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Add lerp quality

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This commit is contained in:
Miloslav Číž 2019-05-06 01:11:24 +02:00
parent 529c02a7a4
commit 5849cc6f17
1 changed files with 23 additions and 7 deletions
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30
s3l.h
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@ -121,6 +121,13 @@ typedef int32_t S3L_Unit; /**< Units of measurement in 3D space. There is
it will overflow. Also other things
may overflow, so rather don't do it. */
#define S3L_LERP_QUALITY 3 /**< Quality (scaling) of SOME linear interpolations.
0 will most likely be faster, but artifacts can
occur, while higher values can fix this -- in
theory all higher values will have the same
speed (it is a shift value), but it mustn't be
too high to prevent overflow (3 seems okay). */
#define S3L_nonzero(value) ((value) != 0 ? (value) : 1) /**< prevents division
by zero */
@ -771,16 +778,16 @@ void S3L_drawTriangle(
p2 - point to (t, l or r)
down - whether the side coordinate goes top-down or vice versa
*/
#define initSide(s,p1,p2,down)\
s##X = p1##PointX;\
s##Dx = p2##PointX - p1##PointX;\
s##Dy = p2##PointY - p1##PointY;\
s##SideUnitStep = S3L_FRACTIONS_PER_UNIT / (s##Dy != 0 ? s##Dy : 1);\
s##SideUnitStep = (S3L_FRACTIONS_PER_UNIT << S3L_LERP_QUALITY)\
/ (s##Dy != 0 ? s##Dy : 1);\
s##SideUnitPos = 0;\
if (!down)\
{\
s##SideUnitPos = S3L_FRACTIONS_PER_UNIT;\
s##SideUnitPos = S3L_FRACTIONS_PER_UNIT << S3L_LERP_QUALITY;\
s##SideUnitStep *= -1;\
}\
s##Inc = s##Dx >= 0 ? 1 : -1;\
@ -818,7 +825,9 @@ void S3L_drawTriangle(
barycentric0 = barycentric2;
barycentric2 = tmp;
rSideUnitPos = S3L_FRACTIONS_PER_UNIT - rSideUnitPos;
rSideUnitPos = (S3L_FRACTIONS_PER_UNIT << S3L_LERP_QUALITY)
- rSideUnitPos;
rSideUnitStep *= -1;
}
else
@ -829,7 +838,9 @@ void S3L_drawTriangle(
barycentric1 = barycentric2;
barycentric2 = tmp;
lSideUnitPos = S3L_FRACTIONS_PER_UNIT - lSideUnitPos;
lSideUnitPos = (S3L_FRACTIONS_PER_UNIT << S3L_LERP_QUALITY)
- lSideUnitPos;
lSideUnitStep *= -1;
}
}
@ -847,8 +858,13 @@ void S3L_drawTriangle(
for (S3L_ScreenCoord x = lX; x < rX; ++x)
{
*barycentric0 = S3L_interpolateFrom0(rSideUnitPos,t1,tMax);
*barycentric1 = S3L_interpolateFrom0(lSideUnitPos,t2,tMax);
// TODO: try to do this with stepping and S3L_LERP_QUALITY
*barycentric0 =
S3L_interpolateFrom0(rSideUnitPos >> S3L_LERP_QUALITY,t1,tMax);
*barycentric1 =
S3L_interpolateFrom0(lSideUnitPos >> S3L_LERP_QUALITY,t2,tMax);
*barycentric2 = S3L_FRACTIONS_PER_UNIT - *barycentric0 - *barycentric1;
p.x = x;