coordinates with clamp
     49   are supported.
     50 * ``PIPE_CAP_BLEND_EQUATION_SEPARATE``: Whether alpha blend equations may be different
     51   from color blend equations, in :ref:`Blend` state.
     52 * ``PIPE_CAP_SM3``: Whether the vertex shader and fragment shader support equivalent
     53   opcodes to the Shader Model 3 specification. XXX oh god this is horrible
     54 * ``PIPE_CAP_MAX_STREAM_OUTPUT_BUFFERS``: The maximum number of stream buffers.
     55 * ``PIPE_CAP_PRIMITIVE_RESTART``: Whether primitive restart is supported.
     56 * ``PIPE_CAP_INDEP_BLEND_ENABLE``: Whether per-rendertarget blend enabling and channel
     57   masks are supported. If 0, then the first rendertarget's blend mask is
     58   replicated across all MRTs.
     59 * ``PIPE_CAP_INDEP_BLEND_FUNC``: Whether per-rendertarget blend functions are
     60   available. If 0, then the first rendertarget's blend functions affect all
     61   MRTs.
     62 * ``PIPE_CAP_MAX_TEXTURE_ARRAY_LAYERS``: The maximum number of texture array
     63   layers supported. If 0, the array textures are not supported at all and
     64   the ARRAY texture targets are invalid.
     65 * ``PIPE_CAP_TGSI_FS_COORD_ORIGIN_UPPER_LEFT``: Whether the TGSI property
     66   FS_COORD_ORIGIN with value UPPER_LEFT is supported.
     67 * ``PIPE_CAP_TGSI_FS_COORD_ORIGIN_LOWER_LEFT``: Whether the TGSI property
     68   FS_COORD_ORIGIN with value LOWER_LEFT is supported.
     69 * ``PIPE_CAP_TGSI_FS_COORD_PIXEL_CENTER_HALF_INTEGER``: Whether the TGSI
     70   property FS_COORD_PIXEL_CENTER with value HALF_INTEGER is supported.
     71 * ``PIPE_CAP_TGSI_FS_COORD_PIXEL_CENTER_INTEGER``: Whether the TGSI
     72   property FS_COORD_PIXEL_CENTER with value INTEGER is supported.
     73 * ``PIPE_CAP_DEPTH_CLIP_DISABLE``: Whether the driver is capable of disabling
     74   depth clipping (through pipe_rasterizer_state)
     75 * ``PIPE_CAP_SHADER_STENCIL_EXPORT``: Whether a stencil reference value can be
     76   written from a fragment shader.
     77 * ``PIPE_CAP_TGSI_INSTANCEID``: Whether TGSI_SEMANTIC_INSTANCEID is supported
     78   in the vertex shader.
     79 * ``PIPE_CAP_VERTEX_ELEMENT_INSTANCE_DIVISOR``: Whether the driver supports
     80   per-instance vertex attribs.
     81 * ``PIPE_CAP_FRAGMENT_COLOR_CLAMPED``: Whether fragment color clamping is
     82   supported.  That is, is the pipe_rasterizer_state::clamp_fragment_color
     83   flag supported by the driver?  If not, the state tracker will insert
     84   clamping code into the fragment shaders when needed.
     85 
     86 * ``PIPE_CAP_MIXED_COLORBUFFER_FORMATS``: Whether mixed colorbuffer formats are
     87   supported, e.g. RGBA8 and RGBA32F as the first and second colorbuffer, resp.
     88 * ``PIPE_CAP_VERTEX_COLOR_UNCLAMPED``: Whether the driver is capable of
     89   outputting unclamped vertex colors from a vertex shader. If unsupported,
     90   the vertex colors are always clamped. This is the default for DX9 hardware.
     91 * ``PIPE_CAP_VERTEX_COLOR_CLAMPED``: Whether the driver is capable of
     92   clamping vertex colors when they come out of a vertex shader, as specified
     93   by the pipe_rasterizer_state::clamp_vertex_color flag.  If unsupported,
     94   the vertex colors are never clamped. This is the default for DX10 hardware.
     95   If both clamped and unclamped CAPs are supported, the clamping can be
     96   controlled through pipe_rasterizer_state.  If the driver cannot do vertex
     97   color clamping, the state tracker may insert clamping code into the vertex
     98   shader.
     99 * ``PIPE_CAP_GLSL_FEATURE_LEVEL``: Whether the driver supports features
    100   equivalent to a specific GLSL version. E.g. for GLSL 1.3, report 130.
    101 * ``PIPE_CAP_QUADS_FOLLOW_PROVOKING_VERTEX_CONVENTION``: Whether quads adhere to
    102   the flatshade_first setting in ``pipe_rasterizer_state``.
    103 * ``PIPE_CAP_USER_VERTEX_BUFFERS``: Whether the driver supports user vertex
    104   buffers.  If not, the state tracker must upload all data which is not in hw
    105   resources.  If user-space buffers are supported, the driver must also still
    106   accept HW resource buffers.
    107 * ``PIPE_CAP_VERTEX_BUFFER_OFFSET_4BYTE_ALIGNED_ONLY``: This CAP describes a hw
    108   limitation.  If true, pipe_vertex_buffer::buffer_offset must always be aligned
    109   to 4.  If false, there are no restrictions on the offset.
    110 * ``PIPE_CAP_VERTEX_BUFFER_STRIDE_4BYTE_ALIGNED_ONLY``: This CAP describes a hw
    111   limitation.  If true, pipe_vertex_buffer::stride must always be aligned to 4.
    112   If false, there are no restrictions on the stride.
    113 * ``PIPE_CAP_VERTEX_ELEMENT_SRC_OFFSET_4BYTE_ALIGNED_ONLY``: This CAP describes
    114   a hw limitation.  If true, pipe_vertex_element::src_offset must always be
    115   aligned to 4.  If false, there are no restrictions on src_offset.
