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Diffstat (limited to 'src/gallium/docs/source/tgsi.rst')
| -rw-r--r-- | src/gallium/docs/source/tgsi.rst | 195 |
1 files changed, 123 insertions, 72 deletions
diff --git a/src/gallium/docs/source/tgsi.rst b/src/gallium/docs/source/tgsi.rst index e2c8602da02..9e02d43ab74 100644 --- a/src/gallium/docs/source/tgsi.rst +++ b/src/gallium/docs/source/tgsi.rst @@ -26,9 +26,11 @@ each of the components of *dst*. When this happens, the result is said to be Instruction Set --------------- -From GL_NV_vertex_program +Core ISA ^^^^^^^^^^^^^^^^^^^^^^^^^ +These opcodes are guaranteed to be available regardless of the driver being +used. .. opcode:: ARL - Address Register Load @@ -287,7 +289,7 @@ This instruction replicates its result. dst.w = src0.x \times src1.x + src0.y \times src1.y + src2.x -.. opcode:: FRAC - Fraction +.. opcode:: FRC - Fraction .. math:: @@ -637,10 +639,6 @@ This instruction replicates its result. Considered for removal. -From GL_NV_vertex_program2 -^^^^^^^^^^^^^^^^^^^^^^^^^^ - - .. opcode:: ARA - Address Register Add TBD @@ -680,8 +678,6 @@ From GL_NV_vertex_program2 pc = pop() - Potential restrictions: - * Only occurs at end of function. .. opcode:: SSG - Set Sign @@ -728,7 +724,7 @@ From GL_NV_vertex_program2 dst.z = 0 - dst.y = 1 + dst.w = 1 .. opcode:: TXB - Texture Lookup With Bias @@ -827,11 +823,14 @@ This instruction replicates its result. Considered for removal. -From GL_NV_gpu_program4 +Compute ISA ^^^^^^^^^^^^^^^^^^^^^^^^ +These opcodes are primarily provided for special-use computational shaders. Support for these opcodes indicated by a special pipe capability bit (TBD). +XXX so let's discuss it, yeah? + .. opcode:: CEIL - Ceiling .. math:: @@ -989,10 +988,17 @@ Support for these opcodes indicated by a special pipe capability bit (TBD). TBD +.. note:: + + Support for CONT is determined by a special capability bit, + ``TGSI_CONT_SUPPORTED``. See :ref:`Screen` for more information. -From GL_NV_geometry_program4 + +Geometry ISA ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +These opcodes are only supported in geometry shaders; they have no meaning +in any other type of shader. .. opcode:: EMIT - Emit @@ -1004,9 +1010,11 @@ From GL_NV_geometry_program4 TBD -From GLSL +GLSL ISA ^^^^^^^^^^ +These opcodes are part of :term:`GLSL`'s opcode set. Support for these +opcodes is determined by a special capability bit, ``GLSL``. .. opcode:: BGNLOOP - Begin a Loop @@ -1045,6 +1053,7 @@ This instruction replicates its result. ps_2_x ^^^^^^^^^^^^ +XXX wait what .. opcode:: CALLNZ - Subroutine Call If Not Zero @@ -1062,10 +1071,15 @@ ps_2_x .. _doubleopcodes: -Double Opcodes +Double ISA ^^^^^^^^^^^^^^^ -.. opcode:: DADD - Add Double +The double-precision opcodes reinterpret four-component vectors into +two-component vectors with doubled precision in each component. + +Support for these opcodes is XXX undecided. :T + +.. opcode:: DADD - Add .. math:: @@ -1074,7 +1088,7 @@ Double Opcodes dst.zw = src0.zw + src1.zw -.. opcode:: DDIV - Divide Double +.. opcode:: DDIV - Divide .. math:: @@ -1082,7 +1096,7 @@ Double Opcodes dst.zw = src0.zw / src1.zw -.. opcode:: DSEQ - Set Double on Equal +.. opcode:: DSEQ - Set on Equal .. math:: @@ -1090,7 +1104,7 @@ Double Opcodes dst.zw = src0.zw == src1.zw ? 1.0F : 0.0F -.. opcode:: DSLT - Set Double on Less than +.. opcode:: DSLT - Set on Less than .. math:: @@ -1098,7 +1112,7 @@ Double Opcodes dst.zw = src0.zw < src1.zw ? 1.0F : 0.0F -.. opcode:: DFRAC - Double Fraction +.. opcode:: DFRAC - Fraction .. math:: @@ -1107,23 +1121,33 @@ Double Opcodes dst.zw = src.zw - \lfloor src.zw\rfloor -.. opcode:: DFRACEXP - Convert Double Number to Fractional and Integral Components +.. opcode:: DFRACEXP - Convert Number to Fractional and Integral Components + +Like the ``frexp()`` routine in many math libraries, this opcode stores the +exponent of its source to ``dst0``, and the significand to ``dst1``, such that +:math:`dst1 \times 2^{dst0} = src` . .. math:: - dst0.xy = frexp(src.xy, dst1.xy) + dst0.xy = exp(src.xy) + + dst1.xy = frac(src.xy) + + dst0.zw = exp(src.zw) - dst0.zw = frexp(src.zw, dst1.zw) + dst1.zw = frac(src.zw) -.. opcode:: DLDEXP - Multiple Double Number by Integral Power of 2 +.. opcode:: DLDEXP - Multiply Number by Integral Power of 2 + +This opcode is the inverse of :opcode:`DFRACEXP`. .. math:: - dst.xy = ldexp(src0.xy, src1.xy) + dst.xy = src0.xy \times 2^{src1.xy} - dst.zw = ldexp(src0.zw, src1.zw) + dst.zw = src0.zw \times 2^{src1.zw} -.. opcode:: DMIN - Minimum Double +.. opcode:: DMIN - Minimum .. math:: @@ -1131,7 +1155,7 @@ Double Opcodes dst.zw = min(src0.zw, src1.zw) -.. opcode:: DMAX - Maximum Double +.. opcode:: DMAX - Maximum .. math:: @@ -1139,7 +1163,7 @@ Double Opcodes dst.zw = max(src0.zw, src1.zw) -.. opcode:: DMUL - Multiply Double +.. opcode:: DMUL - Multiply .. math:: @@ -1148,7 +1172,7 @@ Double Opcodes dst.zw = src0.zw \times src1.zw -.. opcode:: DMAD - Multiply And Add Doubles +.. opcode:: DMAD - Multiply And Add .. math:: @@ -1157,7 +1181,7 @@ Double Opcodes dst.zw = src0.zw \times src1.zw + src2.zw -.. opcode:: DRCP - Reciprocal Double +.. opcode:: DRCP - Reciprocal .. math:: @@ -1165,7 +1189,7 @@ Double Opcodes dst.zw = \frac{1}{src.zw} -.. opcode:: DSQRT - Square root double +.. opcode:: DSQRT - Square Root .. math:: @@ -1260,6 +1284,8 @@ wrapping rules. Declaration Semantic ^^^^^^^^^^^^^^^^^^^^^^^^ + Vertex and fragment shader input and output registers may be labeled + with semantic information consisting of a name and index. Follows Declaration token if Semantic bit is set. @@ -1280,90 +1306,115 @@ Declaration Semantic TGSI_SEMANTIC_POSITION """""""""""""""""""""" -Position, sometimes known as HPOS or WPOS for historical reasons, is the -location of the vertex in space, in ``(x, y, z, w)`` format. ``x``, ``y``, and ``z`` -are the Cartesian coordinates, and ``w`` is the homogenous coordinate and used -for the perspective divide, if enabled. +For vertex shaders, TGSI_SEMANTIC_POSITION indicates the vertex shader +output register which contains the homogeneous vertex position in the clip +space coordinate system. After clipping, the X, Y and Z components of the +vertex will be divided by the W value to get normalized device coordinates. -As a vertex shader output, position should be scaled to the viewport. When -used in fragment shaders, position will be in window coordinates. The convention -used depends on the FS_COORD_ORIGIN and FS_COORD_PIXEL_CENTER properties. +For fragment shaders, TGSI_SEMANTIC_POSITION is used to indicate that +fragment shader input contains the fragment's window position. The X +component starts at zero and always increases from left to right. +The Y component starts at zero and always increases but Y=0 may either +indicate the top of the window or the bottom depending on the fragment +coordinate origin convention (see TGSI_PROPERTY_FS_COORD_ORIGIN). +The Z coordinate ranges from 0 to 1 to represent depth from the front +to the back of the Z buffer. The W component contains the reciprocol +of the interpolated vertex position W component. -XXX additionally, is there a way to configure the perspective divide? it's -accelerated on most chipsets AFAIK... +Fragment shaders may also declare an output register with +TGSI_SEMANTIC_POSITION. Only the Z component is writable. This allows +the fragment shader to change the fragment's Z position. -Position, if not specified, usually defaults to ``(0, 0, 0, 1)``, and can -be partially specified as ``(x, y, 0, 1)`` or ``(x, y, z, 1)``. -XXX usually? can we solidify that? TGSI_SEMANTIC_COLOR """"""""""""""""""" -Colors are used to, well, color the primitives. Colors are always in -``(r, g, b, a)`` format. +For vertex shader outputs or fragment shader inputs/outputs, this +label indicates that the resister contains an R,G,B,A color. + +Several shader inputs/outputs may contain colors so the semantic index +is used to distinguish them. For example, color[0] may be the diffuse +color while color[1] may be the specular color. + +This label is needed so that the flat/smooth shading can be applied +to the right interpolants during rasterization. + -If alpha is not specified, it defaults to 1. TGSI_SEMANTIC_BCOLOR """""""""""""""""""" Back-facing colors are only used for back-facing polygons, and are only valid in vertex shader outputs. After rasterization, all polygons are front-facing -and COLOR and BCOLOR end up occupying the same slots in the fragment, so -all BCOLORs effectively become regular COLORs in the fragment shader. +and COLOR and BCOLOR end up occupying the same slots in the fragment shader, +so all BCOLORs effectively become regular COLORs in the fragment shader. + TGSI_SEMANTIC_FOG """"""""""""""""" -The fog coordinate