diff options
Diffstat (limited to 'src/gallium/docs')
| -rw-r--r-- | src/gallium/docs/source/tgsi.rst | 47 |
1 files changed, 44 insertions, 3 deletions
diff --git a/src/gallium/docs/source/tgsi.rst b/src/gallium/docs/source/tgsi.rst index 2c34a6bae5e..3e702ceeda4 100644 --- a/src/gallium/docs/source/tgsi.rst +++ b/src/gallium/docs/source/tgsi.rst @@ -1319,9 +1319,8 @@ are the Cartesian coordinates, and ``w`` is the homogenous coordinate and used for the perspective divide, if enabled. As a vertex shader output, position should be scaled to the viewport. When -used in fragment shaders, position will --- - -XXX --- wait a minute. Should position be in [0,1] for x and y? +used in fragment shaders, position will be in window coordinates. The convention +used depends on the FS_COORD_ORIGIN and FS_COORD_PIXEL_CENTER properties. XXX additionally, is there a way to configure the perspective divide? it's accelerated on most chipsets AFAIK... @@ -1400,3 +1399,45 @@ TGSI_SEMANTIC_EDGEFLAG """""""""""""""""""""" XXX no clue + + +Properties +^^^^^^^^^^^^^^^^^^^^^^^^ + + + Properties are general directives that apply to the whole TGSI program. + +FS_COORD_ORIGIN +""""""""""""""" + +Specifies the fragment shader TGSI_SEMANTIC_POSITION coordinate origin. +The default value is UPPER_LEFT. + +If UPPER_LEFT, the position will be (0,0) at the upper left corner and +increase downward and rightward. +If LOWER_LEFT, the position will be (0,0) at the lower left corner and +increase upward and rightward. + +OpenGL defaults to LOWER_LEFT, and is configurable with the +GL_ARB_fragment_coord_conventions extension. + +DirectX 9/10 use UPPER_LEFT. + +FS_COORD_PIXEL_CENTER +""""""""""""""""""""" + +Specifies the fragment shader TGSI_SEMANTIC_POSITION pixel center convention. +The default value is HALF_INTEGER. + +If HALF_INTEGER, the fractionary part of the position will be 0.5 +If INTEGER, the fractionary part of the position will be 0.0 + +Note that this does not affect the set of fragments generated by +rasterization, which is instead controlled by gl_rasterization_rules in the +rasterizer. + +OpenGL defaults to HALF_INTEGER, and is configurable with the +GL_ARB_fragment_coord_conventions extension. + +DirectX 9 uses INTEGER. +DirectX 10 uses HALF_INTEGER. |