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 * ``PIPE_CAP_TGSI_FS_COORD_ORIGIN_UPPER_LEFT``: Whether the TGSI property
  61   FS_COORD_ORIGIN with value UPPER_LEFT is supported
  62 * ``PIPE_CAP_TGSI_FS_COORD_ORIGIN_LOWER_LEFT``: Whether the TGSI property
  63   FS_COORD_ORIGIN with value LOWER_LEFT is supported
  64 * ``PIPE_CAP_TGSI_FS_COORD_PIXEL_CENTER_HALF_INTEGER``: Whether the TGSI
  65   property FS_COORD_PIXEL_CENTER with value HALF_INTEGER is supported
  66 * ``PIPE_CAP_TGSI_FS_COORD_PIXEL_CENTER_INTEGER``: Whether the TGSI
  67   property FS_COORD_PIXEL_CENTER with value INTEGER is supported
  68
  69 The floating-point capabilities:
  70
  71 * ``MAX_LINE_WIDTH``: The maximum width of a regular line.
  72 * ``MAX_LINE_WIDTH_AA``: The maximum width of a smoothed line.
  73 * ``MAX_POINT_WIDTH``: The maximum width and height of a point.
  74 * ``MAX_POINT_WIDTH_AA``: The maximum width and height of a smoothed point.
  75 * ``GUARD_BAND_LEFT``, ``GUARD_BAND_TOP``, ``GUARD_BAND_RIGHT``,
  76   ``GUARD_BAND_BOTTOM``: XXX
  77
  78 XXX Is there a better home for this? vvv
  79
  80 If 0 is returned, the driver is not aware of multiple constant buffers,
  81 supports binding of only one constant buffer, and does not support
  82 two-dimensional CONST register file access in TGSI shaders.
  83
  84 If a value greater than 0 is returned, the driver can have multiple
  85 constant buffers bound to shader stages. The CONST register file can
  86 be accessed with two-dimensional indices, like in the example below.
  87
  88 DCL CONST[0][0..7]       # declare first 8 vectors of constbuf 0
  89 DCL CONST[3][0]          # declare first vector of constbuf 3
  90 MOV OUT[0], CONST[0][3]  # copy vector 3 of constbuf 0
  91
  92 For backwards compatibility, one-dimensional access to CONST register
  93 file is still supported. In that case, the constbuf index is assumed
  94 to be 0.
  95
  96 .. _pipe_buffer_usage:
  97
  98 PIPE_BUFFER_USAGE
  99 ^^^^^^^^^^^^^^^^^
 100
 101 These flags control buffer creation. Buffers may only have one role, so
 102 care should be taken to not allocate a buffer with the wrong usage.
 103
 104 * ``PIXEL``: This is the flag to use for all textures.
 105 * ``VERTEX``: A vertex buffer.
 106 * ``INDEX``: An element buffer.
 107 * ``CONSTANT``: A buffer of shader constants.
 108
 109 Buffers are inevitably abstracting the pipe's underlying memory management,
 110 so many of their usage flags can be used to direct the way the buffer is
 111 handled.
 112
 113 * ``CPU_READ``, ``CPU_WRITE``: Whether the user will map and, in the case of
 114   the latter, write to, the buffer. The convenience flag ``CPU_READ_WRITE`` is
 115   available to signify a read/write buffer.
 116 * ``GPU_READ``, ``GPU_WRITE``: Whether the driver will internally need to
 117   read from or write to the buffer. The latter will only happen if the buffer
 118   is made into a render target.
 119 * ``DISCARD``: When set on a map, the contents of the map will be discarded
 120   beforehand. Cannot be used with ``CPU_READ``.
 121 * ``DONTBLOCK``: When set on a map, the map will fail if the buffer cannot be
 122   mapped immediately.
 123 * ``UNSYNCHRONIZED``: When set on a map, any outstanding operations on the
 124   buffer will be ignored. The interaction of any writes to the map and any
 125   operations pending with the buffer are undefined. Cannot be used with
 126   ``CPU_READ``.
