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diff --git a/src/gallium/docs/source/cso/rasterizer.rst b/src/gallium/docs/source/cso/rasterizer.rst new file mode 100644 index 0000000000..4d8e1708e7 --- /dev/null +++ b/src/gallium/docs/source/cso/rasterizer.rst @@ -0,0 +1,152 @@ +.. _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. + + +Members +------- + +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 + 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. + +flatshade_first + Whether the first vertex should be the provoking vertex, for most + primitives. If not set, the last vertex is the provoking vertex. + +light_twoside + If set, there are per-vertex back-facing colors. The draw module + 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), + PIPE_WINDING_CCW (cull counter clockwise-winding polygons), or + PIPE_WINDING_BOTH (cull all polygons). + +fill_cw + Indicates how to fill clockwise polygons, either PIPE_POLYGON_MODE_FILL, + PIPE_POLYGON_MODE_LINE or PIPE_POLYGON_MODE_POINT. +fill_ccw + Indicates how to fill counter clockwise 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_cw + If set, clockwise polygons will have polygon offset factors applied +offset_ccw + If set, counter clockwise polygons will have polygon offset factors applied +offset_units + Specifies the polygon offset bias +offset_scale + Specifies the polygon offset scale + +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 drawinga 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. + +point_smooth + Whether points should be smoothed. Point smoothing turns rectangular + points into circles or ovals. +point_size_per_vertex + 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. + +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. |