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Tier 2

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Tier 2 support for streaming resources adds capabilities beyond Tier 1, such as guaranteeing nonpacked texture mipmap when the size is at least one standard tile shape; shader instructions for clamping level-of-detail (LOD) and for obtaining status about the shader operation; also, reading from NULL-mapped tiles treat that sampled value as zero.

Tier 2 general support

Tier 2 support includes the following.

  • Hardware at Feature Level 11.1 minimum.
  • All features of the previous tier (without Tier 1 specific limitations) plus the additions in these following items:
  • Shader instructions for clamping LOD and mapped status feedback are available. See HLSL streaming resources exposure.

In addition to these, there are some specific support issues that follow.

Non-mapped tiles

Reads from non-mapped tiles return 0 in all non-missing components of the format, and the default for missing components.

Writes to non-mapped tiles are stopped from going to memory but might end up in caches that subsequent reads to the same address might or might not pick up.

Texture filtering

Texture filtering with a footprint that straddles NULL and non-NULL tiles contributes 0 (with defaults for missing format components) for texels on NULL tiles into the overall filter operation. Some early hardware don't meet this requirement and returns 0 (with defaults for missing format components) for the full filter result if any texels (with nonzero weight) fall on a NULL tile. No other hardware will be allowed to miss the requirement to include all (nonzero weighted) texels in the filter operation.

NULL texel accesses cause the CheckAccessFullyMapped operation on the status feedback for a texture read to return false. This is regardless of how the texture access result might get write masked in the shader and how many components are in the texture format (the combination of which might make it appear that the texture does not need to be accessed).

Alignment constraints

Alignment constraints for standard tile shapes: Mipmaps that fill at least one standard tile in all dimensions are guaranteed to use the standard tiling, with the remainder considered packed as a unit into N tiles (N reported to the application). The application can map the N tiles into arbitrarily disjoint locations in a tile pool, but must either map all or none of the packed tiles. The mip packing is a unique set of packed tiles per array slice.

Min/Max reduction filtering

Min/Max reduction filtering is supported. See Streaming resources texture sampling features.

Limitations

Streaming resources with any mipmaps less than standard tile size in any dimension are not allowed to have an array size larger than 1.

Limitations on how tiles can be accessed when there are duplicate mappings continue to apply. See Tile access limitations with duplicate mappings.

Streaming resources features tiers