Attributes include polygon culling state, line width, line stipple,
multisample state, scissoring and flat/smooth shading.
-
-Members
+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.
- Note that this is separate from the fragment shader input attributes
- CONSTANT, LINEAR and PERSPECTIVE. We need the flatshade state at
+^^^^^^^^^
+
+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.
- Also note that the draw module can implement flat shading by copying
- the provoking vertex color to all the other vertices in the primitive.
+
+ :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.
+^^^^^^^^^^^^^^^
+
+Whether the first vertex should be the provoking vertex, for most primitives.
+If not set, the last vertex is the provoking vertex.
+
+There are several 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``: This option has no
+ effect; 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.
+
+Points
+------
+
+sprite_coord_enable
+^^^^^^^^^^^^^^^^^^^
+
+Specifies if a texture unit has its texture coordinates replaced or not. This
+is a packed bitfield containing the enable for all texcoords -- if all bits
+are zero, point sprites are effectively disabled. If any bit is set, then
+point_smooth and point_quad_rasterization are ignored; point smoothing is
+disabled and points are always rasterized as quads. If enabled, the four
+vertices of the resulting quad will be assigned texture coordinates,
+according to sprite_coord_mode.
+
+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.
+
+.. note::
+
+ When geometry shaders are available, a special geometry shader could be
+ used instead of this functionality, to convert incoming points into quads
+ with the proper texture coordinates.
+
+point_quad_rasterization
+^^^^^^^^^^^^^^^^^^^^^^^^
+
+Determines if points should be rasterized as quads or points. Certain APIs,
+like Direct3D, always use quad rasterization 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.
+
+Other Members
+^^^^^^^^^^^^^
light_twoside
- If set, there are per-vertex back-facing colors. The draw module
+ If set, there are per-vertex back-facing colors. :ref:`Draw`
uses this state along with the front/back information to set the
final vertex colors prior to rasterization.
front_winding
Indicates the window order of front-facing polygons, either
PIPE_WINDING_CW or PIPE_WINDING_CCW
+
cull_mode
Indicates which polygons to cull, either PIPE_WINDING_NONE (cull no
polygons), PIPE_WINDING_CW (cull clockwise-winding polygons),
line_stipple_pattern
16-bit bitfield of on/off flags, used to pattern the line stipple.
line_stipple_factor
- When drawinga stippled line, each bit in the stipple pattern is
+ 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
Whether vertices have a point size element.
point_size
The size of points, if not specified per-vertex.
-point_size_min
- The minimum size of points.
-point_size_max
- The maximum size of points.
-point_sprite
- Whether points are drawn as sprites (textured quads)
-sprite_coord_mode
- Specifies how the value for each shader output should be computed when
- drawing sprites. If PIPE_SPRITE_COORD_NONE, don't change the vertex
- shader output. Otherwise, the four vertices of the resulting quad will
- be assigned texture coordinates. For PIPE_SPRITE_COORD_LOWER_LEFT, the
- lower left vertex will have coordinate (0,0,0,1).
- For PIPE_SPRITE_COORD_UPPER_LEFT, the upper-left vertex will have
- coordinate (0,0,0,1).
- This state is needed by the 'draw' module because that's where each
- point vertex is converted into four quad vertices. There's no other
- place to emit the new vertex texture coordinates which are required for
- sprite rendering.
- Note that when geometry shaders are available, this state could be
- removed. A special geometry shader defined by the state tracker could
- converts the incoming points into quads with the proper texture coords.
scissor
Whether the scissor test is enabled.
multisample
- Whether :ref:`MSAA` is enabled.
-
-bypass_vs_clip_and_viewport
- Whether the entire TCL pipeline should be bypassed. This implies that
- vertices are pre-transformed for the viewport, and will not be run
- through the vertex shader. Note that implementations may still clip away
- vertices that are not in the viewport.
+ 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.
-
-Notes
------
-
-flatshade
-^^^^^^^^^
-
-The actual interpolated shading algorithm is obviously
-implementation-dependent, but will usually be Gourard for most hardware.
-
-bypass_vs_clip_and_viewport
-^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-When set, this implies that vertices are pre-transformed for the viewport, and
-will not be run through the vertex shader. Note that implementations may still
-clip away vertices that are not visible.
-
-flatshade_first
-^^^^^^^^^^^^^^^
-
-There are several 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``: This option has no
- effect; 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.
projects / mesa.git / blobdiff