+++ /dev/null
-.. _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 consistantly across
- all graphics hardware. It sometimes acts like CLAMP_TO_EDGE or
- CLAMP_TO_BORDER. The behaviour 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 anistropy ratio to use when sampling from textures. For example,
- if max_anistropy=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.
projects / mesa.git / blobdiff