    116 * ``PIPE_CAP_COMPUTE``: Whether the implementation supports the
    117   compute entry points defined in pipe_context and pipe_screen.
    118 * ``PIPE_CAP_USER_INDEX_BUFFERS``: Whether user index buffers are supported.
    119   If not, the state tracker must upload all indices which are not in hw
    120   resources.  If user-space buffers are supported, the driver must also still
    121   accept HW resource buffers.
    122 * ``PIPE_CAP_USER_CONSTANT_BUFFERS``: Whether user-space constant buffers
    123   are supported.  If not, the state tracker must put constants into HW
    124   resources/buffers.  If user-space constant buffers are supported, the
    125   driver must still accept HW constant buffers also.
    126 * ``PIPE_CAP_CONSTANT_BUFFER_OFFSET_ALIGNMENT``: Describes the required
    127   alignment of pipe_constant_buffer::buffer_offset.
    128 * ``PIPE_CAP_START_INSTANCE``: Whether the driver supports
    129   pipe_draw_info::start_instance.
    130 * ``PIPE_CAP_QUERY_TIMESTAMP``: Whether PIPE_QUERY_TIMESTAMP and
    131   the pipe_screen::get_timestamp hook are implemented.
    132 * ``PIPE_CAP_TEXTURE_MULTISAMPLE``: Whether all MSAA resources supported
    133   for rendering are also supported for texturing.
    134 * ``PIPE_CAP_MIN_MAP_BUFFER_ALIGNMENT``: The minimum alignment that should be
    135   expected for a pointer returned by transfer_map if the resource is
    136   PIPE_BUFFER. In other words, the pointer returned by transfer_map is
    137   always aligned to this value.
    138 * ``PIPE_CAP_TEXTURE_BUFFER_OFFSET_ALIGNMENT``: Describes the required
    139   alignment for pipe_sampler_view::u.buf.offset, in bytes.
    140   If a driver does not support offset/size, it should return 0.
    141 * ``PIPE_CAP_BUFFER_SAMPLER_VIEW_RGBA_ONLY``: Whether the driver only
    142   supports R, RG, RGB and RGBA formats for PIPE_BUFFER sampler views.
    143   When this is the case it should be assumed that the swizzle parameters
    144   in the sampler view have no effect.
    145 * ``PIPE_CAP_TGSI_TEXCOORD``: This CAP describes a hw limitation.
    146   If true, the hardware cannot replace arbitrary shader inputs with sprite
    147   coordinates and hence the inputs that are desired to be replaceable must
    148   be declared with TGSI_SEMANTIC_TEXCOORD instead of TGSI_SEMANTIC_GENERIC.
    149   The rasterizer's sprite_coord_enable state therefore also applies to the
    150   TEXCOORD semantic.
    151   Also, TGSI_SEMANTIC_PCOORD becomes available, which labels a fragment shader
    152   input that will always be replaced with sprite coordinates.
    153 * ``PIPE_CAP_PREFER_BLIT_BASED_TEXTURE_TRANSFER``: Whether it is preferable
    154   to use a blit to implement a texture transfer which needs format conversions
    155   and swizzling in state trackers. Generally, all hardware drivers with
    156   dedicated memory should return 1 and all software rasterizers should return 0.
    157 * ``PIPE_CAP_QUERY_PIPELINE_STATISTICS``: Whether PIPE_QUERY_PIPELINE_STATISTICS
    158   is supported.
    159 * ``PIPE_CAP_TEXTURE_BORDER_COLOR_QUIRK``: Bitmask indicating whether special
    160   considerations have to be given to the interaction between the border color
    161   in the sampler object and the sampler view used with it.
    162   If PIPE_QUIRK_TEXTURE_BORDER_COLOR_SWIZZLE_R600 is set, the border color
    163   may be affected in undefined ways for any kind of permutational swizzle
    164   (any swizzle XYZW where X/Y/Z/W are not ZERO, ONE, or R/G/B/A respectively)
    165   in the sampler view.
    166   If PIPE_QUIRK_TEXTURE_BORDER_COLOR_SWIZZLE_NV50 is set, the border color
    167   state should be swizzled manually according to the swizzle in the sampler
    168   view it is intended to be used with, or herein undefined results may occur
    169   for permutational swizzles.
    170 * ``PIPE_CAP_MAX_TEXTURE_BUFFER_SIZE``: The maximum accessible size with
    171   a buffer sampler view, in texels.
    172 * ``PIPE_CAP_MAX_VIEWPORTS``: The maximum number of viewports (and scissors
    173   since they are linked) a driver can support. Returning 0 is equivalent
    174   to returning 1 because every driver has to support at least a single
    175   viewport/scissor combination.
    176 * ``PIPE_CAP_ENDIANNESS``:: The endianness of the device.  Either
    177   PIPE_ENDIAN_BIG or PIPE_ENDIAN_LITTLE.
    178 * ``PIPE_CAP_MIXED_FRAMEBUFFER_SIZES``: Whether it is allowed to have
    179   different sizes for fb color/zs attachments. This controls whether
    180   ARB_framebuffer_object is provided.
    181 * ``PIPE_CAP_TGSI_VS_LAYER_VIEWPORT``: Whether ``TGSI_SEMANTIC_LAYER`` and
    182   ``TGSI_SEMANTIC_VIEWPORT_INDEX`` are supported as vertex shader
    183   outputs. Note that the viewport will only be used if multiple viewports are
    184   exposed.
    185 * ``PIPE_CAP_MAX_GEOMETRY_OUTPUT_VERTICES``: The maximum number of vertices
    186   output by a single invocation of a geometry shader.
    187 * ``PIPE_CAP_MAX_GEOMETRY_TOTAL_OUTPUT_COMPONENTS``: The maximum number of
    188   vertex components output by a single invocation of a geometry shader.
    189   This is the product of the number of attribute components per vertex and
    190   the number of output vertices.
