src/gallium/docs/source/cso/rasterizer.rst - platform/external/mesa3d - Git at Google

 .. _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, the state tracker 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, the state tracker 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_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
 ^^^^^^^^^^^^^^^^^^^

 Controls automatic texture coordinate generation for rendering sprite points.

 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.

 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 state-tracker.

 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.

 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.

 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_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 behaviour 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.

 gl_rasterization_rules
     Whether the rasterizer should use (0.5, 0.5) pixel centers. When not set,
     the rasterizer will use (0, 0) for pixel centers.

 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.
	.. _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, the state tracker 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, the state tracker 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_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
	^^^^^^^^^^^^^^^^^^^

	Controls automatic texture coordinate generation for rendering sprite points.

	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.

	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 state-tracker.

	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.

	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.

	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_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 behaviour 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.

	gl_rasterization_rules
	Whether the rasterizer should use (0.5, 0.5) pixel centers. When not set,
	the rasterizer will use (0, 0) for pixel centers.

	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.