You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
366 lines
12 KiB
366 lines
12 KiB
.. _rasterizer:
|
|
|
|
Rasterizer
|
|
==========
|
|
|
|
The rasterizer state controls the rendering of points, lines and triangles.
|
|
Attributes include polygon culling state, line width, line stipple,
|
|
multisample state, scissoring and flat/smooth shading.
|
|
|
|
Linkage
|
|
|
|
clamp_vertex_color
|
|
^^^^^^^^^^^^^^^^^^
|
|
|
|
If set, TGSI_SEMANTIC_COLOR registers are clamped to the [0, 1] range after
|
|
the execution of the vertex shader, before being passed to the geometry
|
|
shader or fragment shader.
|
|
|
|
OpenGL: glClampColor(GL_CLAMP_VERTEX_COLOR) in GL 3.0 or GL_ARB_color_buffer_float
|
|
|
|
D3D11: seems always disabled
|
|
|
|
Note the PIPE_CAP_VERTEX_COLOR_CLAMPED query indicates whether or not the
|
|
driver supports this control. If it's not supported, gallium frontends may
|
|
have to insert extra clamping code.
|
|
|
|
|
|
clamp_fragment_color
|
|
^^^^^^^^^^^^^^^^^^^^
|
|
|
|
Controls whether TGSI_SEMANTIC_COLOR outputs of the fragment shader
|
|
are clamped to [0, 1].
|
|
|
|
OpenGL: glClampColor(GL_CLAMP_FRAGMENT_COLOR) in GL 3.0 or ARB_color_buffer_float
|
|
|
|
D3D11: seems always disabled
|
|
|
|
Note the PIPE_CAP_FRAGMENT_COLOR_CLAMPED query indicates whether or not the
|
|
driver supports this control. If it's not supported, gallium frontends may
|
|
have to insert extra clamping code.
|
|
|
|
|
|
Shading
|
|
-------
|
|
|
|
flatshade
|
|
^^^^^^^^^
|
|
|
|
If set, the provoking vertex of each polygon is used to determine the color
|
|
of the entire polygon. If not set, fragment colors will be interpolated
|
|
between the vertex colors.
|
|
|
|
The actual interpolated shading algorithm is obviously
|
|
implementation-dependent, but will usually be Gourard for most hardware.
|
|
|
|
.. note::
|
|
|
|
This is separate from the fragment shader input attributes
|
|
CONSTANT, LINEAR and PERSPECTIVE. The flatshade state is needed at
|
|
clipping time to determine how to set the color of new vertices.
|
|
|
|
:ref:`Draw` can implement flat shading by copying the provoking vertex
|
|
color to all the other vertices in the primitive.
|
|
|
|
flatshade_first
|
|
^^^^^^^^^^^^^^^
|
|
|
|
Whether the first vertex should be the provoking vertex, for most primitives.
|
|
If not set, the last vertex is the provoking vertex.
|
|
|
|
There are a few important exceptions to the specification of this rule.
|
|
|
|
* ``PIPE_PRIMITIVE_POLYGON``: The provoking vertex is always the first
|
|
vertex. If the caller wishes to change the provoking vertex, they merely
|
|
need to rotate the vertices themselves.
|
|
* ``PIPE_PRIMITIVE_QUAD``, ``PIPE_PRIMITIVE_QUAD_STRIP``: The option only has
|
|
an effect if ``PIPE_CAP_QUADS_FOLLOW_PROVOKING_VERTEX_CONVENTION`` is true.
|
|
If it is not, the provoking vertex is always the last vertex.
|
|
* ``PIPE_PRIMITIVE_TRIANGLE_FAN``: When set, the provoking vertex is the
|
|
second vertex, not the first. This permits each segment of the fan to have
|
|
a different color.
|
|
|
|
Polygons
|
|
--------
|
|
|
|
light_twoside
|
|
^^^^^^^^^^^^^
|
|
|
|
If set, there are per-vertex back-facing colors. The hardware
|
|
(perhaps assisted by :ref:`Draw`) should be set up to use this state
|
|
along with the front/back information to set the final vertex colors
|
|
prior to rasterization.
