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| author | Kenneth Graunke <kenneth@whitecape.org> | 2012-10-12 11:17:39 -0700 |
|---|---|---|
| committer | Kenneth Graunke <kenneth@whitecape.org> | 2012-11-21 20:29:38 -0800 |
| commit | e9967aba61a7cc62ce13ab691d14bb5a26a86896 (patch) | |
| tree | 106d600c4ca297d1ad78feb08dc567d7fe5b7763 /src | |
| parent | e2df37f69a4e513b756fc193a544d48d8fd0ddac (diff) | |
| download | external_mesa3d-e9967aba61a7cc62ce13ab691d14bb5a26a86896.zip external_mesa3d-e9967aba61a7cc62ce13ab691d14bb5a26a86896.tar.gz external_mesa3d-e9967aba61a7cc62ce13ab691d14bb5a26a86896.tar.bz2 | |
mesa/vbo: Fix scaling issue in 10-bit signed normalized packing.
For the 10-bit components, the divisor was incorrect. A 10-bit signed
integer can represent -2^9 through 2^9 - 1, which leads to the following
ranges:
(float)value.x -> [ -512, 511]
2.0F * (float)value.x -> [-1024, 1022]
2.0F * (float)value.x + 1.0F -> [-1023, 1023]
So dividing by 511 would incorrectly scale it to approximately:
[-2.001956947, 2.001956947]. To correctly scale to [-1.0, 1.0], we need
to divide by 1023.
This correctly implements the desktop GL rules. ES 3.0 has different
rules, but those will be implemented in a separate patch.
Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Tested-by: Marek Olšák <maraeo@gmail.com>
Diffstat (limited to 'src')
| -rw-r--r-- | src/mesa/vbo/vbo_attrib_tmp.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/src/mesa/vbo/vbo_attrib_tmp.h b/src/mesa/vbo/vbo_attrib_tmp.h index 6bc53ba..9a4df69 100644 --- a/src/mesa/vbo/vbo_attrib_tmp.h +++ b/src/mesa/vbo/vbo_attrib_tmp.h @@ -117,7 +117,7 @@ static inline float conv_i10_to_norm_float(int i10) { struct attr_bits_10 val; val.x = i10; - return (2.0F * (float)val.x + 1.0F) * (1.0F / 511.0F); + return (2.0F * (float)val.x + 1.0F) * (1.0F / 1023.0F); } static inline float conv_i2_to_norm_float(int i2) |