    191 * ``PIPE_CAP_MAX_TEXTURE_GATHER_COMPONENTS``: Max number of components
    192   in format that texture gather can operate on. 1 == RED, ALPHA etc,
    193   4 == All formats.
    194 * ``PIPE_CAP_TEXTURE_GATHER_SM5``: Whether the texture gather
    195   hardware implements the SM5 features, component selection,
    196   shadow comparison, and run-time offsets.
    197 * ``PIPE_CAP_BUFFER_MAP_PERSISTENT_COHERENT``: Whether
    198   PIPE_TRANSFER_PERSISTENT and PIPE_TRANSFER_COHERENT are supported
    199   for buffers.
    200 * ``PIPE_CAP_TEXTURE_QUERY_LOD``: Whether the ``LODQ`` instruction is
    201   supported.
    202 * ``PIPE_CAP_MIN_TEXTURE_GATHER_OFFSET``: The minimum offset that can be used
    203   in conjunction with a texture gather opcode.
    204 * ``PIPE_CAP_MAX_TEXTURE_GATHER_OFFSET``: The maximum offset that can be used
    205   in conjunction with a texture gather opcode.
    206 * ``PIPE_CAP_SAMPLE_SHADING``: Whether there is support for per-sample
    207   shading. The context->set_min_samples function will be expected to be
    208   implemented.
    209 * ``PIPE_CAP_TEXTURE_GATHER_OFFSETS``: Whether the ``TG4`` instruction can
    210   accept 4 offsets.
    211 * ``PIPE_CAP_TGSI_VS_WINDOW_SPACE_POSITION``: Whether
    212   TGSI_PROPERTY_VS_WINDOW_SPACE_POSITION is supported, which disables clipping
    213   and viewport transformation.
    214 * ``PIPE_CAP_MAX_VERTEX_STREAMS``: The maximum number of vertex streams
    215   supported by the geometry shader. If stream-out is supported, this should be
    216   at least 1. If stream-out is not supported, this should be 0.
    217 * ``PIPE_CAP_DRAW_INDIRECT``: Whether the driver supports taking draw arguments
    218   { count, instance_count, start, index_bias } from a PIPE_BUFFER resource.
    219   See pipe_draw_info.
    220 * ``PIPE_CAP_MULTI_DRAW_INDIRECT``: Whether the driver supports
    221   pipe_draw_info::indirect_stride and ::indirect_count
    222 * ``PIPE_CAP_MULTI_DRAW_INDIRECT_PARAMS``: Whether the driver supports
    223   taking the number of indirect draws from a separate parameter
    224   buffer, see pipe_draw_info::indirect_params.
    225 * ``PIPE_CAP_TGSI_FS_FINE_DERIVATIVE``: Whether the fragment shader supports
    226   the FINE versions of DDX/DDY.
    227 * ``PIPE_CAP_VENDOR_ID``: The vendor ID of the underlying hardware. If it's
    228   not available one should return 0xFFFFFFFF.
    229 * ``PIPE_CAP_DEVICE_ID``: The device ID (PCI ID) of the underlying hardware.
    230   0xFFFFFFFF if not available.
    231 * ``PIPE_CAP_ACCELERATED``: Whether the renderer is hardware accelerated.
    232 * ``PIPE_CAP_VIDEO_MEMORY``: The amount of video memory in megabytes.
    233 * ``PIPE_CAP_UMA``: If the device has a unified memory architecture or on-card
    234   memory and GART.
    235 * ``PIPE_CAP_CONDITIONAL_RENDER_INVERTED``: Whether the driver supports inverted
    236   condition for conditional rendering.
    237 * ``PIPE_CAP_MAX_VERTEX_ATTRIB_STRIDE``: The maximum supported vertex stride.
    238 * ``PIPE_CAP_SAMPLER_VIEW_TARGET``: Whether the sampler view's target can be
    239   different than the underlying resource's, as permitted by
    240   ARB_texture_view. For example a 2d array texture may be reinterpreted as a
    241   cube (array) texture and vice-versa.
    242 * ``PIPE_CAP_CLIP_HALFZ``: Whether the driver supports the
    243   pipe_rasterizer_state::clip_halfz being set to true. This is required
    244   for enabling ARB_clip_control.
    245 * ``PIPE_CAP_VERTEXID_NOBASE``: If true, the driver only supports
    246   TGSI_SEMANTIC_VERTEXID_NOBASE (and not TGSI_SEMANTIC_VERTEXID). This means
    247   state trackers for APIs whose vertexIDs are offset by basevertex (such as GL)
    248   will need to lower TGSI_SEMANTIC_VERTEXID to TGSI_SEMANTIC_VERTEXID_NOBASE
    249   and TGSI_SEMANTIC_BASEVERTEX, so drivers setting this must handle both these
    250   semantics. Only relevant if geometry shaders are supported.
    251   (BASEVERTEX could be exposed separately too via ``PIPE_CAP_DRAW_PARAMETERS``).
    252 * ``PIPE_CAP_POLYGON_OFFSET_CLAMP``: If true, the driver implements support
    253   for ``pipe_rasterizer_state::offset_clamp``.
    254 * ``PIPE_CAP_MULTISAMPLE_Z_RESOLVE``: Whether the driver supports blitting
    255   a multisampled depth buffer into a single-sampled texture (or depth buffer).
    256   Only the first sampled should be copied.
    257 * ``PIPE_CAP_RESOURCE_FROM_USER_MEMORY``: Whether the driver can create
    258   a pipe_resource where an already-existing piece of (malloc'd) user memory
    259   is used as its backing storage. In other words, whether the driver can map
    260   existing user memory into the device address space for direct device access.
    261   The create function is pipe_screen::resource_from_user_memory. The address
    262   and size must be page-aligned.
