forked from Qortal/Brooklyn
117 lines
5.1 KiB
ReStructuredText
117 lines
5.1 KiB
ReStructuredText
.. _sampler:
|
|
|
|
Sampler
|
|
=======
|
|
|
|
Texture units have many options for selecting texels from loaded textures;
|
|
this state controls an individual texture unit's texel-sampling settings.
|
|
|
|
Texture coordinates are always treated as four-dimensional, and referred to
|
|
with the traditional (S, T, R, Q) notation.
|
|
|
|
Members
|
|
-------
|
|
|
|
wrap_s
|
|
How to wrap the S coordinate. One of PIPE_TEX_WRAP_*.
|
|
wrap_t
|
|
How to wrap the T coordinate. One of PIPE_TEX_WRAP_*.
|
|
wrap_r
|
|
How to wrap the R coordinate. One of PIPE_TEX_WRAP_*.
|
|
|
|
The wrap modes are:
|
|
|
|
* ``PIPE_TEX_WRAP_REPEAT``: Standard coord repeat/wrap-around mode.
|
|
* ``PIPE_TEX_WRAP_CLAMP_TO_EDGE``: Clamp coord to edge of texture, the border
|
|
color is never sampled.
|
|
* ``PIPE_TEX_WRAP_CLAMP_TO_BORDER``: Clamp coord to border of texture, the
|
|
border color is sampled when coords go outside the range [0,1].
|
|
* ``PIPE_TEX_WRAP_CLAMP``: The coord is clamped to the range [0,1] before
|
|
scaling to the texture size. This corresponds to the legacy OpenGL GL_CLAMP
|
|
texture wrap mode. Historically, this mode hasn't acted consistently across
|
|
all graphics hardware. It sometimes acts like CLAMP_TO_EDGE or
|
|
CLAMP_TO_BORDER. The behavior may also vary depending on linear vs.
|
|
nearest sampling mode.
|
|
* ``PIPE_TEX_WRAP_MIRROR_REPEAT``: If the integer part of the coordinate
|
|
is odd, the coord becomes (1 - coord). Then, normal texture REPEAT is
|
|
applied to the coord.
|
|
* ``PIPE_TEX_WRAP_MIRROR_CLAMP_TO_EDGE``: First, the absolute value of the
|
|
coordinate is computed. Then, regular CLAMP_TO_EDGE is applied to the coord.
|
|
* ``PIPE_TEX_WRAP_MIRROR_CLAMP_TO_BORDER``: First, the absolute value of the
|
|
coordinate is computed. Then, regular CLAMP_TO_BORDER is applied to the
|
|
coord.
|
|
* ``PIPE_TEX_WRAP_MIRROR_CLAMP``: First, the absolute value of the coord is
|
|
computed. Then, regular CLAMP is applied to the coord.
|
|
|
|
|
|
min_img_filter
|
|
The image filter to use when minifying texels. One of PIPE_TEX_FILTER_*.
|
|
mag_img_filter
|
|
The image filter to use when magnifying texels. One of PIPE_TEX_FILTER_*.
|
|
|
|
The texture image filter modes are:
|
|
|
|
* ``PIPE_TEX_FILTER_NEAREST``: One texel is fetched from the texture image
|
|
at the texture coordinate.
|
|
* ``PIPE_TEX_FILTER_LINEAR``: Two, four or eight texels (depending on the
|
|
texture dimensions; 1D/2D/3D) are fetched from the texture image and
|
|
linearly weighted and blended together.
|
|
|
|
min_mip_filter
|
|
The filter to use when minifying mipmapped textures. One of
|
|
PIPE_TEX_MIPFILTER_*.
|
|
|
|
The texture mip filter modes are:
|
|
|
|
* ``PIPE_TEX_MIPFILTER_NEAREST``: A single mipmap level/image is selected
|
|
according to the texture LOD (lambda) value.
|
|
* ``PIPE_TEX_MIPFILTER_LINEAR``: The two mipmap levels/images above/below
|
|
the texture LOD value are sampled from. The results of sampling from
|
|
those two images are blended together with linear interpolation.
|
|
* ``PIPE_TEX_MIPFILTER_NONE``: Mipmap filtering is disabled. All texels
|
|
are taken from the level 0 image.
|
|
|
|
|
|
compare_mode
|
|
If set to PIPE_TEX_COMPARE_R_TO_TEXTURE, the result of texture sampling
|
|
is not a color but a true/false value which is the result of comparing the
|
|
sampled texture value (typically a Z value from a depth texture) to the
|
|
texture coordinate's R component.
|
|
If set to PIPE_TEX_COMPARE_NONE, no comparison calculation is performed.
|
|
compare_func
|
|
The inequality operator used when compare_mode=1. One of PIPE_FUNC_x.
|
|
normalized_coords
|
|
If set, the incoming texture coordinates (nominally in the range [0,1])
|
|
will be scaled by the texture width, height, depth to compute texel
|
|
addresses. Otherwise, the texture coords are used as-is (they are not
|
|
scaled by the texture dimensions).
|
|
When normalized_coords=0, only a subset of the texture wrap modes are
|
|
allowed: PIPE_TEX_WRAP_CLAMP, PIPE_TEX_WRAP_CLAMP_TO_EDGE and
|
|
PIPE_TEX_WRAP_CLAMP_TO_BORDER.
|
|
lod_bias
|
|
Bias factor which is added to the computed level of detail.
|
|
The normal level of detail is computed from the partial derivatives of
|
|
the texture coordinates and/or the fragment shader TEX/TXB/TXL
|
|
instruction.
|
|
min_lod
|
|
Minimum level of detail, used to clamp LOD after bias. The LOD values
|
|
correspond to mipmap levels where LOD=0 is the level 0 mipmap image.
|
|
max_lod
|
|
Maximum level of detail, used to clamp LOD after bias.
|
|
border_color
|
|
Color union used for texel coordinates that are outside the [0,width-1],
|
|
[0, height-1] or [0, depth-1] ranges. Interpreted according to sampler
|
|
view format, unless the driver reports
|
|
PIPE_CAP_TEXTURE_BORDER_COLOR_QUIRK, in which case special care has to be
|
|
taken (see description of the cap).
|
|
max_anisotropy
|
|
Maximum anisotropy ratio to use when sampling from textures. For example,
|
|
if max_anisotropy=4, a region of up to 1 by 4 texels will be sampled.
|
|
Set to zero to disable anisotropic filtering. Any other setting enables
|
|
anisotropic filtering, however it's not unexpected some drivers only will
|
|
change their filtering with a setting of 2 and higher.
|
|
seamless_cube_map
|
|
If set, the bilinear filter of a cube map may take samples from adjacent
|
|
cube map faces when sampled near a texture border to produce a seamless
|
|
look.
|