The sign will be preserved if available in the target format. If the lower format does not have an INF representation, it will be converted to the maximum value representable. INF in a higher range format will be converted to INF in the lower range format if available.If the lower format does not have a NaN representation, the result will be 0. NaN in a higher range format will be converted to NaN representation in the lower range format if the NaN representation exists in the lower range format.a large 32-bit float value is written into a 16-bit float RenderTarget), the maximum representable (appropriately signed) value results, NOT including signed infinity (due to the round to zero described above). For source values greater than the dynamic range of a lower range target format (eg.Finally, the float-to-fixed conversions used by the texture sampler and rasterizer have a specified tolerance measured in Unit-Last-Place from an infinitely precise ideal. Other exceptions are the ftoi and ftou shader instructions, which use round-to-zero. If the target is an integer or fixed point format, round-to-nearest-even is used, unless the conversion is explicitly documented as using another rounding behavior, such as round-to-nearest for FLOAT to SNORM, FLOAT to UNORM or FLOAT to SRGB. Round-to-zero is used during conversion to another float format.Conververting from a higher range representation to a lower range representation Whenever a floating point conversion between different representations occurs, including to or from non-floating point representations, the following rules apply. For complete detail, refer to the SRGB color standard, IEC 6, at IEC (International Electrotechnical Commission). Roughly, if this nonlinear progression, SRGB, is displayed as a sequence of colors, it would appear as a linear ramp of luminosity levels to an "average" observer, under "average" viewing conditions, on an "average" display. However unlike UNORM, with SRGB the sequence of unsigned integer encodings between all 0's to all 1's represent a nonlinear progression in the floating point interpretation of the numbers, between 0.0f to 1.0f. Similar to UNORM, in that for an n-bit number, all 0's means 0.0f and all 1's means 1.0f. a 3-bit UINT represents the integral values 0, 1, 2, 3, 4, 5, 6, 7.Ī floating-point value in any of the representations defined by Direct3D.
an 3-bit SINT represents the integral values -4, -3, -2, -1, 0, 1, 2, 3. A sequence of evenly spaced floating point values from 0.0f to 1.0f are represented. Unsigned normalized integer, meaning that for an n-bit number, all 0's means 0.0f, and all 1's means 1.0f. This results in a set of integer representations for evenly spaced floating point values in the range (-1.0f.0.0f), and also a complementary set of representations for numbers in the range (0.0f.1.0f) There is a single representation for 0.0f, and a single representation for 1.0f. There are thus two integer representations for -1.0f. In addition, the second-minimum number maps to -1.0f (e.g. the 5-bit value 01111 maps to 1.0f), and the minimum value means -1.0f (e.g. Signed normalized integer, meaning that for an n-bit 2's complement number, the maximum value means 1.0f (e.g. The following set of terms are subsequently used to characterize various format conversions. Converting from a lower range representation to a higher range representation.
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