    263 * ``PIPE_CAP_DEVICE_RESET_STATUS_QUERY``:
    264   Whether pipe_context::get_device_reset_status is implemented.
    265 * ``PIPE_CAP_MAX_SHADER_PATCH_VARYINGS``:
    266   How many per-patch outputs and inputs are supported between tessellation
    267   control and tessellation evaluation shaders, not counting in TESSINNER and
    268   TESSOUTER. The minimum allowed value for OpenGL is 30.
    269 * ``PIPE_CAP_TEXTURE_FLOAT_LINEAR``: Whether the linear minification and
    270   magnification filters are supported with single-precision floating-point
    271   textures.
    272 * ``PIPE_CAP_TEXTURE_HALF_FLOAT_LINEAR``: Whether the linear minification and
    273   magnification filters are supported with half-precision floating-point
    274   textures.
    275 * ``PIPE_CAP_DEPTH_BOUNDS_TEST``: Whether bounds_test, bounds_min, and
    276   bounds_max states of pipe_depth_stencil_alpha_state behave according
    277   to the GL_EXT_depth_bounds_test specification.
    278 * ``PIPE_CAP_TGSI_TXQS``: Whether the `TXQS` opcode is supported
    279 * ``PIPE_CAP_FORCE_PERSAMPLE_INTERP``: If the driver can force per-sample
    280   interpolation for all fragment shader inputs if
    281   pipe_rasterizer_state::force_persample_interp is set. This is only used
    282   by GL3-level sample shading (ARB_sample_shading). GL4-level sample shading
    283   (ARB_gpu_shader5) doesn't use this. While GL3 hardware has a state for it,
    284   GL4 hardware will likely need to emulate it with a shader variant, or by
    285   selecting the interpolation weights with a conditional assignment
    286   in the shader.
    287 * ``PIPE_CAP_SHAREABLE_SHADERS``: Whether shader CSOs can be used by any
    288   pipe_context.
    289 * ``PIPE_CAP_COPY_BETWEEN_COMPRESSED_AND_PLAIN_FORMATS``:
    290   Whether copying between compressed and plain formats is supported where
    291   a compressed block is copied to/from a plain pixel of the same size.
    292 * ``PIPE_CAP_CLEAR_TEXTURE``: Whether `clear_texture` will be
    293   available in contexts.
    294 * ``PIPE_CAP_DRAW_PARAMETERS``: Whether ``TGSI_SEMANTIC_BASEVERTEX``,
    295   ``TGSI_SEMANTIC_BASEINSTANCE``, and ``TGSI_SEMANTIC_DRAWID`` are
    296   supported in vertex shaders.
    297 * ``PIPE_CAP_TGSI_PACK_HALF_FLOAT``: Whether the ``UP2H`` and ``PK2H``
    298   TGSI opcodes are supported.
    299 * ``PIPE_CAP_TGSI_FS_POSITION_IS_SYSVAL``: If state trackers should use
    300   a system value for the POSITION fragment shader input.
    301 * ``PIPE_CAP_TGSI_FS_FACE_IS_INTEGER_SYSVAL``: If state trackers should use
    302   a system value for the FACE fragment shader input.
    303   Also, the FACE system value is integer, not float.
    304 * ``PIPE_CAP_SHADER_BUFFER_OFFSET_ALIGNMENT``: Describes the required
    305   alignment for pipe_shader_buffer::buffer_offset, in bytes. Maximum
    306   value allowed is 256 (for GL conformance). 0 is only allowed if
    307   shader buffers are not supported.
    308 * ``PIPE_CAP_INVALIDATE_BUFFER``: Whether the use of ``invalidate_resource``
    309   for buffers is supported.
    310 * ``PIPE_CAP_GENERATE_MIPMAP``: Indicates whether pipe_context::generate_mipmap
    311   is supported.
    312 * ``PIPE_CAP_STRING_MARKER``: Whether pipe->emit_string_marker() is supported.
    313 * ``PIPE_CAP_SURFACE_REINTERPRET_BLOCKS``: Indicates whether
    314   pipe_context::create_surface supports reinterpreting a texture as a surface
    315   of a format with different block width/height (but same block size in bits).
    316   For example, a compressed texture image can be interpreted as a
    317   non-compressed surface whose texels are the same number of bits as the
    318   compressed blocks, and vice versa. The width and height of the surface is
    319   adjusted appropriately.
    320 * ``PIPE_CAP_QUERY_BUFFER_OBJECT``: Driver supports
    321   context::get_query_result_resource callback.
    322 * ``PIPE_CAP_PCI_GROUP``: Return the PCI segment group number.
    323 * ``PIPE_CAP_PCI_BUS``: Return the PCI bus number.
    324 * ``PIPE_CAP_PCI_DEVICE``: Return the PCI device number.
    325 * ``PIPE_CAP_PCI_FUNCTION``: Return the PCI function number.
    326 * ``PIPE_CAP_FRAMEBUFFER_NO_ATTACHMENT``:
    327   If non-zero, rendering to framebuffers with no surface attachments
    328   is supported. The context->is_format_supported function will be expected
    329   to be implemented with PIPE_FORMAT_NONE yeilding the MSAA modes the hardware
    330   supports. N.B., The maximum number of layers supported for rasterizing a
    331   primitive on a layer is obtained from ``PIPE_CAP_MAX_TEXTURE_ARRAY_LAYERS``
    332   even though it can be larger than the number of layers supported by either
    333   rendering or textures.
    334 * ``PIPE_CAP_ROBUST_BUFFER_ACCESS_BEHAVIOR``: Implementation uses bounds
    335   checking on resource accesses by shader if the context is created with
    336   PIPE_CONTEXT_ROBUST_BUFFER_ACCESS. See the ARB_robust_buffer_access_behavior
    337   extension for information on the required behavior for out of bounds accesses
    338   and accesses to unbound resources.
    339 * ``PIPE_CAP_CULL_DISTANCE``: Whether the driver supports the arb_cull_distance
    340   extension and thus implements proper support for culling planes.