|
|
|
|
The frontface vertex shader color output is marked with TGSI semantic
|
|
COLOR[0], and backface COLOR[1].
|
|
|
|
front_ccw
|
|
Indicates whether the window order of front-facing polygons is
|
|
counter-clockwise (TRUE) or clockwise (FALSE).
|
|
|
|
cull_mode
|
|
Indicates which faces of polygons to cull, either PIPE_FACE_NONE
|
|
(cull no polygons), PIPE_FACE_FRONT (cull front-facing polygons),
|
|
PIPE_FACE_BACK (cull back-facing polygons), or
|
|
PIPE_FACE_FRONT_AND_BACK (cull all polygons).
|
|
|
|
fill_front
|
|
Indicates how to fill front-facing polygons, either
|
|
PIPE_POLYGON_MODE_FILL, PIPE_POLYGON_MODE_LINE or
|
|
PIPE_POLYGON_MODE_POINT.
|
|
fill_back
|
|
Indicates how to fill back-facing polygons, either
|
|
PIPE_POLYGON_MODE_FILL, PIPE_POLYGON_MODE_LINE or
|
|
PIPE_POLYGON_MODE_POINT.
|
|
|
|
poly_stipple_enable
|
|
Whether polygon stippling is enabled.
|
|
poly_smooth
|
|
Controls OpenGL-style polygon smoothing/antialiasing
|
|
|
|
offset_point
|
|
If set, point-filled polygons will have polygon offset factors applied
|
|
offset_line
|
|
If set, line-filled polygons will have polygon offset factors applied
|
|
offset_tri
|
|
If set, filled polygons will have polygon offset factors applied
|
|
|
|
offset_units
|
|
Specifies the polygon offset bias
|
|
offset_units_unscaled
|
|
Specifies the unit of the polygon offset bias. If false, use the
|
|
GL/D3D1X behavior. If true, offset_units is a floating point offset
|
|
which isn't scaled (D3D9). Note that GL/D3D1X behavior has different
|
|
formula whether the depth buffer is unorm or float, which is not
|
|
the case for D3D9.
|
|
offset_scale
|
|
Specifies the polygon offset scale
|
|
offset_clamp
|
|
Upper (if > 0) or lower (if < 0) bound on the polygon offset result
|
|
|
|
|
|
|
|
Lines
|
|
-----
|
|
|
|
line_width
|
|
The width of lines.
|
|
line_smooth
|
|
Whether lines should be smoothed. Line smoothing is simply anti-aliasing.
|
|
line_stipple_enable
|
|
Whether line stippling is enabled.
|
|
line_stipple_pattern
|
|
16-bit bitfield of on/off flags, used to pattern the line stipple.
|
|
line_stipple_factor
|
|
When drawing a stippled line, each bit in the stipple pattern is
|
|
repeated N times, where N = line_stipple_factor + 1.
|
|
line_last_pixel
|
|
Controls whether the last pixel in a line is drawn or not. OpenGL
|
|
omits the last pixel to avoid double-drawing pixels at the ends of lines
|
|
when drawing connected lines.
|
|
|
|
|
|
Points
|
|
------
|
|
|
|
sprite_coord_enable
|
|
^^^^^^^^^^^^^^^^^^^
|
|
The effect of this state depends on PIPE_CAP_TGSI_TEXCOORD !
|
|
|
|
Controls automatic texture coordinate generation for rendering sprite points.
|
|
|
|
If PIPE_CAP_TGSI_TEXCOORD is false:
|
|
When bit k in the sprite_coord_enable bitfield is set, then generic
|
|
input k to the fragment shader will get an automatically computed
|
|
texture coordinate.
|
|
|
|
If PIPE_CAP_TGSI_TEXCOORD is true:
|
|
The bitfield refers to inputs with TEXCOORD semantic instead of generic inputs.
