src/gallium/docs/source/screen.rst

   1 Screen
   2 ======
   3
   4 A screen is an object representing the context-independent part of a device.
   5
   6 Useful Flags
   7 ------------
   8
   9 .. _pipe_cap:
  10
  11 PIPE_CAP
  12 ^^^^^^^^
  13
  14 Pipe capabilities help expose hardware functionality not explicitly required
  15 by Gallium. For floating-point values, use :ref:`get_paramf`, and for boolean
  16 or integer values, use :ref:`get_param`.
  17
  18 The integer capabilities:
  19
  20 * ``MAX_TEXTURE_IMAGE_UNITS``: The maximum number of samplers available.
  21 * ``NPOT_TEXTURES``: Whether :term:`NPOT` textures may have repeat modes,
  22   normalized coordinates, and mipmaps.
  23 * ``TWO_SIDED_STENCIL``: Whether the stencil test can also affect back-facing
  24   polygons.
  25 * ``GLSL``: Deprecated.
  26 * ``DUAL_SOURCE_BLEND``: Whether dual-source blend factors are supported. See
  27   :ref:`Blend` for more information.
  28 * ``ANISOTROPIC_FILTER``: Whether textures can be filtered anisotropically.
  29 * ``POINT_SPRITE``: Whether point sprites are available.
  30 * ``MAX_RENDER_TARGETS``: The maximum number of render targets that may be
  31   bound.
  32 * ``OCCLUSION_QUERY``: Whether occlusion queries are available.
  33 * ``TEXTURE_SHADOW_MAP``: XXX
  34 * ``MAX_TEXTURE_2D_LEVELS``: The maximum number of mipmap levels available
  35   for a 2D texture.
  36 * ``MAX_TEXTURE_3D_LEVELS``: The maximum number of mipmap levels available
  37   for a 3D texture.
  38 * ``MAX_TEXTURE_CUBE_LEVELS``: The maximum number of mipmap levels available
  39   for a cubemap.
  40 * ``TEXTURE_MIRROR_CLAMP``: Whether mirrored texture coordinates with clamp
  41   are supported.
  42 * ``TEXTURE_MIRROR_REPEAT``: Whether mirrored repeating texture coordinates
  43   are supported.
  44 * ``MAX_VERTEX_TEXTURE_UNITS``: The maximum number of samplers addressable
  45   inside the vertex shader. If this is 0, then the vertex shader cannot
  46   sample textures.
  47 * ``TGSI_CONT_SUPPORTED``: Whether the TGSI CONT opcode is supported.
  48 * ``BLEND_EQUATION_SEPARATE``: Whether alpha blend equations may be different
  49   from color blend equations, in :ref:`Blend` state.
  50 * ``SM3``: Whether the vertex shader and fragment shader support equivalent
  51   opcodes to the Shader Model 3 specification. XXX oh god this is horrible
  52 * ``MAX_PREDICATE_REGISTERS``: XXX
  53 * ``MAX_COMBINED_SAMPLERS``: The total number of samplers accessible from
  54   the vertex and fragment shader, inclusive.
  55 * ``MAX_CONST_BUFFERS``: Maximum number of constant buffers that can be bound
  56   to any shader stage using ``set_constant_buffer``. If 0 or 1, the pipe will
  57   only permit binding one constant buffer per shader, and the shaders will
  58   not permit two-dimensional access to constants.
  59 * ``MAX_CONST_BUFFER_SIZE``: Maximum byte size of a single constant buffer.
  60 * ``INDEP_BLEND_ENABLE``: Whether per-rendertarget blend enabling and channel
  61   masks are supported. If 0, then the first rendertarget's blend mask is
  62   replicated across all MRTs.
  63 * ``INDEP_BLEND_FUNC``: Whether per-rendertarget blend functions are
  64   available. If 0, then the first rendertarget's blend functions affect all
  65   MRTs.
  66 * ``PIPE_CAP_TGSI_FS_COORD_ORIGIN_UPPER_LEFT``: Whether the TGSI property
  67   FS_COORD_ORIGIN with value UPPER_LEFT is supported.
  68 * ``PIPE_CAP_TGSI_FS_COORD_ORIGIN_LOWER_LEFT``: Whether the TGSI property
  69   FS_COORD_ORIGIN with value LOWER_LEFT is supported.
  70 * ``PIPE_CAP_TGSI_FS_COORD_PIXEL_CENTER_HALF_INTEGER``: Whether the TGSI
  71   property FS_COORD_PIXEL_CENTER with value HALF_INTEGER is supported.