    341 * ``PIPE_CAP_PRIMITIVE_RESTART_FOR_PATCHES``: Whether primitive restart is
    342   supported for patch primitives.
    343 * ``PIPE_CAP_TGSI_VOTE``: Whether the ``VOTE_*`` ops can be used in shaders.
    344 * ``PIPE_CAP_MAX_WINDOW_RECTANGLES``: The maxium number of window rectangles
    345   supported in ``set_window_rectangles``.
    346 * ``PIPE_CAP_POLYGON_OFFSET_UNITS_UNSCALED``: If true, the driver implements support
    347   for ``pipe_rasterizer_state::offset_units_unscaled``.
    348 * ``PIPE_CAP_VIEWPORT_SUBPIXEL_BITS``: Number of bits of subpixel precision for
    349   floating point viewport bounds.
    350 * ``PIPE_CAP_MIXED_COLOR_DEPTH_BITS``: Whether there is non-fallback
    351   support for color/depth format combinations that use a different
    352   number of bits. For the purpose of this cap, Z24 is treated as
    353   32-bit. If set to off, that means that a B5G6R5 + Z24 or RGBA8 + Z16
    354   combination will require a driver fallback, and should not be
    355   advertised in the GLX/EGL config list.
    356 * ``PIPE_CAP_TGSI_ARRAY_COMPONENTS``: If true, the driver interprets the
    357   UsageMask of input and output declarations and allows declaring arrays
    358   in overlapping ranges. The components must be a contiguous range, e.g. a
    359   UsageMask of  xy or yzw is allowed, but xz or yw isn't. Declarations with
    360   overlapping locations must have matching semantic names and indices, and
    361   equal interpolation qualifiers.
    362   Components may overlap, notably when the gaps in an array of dvec3 are
    363   filled in.
    364 * ``PIPE_CAP_STREAM_OUTPUT_INTERLEAVE_BUFFERS``: Whether interleaved stream
    365   output mode is able to interleave across buffers. This is required for
    366   ARB_transform_feedback3.
    367 * ``PIPE_CAP_TGSI_CAN_READ_OUTPUTS``: Whether every TGSI shader stage can read
    368   from the output file.
    369 * ``PIPE_CAP_GLSL_OPTIMIZE_CONSERVATIVELY``: Tell the GLSL compiler to use
    370   the minimum amount of optimizations just to be able to do all the linking
    371   and lowering.
    372 * ``PIPE_CAP_TGSI_FS_FBFETCH``: Whether a fragment shader can use the FBFETCH
    373   opcode to retrieve the current value in the framebuffer.
    374 
    375 
    376 .. _pipe_capf:
    377 
    378 PIPE_CAPF_*
    379 ^^^^^^^^^^^^^^^^
    380 
    381 The floating-point capabilities are:
    382 
    383 * ``PIPE_CAPF_MAX_LINE_WIDTH``: The maximum width of a regular line.
    384 * ``PIPE_CAPF_MAX_LINE_WIDTH_AA``: The maximum width of a smoothed line.
    385 * ``PIPE_CAPF_MAX_POINT_WIDTH``: The maximum width and height of a point.
    386 * ``PIPE_CAPF_MAX_POINT_WIDTH_AA``: The maximum width and height of a smoothed point.
    387 * ``PIPE_CAPF_MAX_TEXTURE_ANISOTROPY``: The maximum level of anisotropy that can be
    388   applied to anisotropically filtered textures.
    389 * ``PIPE_CAPF_MAX_TEXTURE_LOD_BIAS``: The maximum :term:`LOD` bias that may be applied
    390   to filtered textures.
    391 * ``PIPE_CAPF_GUARD_BAND_LEFT``,
    392   ``PIPE_CAPF_GUARD_BAND_TOP``,
    393   ``PIPE_CAPF_GUARD_BAND_RIGHT``,
    394   ``PIPE_CAPF_GUARD_BAND_BOTTOM``: TODO
    395 
    396 
    397 .. _pipe_shader_cap:
    398 
    399 PIPE_SHADER_CAP_*
    400 ^^^^^^^^^^^^^^^^^
    401 
    402 These are per-shader-stage capabitity queries. Different shader stages may
    403 support different features.
    404 
    405 * ``PIPE_SHADER_CAP_MAX_INSTRUCTIONS``: The maximum number of instructions.
    406 * ``PIPE_SHADER_CAP_MAX_ALU_INSTRUCTIONS``: The maximum number of arithmetic instructions.
    407 * ``PIPE_SHADER_CAP_MAX_TEX_INSTRUCTIONS``: The maximum number of texture instructions.
    408 * ``PIPE_SHADER_CAP_MAX_TEX_INDIRECTIONS``: The maximum number of texture indirections.
    409 * ``PIPE_SHADER_CAP_MAX_CONTROL_FLOW_DEPTH``: The maximum nested control flow depth.
    410 * ``PIPE_SHADER_CAP_MAX_INPUTS``: The maximum number of input registers.
    411 * ``PIPE_SHADER_CAP_MAX_OUTPUTS``: The maximum number of output registers.
    412   This is valid for all shaders except the fragment shader.
    413 * ``PIPE_SHADER_CAP_MAX_CONST_BUFFER_SIZE``: The maximum size per constant buffer in bytes.
    414 * ``PIPE_SHADER_CAP_MAX_CONST_BUFFERS``: Maximum number of constant buffers that can be bound
    415   to any shader stage using ``set_constant_buffer``. If 0 or 1, the pipe will
    416   only permit binding one constant buffer per shader, and the shaders will
    417   not permit two-dimensional access to constants.
    418 
    419 If a value greater than 0 is returned, the driver can have multiple
    420 constant buffers bound to shader stages. The CONST register file can
    421 be accessed with two-dimensional indices, like in the example below.