historically has been used to replace the depth coordinate -for generation of fog in dedicated fog blocks. Gallium, however, does not use -dedicated fog acceleration, placing it entirely in the fragment shader -instead. +Vertex shader inputs and outputs and fragment shader inputs may be +labeled with TGSI_SEMANTIC_FOG to indicate that the register contains +a fog coordinate in the form (F, 0, 0, 1). Typically, the fragment +shader will use the fog coordinate to compute a fog blend factor which +is used to blend the normal fragment color with a constant fog color. + +Only the first component matters when writing from the vertex shader; +the driver will ensure that the coordinate is in this format when used +as a fragment shader input. -The fog coordinate should be written in ``(f, 0, 0, 1)`` format. Only the first -component matters when writing from the vertex shader; the driver will ensure -that the coordinate is in this format when used as a fragment shader input. TGSI_SEMANTIC_PSIZE """"""""""""""""""" -PSIZE, or point size, is used to specify point sizes per-vertex. It should -be in ``(s, 0, 0, 1)`` format, where ``s`` is the (possibly clamped) point size. -Only the first component matters when writing from the vertex shader. +Vertex shader input and output registers may be labeled with +TGIS_SEMANTIC_PSIZE to indicate that the register contains a point size +in the form (S, 0, 0, 1). The point size controls the width or diameter +of points for rasterization. This label cannot be used in fragment +shaders. When using this semantic, be sure to set the appropriate state in the :ref:`rasterizer` first. + TGSI_SEMANTIC_GENERIC """"""""""""""""""""" -Generic semantics are nearly always used for texture coordinate attributes, -in ``(s, t, r, q)`` format. ``t`` and ``r`` may be unused for certain kinds -of lookups, and ``q`` is the level-of-detail bias for biased sampling. +All vertex/fragment shader inputs/outputs not labeled with any other +semantic label can be considered to be generic attributes. Typical +uses of generic inputs/outputs are texcoords and user-defined values. -These attributes are called "generic" because they may be used for anything -else, including parameters, texture generation information, or anything that -can be stored inside a four-component vector. TGSI_SEMANTIC_NORMAL """""""""""""""""""" -Vertex normal; could be used to implement per-pixel lighting for legacy APIs -that allow mixing fixed-function and programmable stages. +Indicates that a vertex shader input is a normal vector. This is +typically only used for legacy graphics APIs. + TGSI_SEMANTIC_FACE """""""""""""""""" -FACE is the facing bit, to store the facing information for the fragment -shader. ``(f, 0, 0, 1)`` is the format. The first component will be positive -when the fragment is front-facing, and negative when the component is -back-facing. +This label applies to fragment shader inputs only and indicates that +the register contains front/back-face information of the form (F, 0, +0, 1). The first component will be positive when the fragment belongs +to a front-facing polygon, and negative when the fragment belongs to a +back-facing polygon. + TGSI_SEMANTIC_EDGEFLAG """""""""""""""""""""" -XXX no clue +For vertex shaders, this sematic label indicates that an input or +output is a boolean edge flag. The register layout is [F, x, x, x] +where F is 0.0 or 1.0 and x = don't care. Normally, the vertex shader +simply copies the edge flag input to the edgeflag output. + +Edge flags are used to control which lines or points are actually +drawn when the polygon mode converts triangles/quads/polygons into +points or lines. + Properties @@ -1420,9 +1471,9 @@ well. +--------------------+--------------+--------------------+--------------+ | Texture Components | Gallium | OpenGL | Direct3D 9 | +====================+==============+====================+==============+ -| R | XXX TBD | (r, 0, 0, 1) | (r, 1, 1, 1) | +| R | (r, 0, 0, 1) | (r, 0, 0, 1) | (r, 1, 1, 1) | +--------------------+--------------+--------------------+--------------+ -| RG | XXX TBD | (r, g, 0, 1) | (r, g, 1, 1) | +| RG | (r, g, 0, 1) | (r, g, 0, 1) | (r, g, 1, 1) | +--------------------+--------------+--------------------+--------------+ | RGB | (r, g, b, 1) | (r, g, b, 1) | (r, g, b, 1) | +--------------------+--------------+--------------------+--------------+ |