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gallium: better docs for pipe_rasterizer_state::sprite_coord_enable

This commit is contained in:
Brian Paul 2010-09-17 18:41:05 -06:00
parent fd266ec62c
commit 49cb978aa4
1 changed files with 13 additions and 5 deletions
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18
src/gallium/docs/source/cso/rasterizer.rst
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@ -124,17 +124,24 @@ 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.
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.
If enabled, the four vertices of the resulting quad will be assigned
texture coordinates, according to sprite_coord_mode.
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
^^^^^^^^^^^^^^^^^
@ -145,6 +152,7 @@ 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
^^^^^^^^^^^^^^^^^^^^^^^^