    422 
    423 DCL CONST[0][0..7]       # declare first 8 vectors of constbuf 0
    424 DCL CONST[3][0]          # declare first vector of constbuf 3
    425 MOV OUT[0], CONST[0][3]  # copy vector 3 of constbuf 0
    426 
    427 For backwards compatibility, one-dimensional access to CONST register
    428 file is still supported. In that case, the constbuf index is assumed
    429 to be 0.
    430 
    431 * ``PIPE_SHADER_CAP_MAX_TEMPS``: The maximum number of temporary registers.
    432 * ``PIPE_SHADER_CAP_MAX_PREDS``: The maximum number of predicate registers.
    433 * ``PIPE_SHADER_CAP_TGSI_CONT_SUPPORTED``: Whether the continue opcode is supported.
    434 * ``PIPE_SHADER_CAP_INDIRECT_INPUT_ADDR``: Whether indirect addressing
    435   of the input file is supported.
    436 * ``PIPE_SHADER_CAP_INDIRECT_OUTPUT_ADDR``: Whether indirect addressing
    437   of the output file is supported.
    438 * ``PIPE_SHADER_CAP_INDIRECT_TEMP_ADDR``: Whether indirect addressing
    439   of the temporary file is supported.
    440 * ``PIPE_SHADER_CAP_INDIRECT_CONST_ADDR``: Whether indirect addressing
    441   of the constant file is supported.
    442 * ``PIPE_SHADER_CAP_SUBROUTINES``: Whether subroutines are supported, i.e.
    443   BGNSUB, ENDSUB, CAL, and RET, including RET in the main block.
    444 * ``PIPE_SHADER_CAP_INTEGERS``: Whether integer opcodes are supported.
    445   If unsupported, only float opcodes are supported.
    446 * ``PIPE_SHADER_CAP_MAX_TEXTURE_SAMPLERS``: The maximum number of texture
    447   samplers.
    448 * ``PIPE_SHADER_CAP_PREFERRED_IR``: Preferred representation of the
    449   program.  It should be one of the ``pipe_shader_ir`` enum values.
    450 * ``PIPE_SHADER_CAP_MAX_SAMPLER_VIEWS``: The maximum number of texture
    451   sampler views. Must not be lower than PIPE_SHADER_CAP_MAX_TEXTURE_SAMPLERS.
    452 * ``PIPE_SHADER_CAP_DOUBLES``: Whether double precision floating-point
    453   operations are supported.
    454 * ``PIPE_SHADER_CAP_TGSI_DROUND_SUPPORTED``: Whether double precision rounding
    455   is supported. If it is, DTRUNC/DCEIL/DFLR/DROUND opcodes may be used.
    456 * ``PIPE_SHADER_CAP_TGSI_DFRACEXP_DLDEXP_SUPPORTED``: Whether DFRACEXP and
    457   DLDEXP are supported.
    458 * ``PIPE_SHADER_CAP_TGSI_FMA_SUPPORTED``: Whether FMA and DFMA (doubles only)
    459   are supported.
    460 * ``PIPE_SHADER_CAP_TGSI_ANY_INOUT_DECL_RANGE``: Whether the driver doesn't
    461   ignore tgsi_declaration_range::Last for shader inputs and outputs.
    462 * ``PIPE_SHADER_CAP_MAX_UNROLL_ITERATIONS_HINT``: This is the maximum number
    463   of iterations that loops are allowed to have to be unrolled. It is only
    464   a hint to state trackers. Whether any loops will be unrolled is not
    465   guaranteed.
    466 * ``PIPE_SHADER_CAP_MAX_SHADER_BUFFERS``: Maximum number of memory buffers
    467   (also used to implement atomic counters). Having this be non-0 also
    468   implies support for the ``LOAD``, ``STORE``, and ``ATOM*`` TGSI
    469   opcodes.
    470 * ``PIPE_SHADER_CAP_SUPPORTED_IRS``: Supported representations of the
    471   program.  It should be a mask of ``pipe_shader_ir`` bits.
    472 * ``PIPE_SHADER_CAP_MAX_SHADER_IMAGES``: Maximum number of image units.
    473 * ``PIPE_SHADER_CAP_LOWER_IF_THRESHOLD``: IF and ELSE branches with a lower
    474   cost than this value should be lowered by the state tracker for better
    475   performance. This is a tunable for the GLSL compiler and the behavior is
    476   specific to the compiler.
    477 
    478 
    479 .. _pipe_compute_cap:
    480 
    481 PIPE_COMPUTE_CAP_*
    482 ^^^^^^^^^^^^^^^^^^
    483 
    484 Compute-specific capabilities. They can be queried using
    485 pipe_screen::get_compute_param.
    486 
    487 * ``PIPE_COMPUTE_CAP_IR_TARGET``: A description of the target of the form
    488   ``processor-arch-manufacturer-os`` that will be passed on to the compiler.
    489   This CAP is only relevant for drivers that specify PIPE_SHADER_IR_LLVM
    490   or PIPE_SHADER_IR_NATIVE for their preferred IR.
    491   Value type: null-terminated string. Shader IR type dependent.
    492 * ``PIPE_COMPUTE_CAP_GRID_DIMENSION``: Number of supported dimensions
    493   for grid and block coordinates.  Value type: ``uint64_t``. Shader IR type dependent.
    494 * ``PIPE_COMPUTE_CAP_MAX_GRID_SIZE``: Maximum grid size in block
    495   units.  Value type: ``uint64_t []``.  Shader IR type dependent.
    496 * ``PIPE_COMPUTE_CAP_MAX_BLOCK_SIZE``: Maximum block size in thread
    497   units.  Value type: ``uint64_t []``. Shader IR type dependent.
    498 * ``PIPE_COMPUTE_CAP_MAX_THREADS_PER_BLOCK``: Maximum number of threads that
    499   a single block can contain.  Value type: ``uint64_t``. Shader IR type dependent.
    500   This may be less than the product of the components of MAX_BLOCK_SIZE and is
    501   usually limited by the number of threads that can be resident simultaneously
    502   on a compute unit.