|
|
|
|
The texture coordinate will be of the form (s, t, 0, 1) where s varies
|
|
from 0 to 1 from left to right while t varies from 0 to 1 according to
|
|
the state of 'sprite_coord_mode' (see below).
|
|
|
|
If any bit is set, then point_smooth MUST be disabled (there are no
|
|
round sprites) and point_quad_rasterization MUST be true (sprites are
|
|
always rasterized as quads). Any mismatch between these states should
|
|
be considered a bug in the gallium frontend.
|
|
|
|
This feature is implemented in the :ref:`Draw` module but may also be
|
|
implemented natively by GPUs or implemented with a geometry shader.
|
|
|
|
|
|
sprite_coord_mode
|
|
^^^^^^^^^^^^^^^^^
|
|
|
|
Specifies how the value for each shader output should be computed when drawing
|
|
point sprites. For PIPE_SPRITE_COORD_LOWER_LEFT, the lower-left vertex will
|
|
have coordinates (0,0,0,1). For PIPE_SPRITE_COORD_UPPER_LEFT, the upper-left
|
|
vertex will have coordinates (0,0,0,1).
|
|
This state is used by :ref:`Draw` to generate texcoords.
|
|
|
|
|
|
point_quad_rasterization
|
|
^^^^^^^^^^^^^^^^^^^^^^^^
|
|
|
|
Determines if points should be rasterized according to quad or point
|
|
rasterization rules.
|
|
|
|
(Legacy-only) OpenGL actually has quite different rasterization rules
|
|
for points and point sprites - hence this indicates if points should be
|
|
rasterized as points or according to point sprite (which decomposes them
|
|
into quads, basically) rules. Newer GL versions no longer support the old
|
|
point rules at all.
|
|
|
|
Additionally Direct3D will always use quad rasterization rules for
|
|
points, regardless of whether point sprites are enabled or not.
|
|
|
|
If this state is enabled, point smoothing and antialiasing are
|
|
disabled. If it is disabled, point sprite coordinates are not
|
|
generated.
|
|
|
|
.. note::
|
|
|
|
Some renderers always internally translate points into quads; this state
|
|
still affects those renderers by overriding other rasterization state.
|
|
|
|
point_tri_clip
|
|
Determines if clipping of points should happen after they are converted
|
|
to "rectangles" (required by d3d) or before (required by OpenGL, though
|
|
this rule is ignored by some IHVs).
|
|
It is not valid to set this to enabled but have point_quad_rasterization
|
|
disabled.
|
|
point_smooth
|
|
Whether points should be smoothed. Point smoothing turns rectangular
|
|
points into circles or ovals.
|
|
point_size_per_vertex
|
|
Whether the vertex shader is expected to have a point size output.
|
|
Undefined behavior is permitted if there is disagreement between
|
|
this flag and the actual bound shader.
|
|
point_size
|
|
The size of points, if not specified per-vertex.
|
|
|
|
|
|
|
|
Other Members
|
|
-------------
|
|
|
|
scissor
|
|
Whether the scissor test is enabled.
|
|
|
|
multisample
|
|
Whether :term:`MSAA` is enabled.
|
|
|
|
half_pixel_center
|
|
When true, the rasterizer should use (0.5, 0.5) pixel centers for
|
|
determining pixel ownership (e.g, OpenGL, D3D10 and higher)::
|
|
|
|
0 0.5 1
|
|
0 +-----+
|
|
| |
|
|
0.5 | X |
|
|
| |
|
|
1 +-----+
|
|
|
|
When false, the rasterizer should use (0, 0) pixel centers for determining
|
|
pixel ownership (e.g., D3D9 or ealier)::
|
|
|
|
-0.5 0 0.5
|
|
-0.5 +-----+
|
|
| |
|
|
0 | X |
|
|
| |
|
|
0.5 +-----+
|
|
|
|
bottom_edge_rule
|
|
Determines what happens when a pixel sample lies precisely on a triangle
|
|
edge.