 127 * ``FLUSH_EXPLICIT``: When set on a map, written ranges of the map require
 128   explicit flushes using :ref:`buffer_flush_mapped_range`. Requires
 129   ``CPU_WRITE``.
 130
 131 .. _pipe_texture_usage:
 132
 133 PIPE_TEXTURE_USAGE
 134 ^^^^^^^^^^^^^^^^^^
 135
 136 These flags determine the possible roles a texture may be used for during its
 137 lifetime. Texture usage flags are cumulative and may be combined to create a
 138 texture that can be used as multiple things.
 139
 140 * ``RENDER_TARGET``: A colorbuffer or pixelbuffer.
 141 * ``DISPLAY_TARGET``: A sharable buffer that can be given to another process.
 142 * ``PRIMARY``: A frontbuffer or scanout buffer.
 143 * ``DEPTH_STENCIL``: A depthbuffer, stencilbuffer, or Z buffer. Gallium does
 144   not explicitly provide for stencil-only buffers, so any stencilbuffer
 145   validated here is implicitly also a depthbuffer.
 146 * ``SAMPLER``: A texture that may be sampled from in a fragment or vertex
 147   shader.
 148 * ``DYNAMIC``: A texture that will be mapped frequently.
 149
 150 Methods
 151 -------
 152
 153 XXX moar; got bored
 154
 155 get_name
 156 ^^^^^^^^
 157
 158 Returns an identifying name for the screen.
 159
 160 get_vendor
 161 ^^^^^^^^^^
 162
 163 Returns the screen vendor.
 164
 165 .. _get_param:
 166
 167 get_param
 168 ^^^^^^^^^
 169
 170 Get an integer/boolean screen parameter.
 171
 172 **param** is one of the :ref:`PIPE_CAP` names.
 173
 174 .. _get_paramf:
 175
 176 get_paramf
 177 ^^^^^^^^^^
 178
 179 Get a floating-point screen parameter.
 180
 181 **param** is one of the :ref:`PIPE_CAP` names.
 182
 183 is_format_supported
 184 ^^^^^^^^^^^^^^^^^^^
 185
 186 See if a format can be used in a specific manner.
 187
 188 **usage** is a bitmask of :ref:`PIPE_TEXTURE_USAGE` flags.
 189
 190 Returns TRUE if all usages can be satisfied.
 191
 192 .. note::
 193
 194    ``PIPE_TEXTURE_USAGE_DYNAMIC`` is not a valid usage.
 195
 196 .. _texture_create:
 197
 198 texture_create
 199 ^^^^^^^^^^^^^^
 200
 201 Given a template of texture setup, create a buffer and texture.
 202
 203 texture_blanket
 204 ^^^^^^^^^^^^^^^
 205
 206 Like :ref:`texture_create`, but use a supplied buffer instead of creating a
 207 new one.
 208
 209 texture_destroy
 210 ^^^^^^^^^^^^^^^
 211
 212 Destroy a texture. The buffer backing the texture is destroyed if it has no
 213 more references.
 214
 215 buffer_map
 216 ^^^^^^^^^^
 217
 218 Map a buffer into memory.
 219
 220 **usage** is a bitmask of :ref:`PIPE_TEXTURE_USAGE` flags.
 221
 222 Returns a pointer to the map, or NULL if the mapping failed.
 223
 224 buffer_map_range
 225 ^^^^^^^^^^^^^^^^
 226
 227 Map a range of a buffer into memory.
 228
 229 The returned map is always relative to the beginning of the buffer, not the
 230 beginning of the mapped range.
 231
 232 .. _buffer_flush_mapped_range:
 233
 234 buffer_flush_mapped_range
 235 ^^^^^^^^^^^^^^^^^^^^^^^^^
 236
 237 Flush a range of mapped memory into a buffer.
 238
 239 The buffer must have been mapped with ``PIPE_BUFFER_USAGE_FLUSH_EXPLICIT``.
 240
 241 **usage** is a bitmask of :ref:`PIPE_TEXTURE_USAGE` flags.
 242
 243 buffer_unmap
 244 ^^^^^^^^^^^^
 245
 246 Unmap a buffer from memory.
 247
 248 Any pointers into the map should be considered invalid and discarded.