    503 * ``PIPE_COMPUTE_CAP_MAX_GLOBAL_SIZE``: Maximum size of the GLOBAL
    504   resource.  Value type: ``uint64_t``. Shader IR type dependent.
    505 * ``PIPE_COMPUTE_CAP_MAX_LOCAL_SIZE``: Maximum size of the LOCAL
    506   resource.  Value type: ``uint64_t``. Shader IR type dependent.
    507 * ``PIPE_COMPUTE_CAP_MAX_PRIVATE_SIZE``: Maximum size of the PRIVATE
    508   resource.  Value type: ``uint64_t``. Shader IR type dependent.
    509 * ``PIPE_COMPUTE_CAP_MAX_INPUT_SIZE``: Maximum size of the INPUT
    510   resource.  Value type: ``uint64_t``. Shader IR type dependent.
    511 * ``PIPE_COMPUTE_CAP_MAX_MEM_ALLOC_SIZE``: Maximum size of a memory object
    512   allocation in bytes.  Value type: ``uint64_t``.
    513 * ``PIPE_COMPUTE_CAP_MAX_CLOCK_FREQUENCY``: Maximum frequency of the GPU
    514   clock in MHz. Value type: ``uint32_t``
    515 * ``PIPE_COMPUTE_CAP_MAX_COMPUTE_UNITS``: Maximum number of compute units
    516   Value type: ``uint32_t``
    517 * ``PIPE_COMPUTE_CAP_IMAGES_SUPPORTED``: Whether images are supported
    518   non-zero means yes, zero means no. Value type: ``uint32_t``
    519 * ``PIPE_COMPUTE_CAP_SUBGROUP_SIZE``: The size of a basic execution unit in
    520   threads. Also known as wavefront size, warp size or SIMD width.
    521 * ``PIPE_COMPUTE_CAP_ADDRESS_BITS``: The default compute device address space
    522   size specified as an unsigned integer value in bits.
    523 * ``PIPE_COMPUTE_CAP_MAX_VARIABLE_THREADS_PER_BLOCK``: Maximum variable number
    524   of threads that a single block can contain. This is similar to
    525   PIPE_COMPUTE_CAP_MAX_THREADS_PER_BLOCK, except that the variable size is not
    526   known a compile-time but at dispatch-time.
    527 
    528 .. _pipe_bind:
    529 
    530 PIPE_BIND_*
    531 ^^^^^^^^^^^
    532 
    533 These flags indicate how a resource will be used and are specified at resource
    534 creation time. Resources may be used in different roles
    535 during their lifecycle. Bind flags are cumulative and may be combined to create
    536 a resource which can be used for multiple things.
    537 Depending on the pipe driver's memory management and these bind flags,
    538 resources might be created and handled quite differently.
    539 
    540 * ``PIPE_BIND_RENDER_TARGET``: A color buffer or pixel buffer which will be
    541   rendered to.  Any surface/resource attached to pipe_framebuffer_state::cbufs
    542   must have this flag set.
    543 * ``PIPE_BIND_DEPTH_STENCIL``: A depth (Z) buffer and/or stencil buffer. Any
    544   depth/stencil surface/resource attached to pipe_framebuffer_state::zsbuf must
    545   have this flag set.
    546 * ``PIPE_BIND_BLENDABLE``: Used in conjunction with PIPE_BIND_RENDER_TARGET to
    547   query whether a device supports blending for a given format.
    548   If this flag is set, surface creation may fail if blending is not supported
    549   for the specified format. If it is not set, a driver may choose to ignore
    550   blending on surfaces with formats that would require emulation.
    551 * ``PIPE_BIND_DISPLAY_TARGET``: A surface that can be presented to screen. Arguments to
    552   pipe_screen::flush_front_buffer must have this flag set.
    553 * ``PIPE_BIND_SAMPLER_VIEW``: A texture that may be sampled from in a fragment
    554   or vertex shader.
    555 * ``PIPE_BIND_VERTEX_BUFFER``: A vertex buffer.
    556 * ``PIPE_BIND_INDEX_BUFFER``: An vertex index/element buffer.
    557 * ``PIPE_BIND_CONSTANT_BUFFER``: A buffer of shader constants.
    558 * ``PIPE_BIND_STREAM_OUTPUT``: A stream output buffer.
    559 * ``PIPE_BIND_CUSTOM``:
    560 * ``PIPE_BIND_SCANOUT``: A front color buffer or scanout buffer.
    561 * ``PIPE_BIND_SHARED``: A sharable buffer that can be given to another
    562   process.
    563 * ``PIPE_BIND_GLOBAL``: A buffer that can be mapped into the global
    564   address space of a compute program.
    565 * ``PIPE_BIND_SHADER_BUFFER``: A buffer without a format that can be bound
    566   to a shader and can be used with load, store, and atomic instructions.
    567 * ``PIPE_BIND_SHADER_IMAGE``: A buffer or texture with a format that can be
    568   bound to a shader and can be used with load, store, and atomic instructions.
    569 * ``PIPE_BIND_COMPUTE_RESOURCE``: A buffer or texture that can be
    570   bound to the compute program as a shader resource.
    571 * ``PIPE_BIND_COMMAND_ARGS_BUFFER``: A buffer that may be sourced by the
    572   GPU command processor. It can contain, for example, the arguments to
    573   indirect draw calls.
    574 
    575 .. _pipe_usage:
    576 
    577 PIPE_USAGE_*
    578 ^^^^^^^^^^^^
    579 
    580 The PIPE_USAGE enums are hints about the expected usage pattern of a resource.
    581 Note that drivers must always support read and write CPU access at any time
    582 no matter which hint they got.
    583 
    584 * ``PIPE_USAGE_DEFAULT``: Optimized for fast GPU access.
    585 * ``PIPE_USAGE_IMMUTABLE``: Optimized for fast GPU access and the resource is
    586   not expected to be mapped or changed (even by the GPU) after the first upload.
