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TINYGL: Fix ARGBST scaling.

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I based ARGB scaling on ST scaling without giving it enough thought.
It accidentally uncovered an older bug in glopClear, which made me recheck
these formulas.
ST scaling maps [0.0, 1.0] to [0x01.0000, 0xff.0000], meaning the first and
last texture rows and columns are never shown.
Treating s and t as proportions of ST_MAX fixes this by mapping to
[0x00.0000, 0xff.fffc] (last two fractional bits being off-precision, as
there are only 14 bits), covering the whole available range.
This commit is contained in:
Vincent Pelletier 2017-05-01 08:28:55 +00:00
parent 8c1954359e
commit 4bcc95f217
3 changed files with 15 additions and 24 deletions
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8
graphics/tinygl/api.cpp
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@ -82,10 +82,10 @@ void tglColor4f(float r, float g, float b, float a) {
p[3].f = b;
p[4].f = a;
// direct convertion to integer to go faster if no shading
p[5].ui = (unsigned int)(r * (ZB_POINT_RED_MAX - ZB_POINT_RED_MIN) + ZB_POINT_RED_MIN);
p[6].ui = (unsigned int)(g * (ZB_POINT_GREEN_MAX - ZB_POINT_GREEN_MIN) + ZB_POINT_GREEN_MIN);
p[7].ui = (unsigned int)(b * (ZB_POINT_BLUE_MAX - ZB_POINT_BLUE_MIN) + ZB_POINT_BLUE_MIN);
p[8].ui = (unsigned int)(a * (ZB_POINT_ALPHA_MAX - ZB_POINT_ALPHA_MIN) + ZB_POINT_ALPHA_MIN);
p[5].ui = (unsigned int)(r * ZB_POINT_RED_MAX);
p[6].ui = (unsigned int)(g * ZB_POINT_GREEN_MAX);
p[7].ui = (unsigned int)(b * ZB_POINT_BLUE_MAX);
p[8].ui = (unsigned int)(a * ZB_POINT_ALPHA_MAX);
gl_add_op(p);
}