  72 * ``PIPE_CAP_TGSI_FS_COORD_PIXEL_CENTER_INTEGER``: Whether the TGSI
  73   property FS_COORD_PIXEL_CENTER with value INTEGER is supported.
  74
  75 The floating-point capabilities:
  76
  77 * ``MAX_LINE_WIDTH``: The maximum width of a regular line.
  78 * ``MAX_LINE_WIDTH_AA``: The maximum width of a smoothed line.
  79 * ``MAX_POINT_WIDTH``: The maximum width and height of a point.
  80 * ``MAX_POINT_WIDTH_AA``: The maximum width and height of a smoothed point.
  81 * ``MAX_TEXTURE_ANISOTROPY``: The maximum level of anisotropy that can be
  82   applied to anisotropically filtered textures.
  83 * ``MAX_TEXTURE_LOD_BIAS``: The maximum :term:`LOD` bias that may be applied
  84   to filtered textures.
  85 * ``GUARD_BAND_LEFT``, ``GUARD_BAND_TOP``, ``GUARD_BAND_RIGHT``,
  86   ``GUARD_BAND_BOTTOM``: XXX
  87
  88 XXX Is there a better home for this? vvv
  89
  90 If 0 is returned, the driver is not aware of multiple constant buffers,
  91 supports binding of only one constant buffer, and does not support
  92 two-dimensional CONST register file access in TGSI shaders.
  93
  94 If a value greater than 0 is returned, the driver can have multiple
  95 constant buffers bound to shader stages. The CONST register file can
  96 be accessed with two-dimensional indices, like in the example below.
  97
  98 DCL CONST[0][0..7]       # declare first 8 vectors of constbuf 0
  99 DCL CONST[3][0]          # declare first vector of constbuf 3
 100 MOV OUT[0], CONST[0][3]  # copy vector 3 of constbuf 0
 101
 102 For backwards compatibility, one-dimensional access to CONST register
 103 file is still supported. In that case, the constbuf index is assumed
 104 to be 0.
 105
 106 .. _pipe_buffer_usage:
 107
 108 PIPE_BUFFER_USAGE
 109 ^^^^^^^^^^^^^^^^^
 110
 111 These flags control buffer creation. Buffers may only have one role, so
 112 care should be taken to not allocate a buffer with the wrong usage.
 113
 114 * ``PIXEL``: This is the flag to use for all textures.
 115 * ``VERTEX``: A vertex buffer.
 116 * ``INDEX``: An element buffer.
 117 * ``CONSTANT``: A buffer of shader constants.
 118
 119 Buffers are inevitably abstracting the pipe's underlying memory management,
 120 so many of their usage flags can be used to direct the way the buffer is
 121 handled.
 122
 123 * ``CPU_READ``, ``CPU_WRITE``: Whether the user will map and, in the case of
 124   the latter, write to, the buffer. The convenience flag ``CPU_READ_WRITE`` is
 125   available to signify a read/write buffer.
 126 * ``GPU_READ``, ``GPU_WRITE``: Whether the driver will internally need to
 127   read from or write to the buffer. The latter will only happen if the buffer
 128   is made into a render target.
 129 * ``DISCARD``: When set on a map, the contents of the map will be discarded
 130   beforehand. Cannot be used with ``CPU_READ``.
 131 * ``DONTBLOCK``: When set on a map, the map will fail if the buffer cannot be
 132   mapped immediately.
 133 * ``UNSYNCHRONIZED``: When set on a map, any outstanding operations on the
 134   buffer will be ignored. The interaction of any writes to the map and any
 135   operations pending with the buffer are undefined. Cannot be used with
 136   ``CPU_READ``.
 137 * ``FLUSH_EXPLICIT``: When set on a map, written ranges of the map require
 138   explicit flushes using :ref:`buffer_flush_mapped_range`. Requires
 139   ``CPU_WRITE``.