    587 * ``PIPE_USAGE_DYNAMIC``: Expect frequent write-only CPU access. What is
    588   uploaded is expected to be used at least several times by the GPU.
    589 * ``PIPE_USAGE_STREAM``: Expect frequent write-only CPU access. What is
    590   uploaded is expected to be used only once by the GPU.
    591 * ``PIPE_USAGE_STAGING``: Optimized for fast CPU access.
    592 
    593 
    594 Methods
    595 -------
    596 
    597 XXX to-do
    598 
    599 get_name
    600 ^^^^^^^^
    601 
    602 Returns an identifying name for the screen.
    603 
    604 get_vendor
    605 ^^^^^^^^^^
    606 
    607 Returns the screen vendor.
    608 
    609 get_device_vendor
    610 ^^^^^^^^^^^^^^^^^
    611 
    612 Returns the actual vendor of the device driving the screen
    613 (as opposed to the driver vendor).
    614 
    615 .. _get_param:
    616 
    617 get_param
    618 ^^^^^^^^^
    619 
    620 Get an integer/boolean screen parameter.
    621 
    622 **param** is one of the :ref:`PIPE_CAP` names.
    623 
    624 .. _get_paramf:
    625 
    626 get_paramf
    627 ^^^^^^^^^^
    628 
    629 Get a floating-point screen parameter.
    630 
    631 **param** is one of the :ref:`PIPE_CAP` names.
    632 
    633 context_create
    634 ^^^^^^^^^^^^^^
    635 
    636 Create a pipe_context.
    637 
    638 **priv** is private data of the caller, which may be put to various
    639 unspecified uses, typically to do with implementing swapbuffers
    640 and/or front-buffer rendering.
    641 
    642 is_format_supported
    643 ^^^^^^^^^^^^^^^^^^^
    644 
    645 Determine if a resource in the given format can be used in a specific manner.
    646 
    647 **format** the resource format
    648 
    649 **target** one of the PIPE_TEXTURE_x flags
    650 
    651 **sample_count** the number of samples. 0 and 1 mean no multisampling,
    652 the maximum allowed legal value is 32.
    653 
    654 **bindings** is a bitmask of :ref:`PIPE_BIND` flags.
    655 
    656 **geom_flags** is a bitmask of PIPE_TEXTURE_GEOM_x flags.
    657 
    658 Returns TRUE if all usages can be satisfied.
    659 
    660 
    661 can_create_resource
    662 ^^^^^^^^^^^^^^^^^^^
    663 
    664 Check if a resource can actually be created (but don't actually allocate any
    665 memory).  This is used to implement OpenGL's proxy textures.  Typically, a
    666 driver will simply check if the total size of the given resource is less than
    667 some limit.
    668 
    669 For PIPE_TEXTURE_CUBE, the pipe_resource::array_size field should be 6.
    670 
    671 
    672 .. _resource_create:
    673 
    674 resource_create
    675 ^^^^^^^^^^^^^^^
    676 
    677 Create a new resource from a template.
    678 The following fields of the pipe_resource must be specified in the template:
    679 
    680 **target** one of the pipe_texture_target enums.
    681 Note that PIPE_BUFFER and PIPE_TEXTURE_X are not really fundamentally different.
    682 Modern APIs allow using buffers as shader resources.
    683 
    684 **format** one of the pipe_format enums.
    685 
    686 **width0** the width of the base mip level of the texture or size of the buffer.
    687 
    688 **height0** the height of the base mip level of the texture
    689 (1 for 1D or 1D array textures).
    690 
    691 **depth0** the depth of the base mip level of the texture
    692 (1 for everything else).
    693 
    694 **array_size** the array size for 1D and 2D array textures.
    695 For cube maps this must be 6, for other textures 1.
    696 
    697 **last_level** the last mip map level present.
    698 
    699 **nr_samples** the nr of msaa samples. 0 (or 1) specifies a resource
    700 which isn't multisampled.
    701 
    702 **usage** one of the PIPE_USAGE flags.
    703 
    704 **bind** bitmask of the PIPE_BIND flags.
    705 
    706 **flags** bitmask of PIPE_RESOURCE_FLAG flags.
    707 
    708 
    709 
    710 resource_destroy
    711 ^^^^^^^^^^^^^^^^
    712 
    713 Destroy a resource. A resource is destroyed if it has no more references.
    714 
    715 
    716 
    717 get_timestamp
    718 ^^^^^^^^^^^^^
    719 
    720 Query a timestamp in nanoseconds. The returned value should match
    721 PIPE_QUERY_TIMESTAMP. This function returns immediately and doesn't
    722 wait for rendering to complete (which cannot be achieved with queries).
    723 
    724 
    725 
    726 get_driver_query_info
    727 ^^^^^^^^^^^^^^^^^^^^^
    728 
    729 Return a driver-specific query. If the **info** parameter is NULL,
    730 the number of available queries is returned.  Otherwise, the driver
    731 query at the specified **index** is returned in **info**.
    732 The function returns non-zero on success.
    733 The driver-specific query is described with the pipe_driver_query_info
    734 structure.
    735 
    736 get_driver_query_group_info
    737 ^^^^^^^^^^^^^^^^^^^^^^^^^^^
    738 
    739 Return a driver-specific query group. If the **info** parameter is NULL,
    740 the number of available groups is returned.  Otherwise, the driver
    741 query group at the specified **index** is returned in **info**.
    742 The function returns non-zero on success.
    743 The driver-specific query group is described with the
    744 pipe_driver_query_group_info structure.
    745 
    746 
    747 Thread safety
    748 -------------
    749 
    750 Screen methods are required to be thread safe. While gallium rendering
    751 contexts are not required to be thread safe, it is required to be safe to use
    752 different contexts created with the same screen in different threads without
    753 locks. It is also required to be safe using screen methods in a thread, while
    754 using one of its contexts in another (without locks).
    755