|
|
|
|
When true, a pixel sample is considered to lie inside of a triangle if it
|
|
lies on the *bottom edge* or *left edge* (e.g., OpenGL drawables)::
|
|
|
|
0 x
|
|
0 +--------------------->
|
|
|
|
|
| +-------------+
|
|
| | |
|
|
| | |
|
|
| | |
|
|
| +=============+
|
|
|
|
|
y V
|
|
|
|
When false, a pixel sample is considered to lie inside of a triangle if it
|
|
lies on the *top edge* or *left edge* (e.g., OpenGL FBOs, D3D)::
|
|
|
|
0 x
|
|
0 +--------------------->
|
|
|
|
|
| +=============+
|
|
| | |
|
|
| | |
|
|
| | |
|
|
| +-------------+
|
|
|
|
|
y V
|
|
|
|
Where:
|
|
- a *top edge* is an edge that is horizontal and is above the other edges;
|
|
- a *bottom edge* is an edge that is horizontal and is below the other
|
|
edges;
|
|
- a *left edge* is an edge that is not horizontal and is on the left side of
|
|
the triangle.
|
|
|
|
.. note::
|
|
|
|
Actually all graphics APIs use a top-left rasterization rule for pixel
|
|
ownership, but their notion of top varies with the axis origin (which
|
|
can be either at y = 0 or at y = height). Gallium instead always
|
|
assumes that top is always at y=0.
|
|
|
|
See also:
|
|
- http://msdn.microsoft.com/en-us/library/windows/desktop/cc627092.aspx
|
|
- http://msdn.microsoft.com/en-us/library/windows/desktop/bb147314.aspx
|
|
|
|
clip_halfz
|
|
When true clip space in the z axis goes from [0..1] (D3D). When false
|
|
[-1, 1] (GL)
|
|
|
|
depth_clip
|
|
When false, the near and far depth clipping planes of the view volume are
|
|
disabled and the depth value will be clamped at the per-pixel level, after
|
|
polygon offset has been applied and before depth testing.
|
|
|
|
clip_plane_enable
|
|
For each k in [0, PIPE_MAX_CLIP_PLANES), if bit k of this field is set,
|
|
clipping half-space k is enabled, if it is clear, it is disabled.
|
|
The clipping half-spaces are defined either by the user clip planes in
|
|
``pipe_clip_state``, or by the clip distance outputs of the shader stage
|
|
preceding the fragment shader.
|
|
If any clip distance output is written, those half-spaces for which no
|
|
clip distance is written count as disabled; i.e. user clip planes and
|
|
shader clip distances cannot be mixed, and clip distances take precedence.
|
|
|
|
conservative_raster_mode
|
|
The conservative rasterization mode. For PIPE_CONSERVATIVE_RASTER_OFF,
|
|
conservative rasterization is disabled. For IPE_CONSERVATIVE_RASTER_POST_SNAP
|
|
or PIPE_CONSERVATIVE_RASTER_PRE_SNAP, conservative rasterization is nabled.
|
|
When conservative rasterization is enabled, the polygon smooth, line mooth,
|
|
point smooth and line stipple settings are ignored.
|
|
With the post-snap mode, unlike the pre-snap mode, fragments are never
|
|
generated for degenerate primitives. Degenerate primitives, when rasterized,
|
|
are considered back-facing and the vertex attributes and depth are that of
|
|
the provoking vertex.
|
|
If the post-snap mode is used with an unsupported primitive, the pre-snap
|
|
mode is used, if supported. Behavior is similar for the pre-snap mode.
|
|
If the pre-snap mode is used, fragments are generated with respect to the primitive
|
|
before vertex snapping.
|
|
|
|
conservative_raster_dilate
|
|
The amount of dilation during conservative rasterization.
|
|
|
|
subpixel_precision_x
|
|
A bias added to the horizontal subpixel precision during conservative rasterization.
|
|
subpixel_precision_y
|
|
A bias added to the vertical subpixel precision during conservative rasterization.
|