1 .. _sampler: 2 3 Sampler 4 ======= 5 6 Texture units have many options for selecting texels from loaded textures; 7 this state controls an individual texture unit's texel-sampling settings. 8 9 Texture coordinates are always treated as four-dimensional, and referred to 10 with the traditional (S, T, R, Q) notation. 11 12 Members 13 ------- 14 15 wrap_s 16 How to wrap the S coordinate. One of PIPE_TEX_WRAP_*. 17 wrap_t 18 How to wrap the T coordinate. One of PIPE_TEX_WRAP_*. 19 wrap_r 20 How to wrap the R coordinate. One of PIPE_TEX_WRAP_*. 21 22 The wrap modes are: 23 24 * ``PIPE_TEX_WRAP_REPEAT``: Standard coord repeat/wrap-around mode. 25 * ``PIPE_TEX_WRAP_CLAMP_TO_EDGE``: Clamp coord to edge of texture, the border 26 color is never sampled. 27 * ``PIPE_TEX_WRAP_CLAMP_TO_BORDER``: Clamp coord to border of texture, the 28 border color is sampled when coords go outside the range [0,1]. 29 * ``PIPE_TEX_WRAP_CLAMP``: The coord is clamped to the range [0,1] before 30 scaling to the texture size. This corresponds to the legacy OpenGL GL_CLAMP 31 texture wrap mode. Historically, this mode hasn't acted consistantly across 32 all graphics hardware. It sometimes acts like CLAMP_TO_EDGE or 33 CLAMP_TO_BORDER. The behaviour may also vary depending on linear vs. 34 nearest sampling mode. 35 * ``PIPE_TEX_WRAP_MIRROR_REPEAT``: If the integer part of the coordinate 36 is odd, the coord becomes (1 - coord). Then, normal texture REPEAT is 37 applied to the coord. 38 * ``PIPE_TEX_WRAP_MIRROR_CLAMP_TO_EDGE``: First, the absolute value of the 39 coordinate is computed. Then, regular CLAMP_TO_EDGE is applied to the coord. 40 * ``PIPE_TEX_WRAP_MIRROR_CLAMP_TO_BORDER``: First, the absolute value of the 41 coordinate is computed. Then, regular CLAMP_TO_BORDER is applied to the 42 coord. 43 * ``PIPE_TEX_WRAP_MIRROR_CLAMP``: First, the absolute value of the coord is 44 computed. Then, regular CLAMP is applied to the coord. 45 46 47 min_img_filter 48 The image filter to use when minifying texels. One of PIPE_TEX_FILTER_*. 49 mag_img_filter 50 The image filter to use when magnifying texels. One of PIPE_TEX_FILTER_*. 51 52 The texture image filter modes are: 53 54 * ``PIPE_TEX_FILTER_NEAREST``: One texel is fetched from the texture image 55 at the texture coordinate. 56 * ``PIPE_TEX_FILTER_LINEAR``: Two, four or eight texels (depending on the 57 texture dimensions; 1D/2D/3D) are fetched from the texture image and 58 linearly weighted and blended together. 59 60 min_mip_filter 61 The filter to use when minifying mipmapped textures. One of 62 PIPE_TEX_MIPFILTER_*. 63 64 The texture mip filter modes are: 65 66 * ``PIPE_TEX_MIPFILTER_NEAREST``: A single mipmap level/image is selected 67 according to the texture LOD (lambda) value. 68 * ``PIPE_TEX_MIPFILTER_LINEAR``: The two mipmap levels/images above/below 69 the texture LOD value are sampled from. The results of sampling from 70 those two images are blended together with linear interpolation. 71 * ``PIPE_TEX_MIPFILTER_NONE``: Mipmap filtering is disabled. All texels 72 are taken from the level 0 image. 73 74 75 compare_mode 76 If set to PIPE_TEX_COMPARE_R_TO_TEXTURE, the result of texture sampling 77 is not a color but a true/false value which is the result of comparing the 78 sampled texture value (typically a Z value from a depth texture) to the 79 texture coordinate's R component. 80 If set to PIPE_TEX_COMPARE_NONE, no comparison calculation is performed. 81 compare_func 82 The inequality operator used when compare_mode=1. One of PIPE_FUNC_x. 83 normalized_coords 84 If set, the incoming texture coordinates (nominally in the range [0,1]) 85 will be scaled by the texture width, height, depth to compute texel 86 addresses. Otherwise, the texture coords are used as-is (they are not 87 scaled by the texture dimensions). 88 When normalized_coords=0, only a subset of the texture wrap modes are 89 allowed: PIPE_TEX_WRAP_CLAMP, PIPE_TEX_WRAP_CLAMP_TO_EDGE and 90 PIPE_TEX_WRAP_CLAMP_TO_BORDER. 91 lod_bias 92 Bias factor which is added to the computed level of detail. 93 The normal level of detail is computed from the partial derivatives of 94 the texture coordinates and/or the fragment shader TEX/TXB/TXL 95 instruction. 96 min_lod 97 Minimum level of detail, used to clamp LOD after bias. The LOD values 98 correspond to mipmap levels where LOD=0 is the level 0 mipmap image. 99 max_lod 100 Maximum level of detail, used to clamp LOD after bias. 101 border_color 102 Color union used for texel coordinates that are outside the [0,width-1], 103 [0, height-1] or [0, depth-1] ranges. Interpreted according to sampler 104 view format. 105 max_anisotropy 106 Maximum anistropy ratio to use when sampling from textures. For example, 107 if max_anistropy=4, a region of up to 1 by 4 texels will be sampled. 108 Set to zero to disable anisotropic filtering. Any other setting enables 109 anisotropic filtering, however it's not unexpected some drivers only will 110 change their filtering with a setting of 2 and higher. 111 seamless_cube_map 112 If set, the bilinear filter of a cube map may take samples from adjacent 113 cube map faces when sampled near a texture border to produce a seamless 114 look.
