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Add fast ler state

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This commit is contained in:
Miloslav Číž 2019-05-20 22:48:57 +02:00
parent 4784993e63
commit aba0c82426
1 changed files with 37 additions and 29 deletions
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66
s3l.h
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@ -883,6 +883,18 @@ typedef struct
int16_t minorDiff;
} S3L_BresenhamState; ///< State of drawing a line with Bresenham algorithm.
typedef struct
{
S3L_Unit valueScaled;
S3L_Unit stepScaled;
} S3L_FastLerpState;
#define S3L_getFastLerpValue(state)\
(state.valueScaled >> S3L_FAST_LERP_QUALITY)
#define S3L_stepFastLerp(state)\
state.valueScaled += state.stepScaled
typedef struct
{
S3L_ScreenCoord p0[2]; ///< 2D coordinates of the 1st point projection
@ -1198,11 +1210,8 @@ void _S3L_drawFilledTriangle(
lErrAdd, rErrAdd, // error value to add in each Bresenham cycle
lErrSub, rErrSub; // error value to substract when moving in x direction
S3L_Unit
lSideStep, rSideStep, lSideUnitPosScaled, rSideUnitPosScaled;
/* ^ These are helper vars for faster linear iterpolation (we scale the
S3L_FRACTIONS_PER_UNIT up by shifting to the right by
S3L_FAST_LERP_QUALITY and simply increment by steps. */
S3L_FastLerpState
lSideFLS, rSideFLS;
/* init side for the algorithm, params:
s - which side (l or r)
@ -1213,13 +1222,13 @@ void _S3L_drawFilledTriangle(
s##X = p1##PointSx;\
s##Dx = p2##PointSx - p1##PointSx;\
s##Dy = p2##PointSy - p1##PointSy;\
s##SideStep = (S3L_FRACTIONS_PER_UNIT << S3L_FAST_LERP_QUALITY)\
s##SideFLS.stepScaled = (S3L_FRACTIONS_PER_UNIT << S3L_FAST_LERP_QUALITY)\
/ (s##Dy != 0 ? s##Dy : 1);\
s##SideUnitPosScaled = 0;\
s##SideFLS.valueScaled = 0;\
if (!down)\
{\
s##SideUnitPosScaled = S3L_FRACTIONS_PER_UNIT << S3L_FAST_LERP_QUALITY;\
s##SideStep *= -1;\
s##SideFLS.valueScaled = S3L_FRACTIONS_PER_UNIT << S3L_FAST_LERP_QUALITY;\
s##SideFLS.stepScaled *= -1;\
}\
s##Inc = s##Dx >= 0 ? 1 : -1;\
if (s##Dx < 0)\
@ -1277,9 +1286,9 @@ void _S3L_drawFilledTriangle(
S3L_Unit *tmp = barycentric##b0;\
barycentric##b0 = barycentric##b1;\
barycentric##b1 = tmp;\
s##SideUnitPosScaled = (S3L_FRACTIONS_PER_UNIT\
<< S3L_FAST_LERP_QUALITY) - s##SideUnitPosScaled;\
s##SideStep *= -1;
s##SideFLS.valueScaled = (S3L_FRACTIONS_PER_UNIT\
<< S3L_FAST_LERP_QUALITY) - s##SideFLS.valueScaled;\
s##SideFLS.stepScaled *= -1;
if (splitOnLeft)
{
@ -1322,11 +1331,8 @@ void _S3L_drawFilledTriangle(
lDepth, rDepth,
lT, rT; // perspective-corrected position along either side
lT = S3L_correctPerspective(lSideUnitPosScaled >> S3L_FAST_LERP_QUALITY,
&lPC);
rT = S3L_correctPerspective(rSideUnitPosScaled >> S3L_FAST_LERP_QUALITY,
&rPC);
lT = S3L_correctPerspective(S3L_getFastLerpValue(lSideFLS),&lPC);
rT = S3L_correctPerspective(S3L_getFastLerpValue(rSideFLS),&rPC);
lDepth = S3L_interpolateByUnit(lPC.a[2],lPC.b[2],lT);
rDepth = S3L_interpolateByUnit(rPC.a[2],rPC.b[2],rT);
@ -1342,11 +1348,13 @@ void _S3L_drawFilledTriangle(
&rowPC
);
#else
S3L_Unit b0 = 0;
S3L_Unit b1 = lSideUnitPosScaled;
S3L_FastLerpState b0FLS, b1FLS;
S3L_Unit b0Step = rSideUnitPosScaled / rowLength;
S3L_Unit b1Step = lSideUnitPosScaled / rowLength;
b0FLS.valueScaled = 0;
b1FLS.valueScaled = lSideFLS.valueScaled;
b0FLS.stepScaled = rSideFLS.valueScaled / rowLength;
b1FLS.stepScaled = -1 * lSideFLS.valueScaled / rowLength;
#endif
// clip to the screen in x dimension:
@ -1359,8 +1367,8 @@ void _S3L_drawFilledTriangle(
lXClipped = 0;
#if S3L_PERSPECTIVE_CORRECTION != 1
b0 -= lX * b0Step;
b1 += lX * b1Step;
b0FLS.valueScaled -= lX * b0FLS.stepScaled;
b1FLS.valueScaled -= lX * b1FLS.stepScaled;
#endif
}
@ -1380,11 +1388,11 @@ void _S3L_drawFilledTriangle(
*barycentric1 =
S3L_interpolateByUnitFrom0(lT,S3L_FRACTIONS_PER_UNIT - rowT);
#else
*barycentric0 = b0 >> S3L_FAST_LERP_QUALITY;
*barycentric1 = b1 >> S3L_FAST_LERP_QUALITY;
*barycentric0 = S3L_getFastLerpValue(b0FLS);
*barycentric1 = S3L_getFastLerpValue(b1FLS);
b0 += b0Step;
b1 -= b1Step;
S3L_stepFastLerp(b0FLS);
S3L_stepFastLerp(b1FLS);
#endif
*barycentric2 = S3L_FRACTIONS_PER_UNIT - *barycentric0 - *barycentric1;
@ -1394,8 +1402,8 @@ void _S3L_drawFilledTriangle(
}
} // y clipping
lSideUnitPosScaled += lSideStep;
rSideUnitPosScaled += rSideStep;
S3L_stepFastLerp(lSideFLS);
S3L_stepFastLerp(rSideFLS);
++currentY;
}