 140
 141 .. _pipe_texture_usage:
 142
 143 PIPE_TEXTURE_USAGE
 144 ^^^^^^^^^^^^^^^^^^
 145
 146 These flags determine the possible roles a texture may be used for during its
 147 lifetime. Texture usage flags are cumulative and may be combined to create a
 148 texture that can be used as multiple things.
 149
 150 * ``RENDER_TARGET``: A colorbuffer or pixelbuffer.
 151 * ``DISPLAY_TARGET``: A sharable buffer that can be given to another process.
 152 * ``PRIMARY``: A frontbuffer or scanout buffer.
 153 * ``DEPTH_STENCIL``: A depthbuffer, stencilbuffer, or Z buffer. Gallium does
 154   not explicitly provide for stencil-only buffers, so any stencilbuffer
 155   validated here is implicitly also a depthbuffer.
 156 * ``SAMPLER``: A texture that may be sampled from in a fragment or vertex
 157   shader.
 158 * ``DYNAMIC``: A texture that will be mapped frequently.
 159
 160 Methods
 161 -------
 162
 163 XXX moar; got bored
 164
 165 get_name
 166 ^^^^^^^^
 167
 168 Returns an identifying name for the screen.
 169
 170 get_vendor
 171 ^^^^^^^^^^
 172
 173 Returns the screen vendor.
 174
 175 .. _get_param:
 176
 177 get_param
 178 ^^^^^^^^^
 179
 180 Get an integer/boolean screen parameter.
 181
 182 **param** is one of the :ref:`PIPE_CAP` names.
 183
 184 .. _get_paramf:
 185
 186 get_paramf
 187 ^^^^^^^^^^
 188
 189 Get a floating-point screen parameter.
 190
 191 **param** is one of the :ref:`PIPE_CAP` names.
 192
 193 context_create
 194 ^^^^^^^^^^^^^^
 195
 196 Create a pipe_context.
 197
 198 **priv** is private data of the caller, which may be put to various
 199 unspecified uses, typically to do with implementing swapbuffers
 200 and/or front-buffer rendering.
 201
 202 is_format_supported
 203 ^^^^^^^^^^^^^^^^^^^
 204
 205 See if a format can be used in a specific manner.
 206
 207 **usage** is a bitmask of :ref:`PIPE_TEXTURE_USAGE` flags.
 208
 209 Returns TRUE if all usages can be satisfied.
 210
 211 .. note::
 212
 213    ``PIPE_TEXTURE_USAGE_DYNAMIC`` is not a valid usage.
 214
 215 .. _texture_create:
 216
 217 texture_create
 218 ^^^^^^^^^^^^^^
 219
 220 Given a template of texture setup, create a buffer and texture.
 221
 222 texture_blanket
 223 ^^^^^^^^^^^^^^^
 224
 225 Like :ref:`texture_create`, but use a supplied buffer instead of creating a
 226 new one.
 227
 228 texture_destroy
 229 ^^^^^^^^^^^^^^^
 230
 231 Destroy a texture. The buffer backing the texture is destroyed if it has no
 232 more references.
 233
 234 buffer_map
 235 ^^^^^^^^^^
 236
 237 Map a buffer into memory.
 238
 239 **usage** is a bitmask of :ref:`PIPE_BUFFER_USAGE` flags.
 240
 241 Returns a pointer to the map, or NULL if the mapping failed.
 242
 243 buffer_map_range
 244 ^^^^^^^^^^^^^^^^
 245
 246 Map a range of a buffer into memory.
 247
 248 The returned map is always relative to the beginning of the buffer, not the
 249 beginning of the mapped range.
 250
 251 .. _buffer_flush_mapped_range:
 252
 253 buffer_flush_mapped_range
 254 ^^^^^^^^^^^^^^^^^^^^^^^^^
 255
 256 Flush a range of mapped memory into a buffer.
 257
 258 The buffer must have been mapped with ``PIPE_BUFFER_USAGE_FLUSH_EXPLICIT``.
 259
 260 **usage** is a bitmask of :ref:`PIPE_BUFFER_USAGE` flags.
 261
 262 buffer_unmap
 263 ^^^^^^^^^^^^
 264
 265 Unmap a buffer from memory.
 266
 267 Any pointers into the map should be considered invalid and discarded.