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Add fast ler state

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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; int16_t minorDiff;
} S3L_BresenhamState; ///< State of drawing a line with Bresenham algorithm. } 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 typedef struct
{ {
S3L_ScreenCoord p0[2]; ///< 2D coordinates of the 1st point projection 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 lErrAdd, rErrAdd, // error value to add in each Bresenham cycle
lErrSub, rErrSub; // error value to substract when moving in x direction lErrSub, rErrSub; // error value to substract when moving in x direction
S3L_Unit S3L_FastLerpState
lSideStep, rSideStep, lSideUnitPosScaled, rSideUnitPosScaled; lSideFLS, rSideFLS;
/* ^ 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. */
/* init side for the algorithm, params: /* init side for the algorithm, params:
s - which side (l or r) s - which side (l or r)
@ -1213,13 +1222,13 @@ void _S3L_drawFilledTriangle(
s##X = p1##PointSx;\ s##X = p1##PointSx;\
s##Dx = p2##PointSx - p1##PointSx;\ s##Dx = p2##PointSx - p1##PointSx;\
s##Dy = p2##PointSy - p1##PointSy;\ 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##Dy != 0 ? s##Dy : 1);\
s##SideUnitPosScaled = 0;\ s##SideFLS.valueScaled = 0;\
if (!down)\ if (!down)\
{\ {\
s##SideUnitPosScaled = S3L_FRACTIONS_PER_UNIT << S3L_FAST_LERP_QUALITY;\ s##SideFLS.valueScaled = S3L_FRACTIONS_PER_UNIT << S3L_FAST_LERP_QUALITY;\
s##SideStep *= -1;\ s##SideFLS.stepScaled *= -1;\
}\ }\
s##Inc = s##Dx >= 0 ? 1 : -1;\ s##Inc = s##Dx >= 0 ? 1 : -1;\
if (s##Dx < 0)\ if (s##Dx < 0)\
@ -1277,9 +1286,9 @@ void _S3L_drawFilledTriangle(
S3L_Unit *tmp = barycentric##b0;\ S3L_Unit *tmp = barycentric##b0;\
barycentric##b0 = barycentric##b1;\ barycentric##b0 = barycentric##b1;\
barycentric##b1 = tmp;\ barycentric##b1 = tmp;\
s##SideUnitPosScaled = (S3L_FRACTIONS_PER_UNIT\ s##SideFLS.valueScaled = (S3L_FRACTIONS_PER_UNIT\
<< S3L_FAST_LERP_QUALITY) - s##SideUnitPosScaled;\ << S3L_FAST_LERP_QUALITY) - s##SideFLS.valueScaled;\
s##SideStep *= -1; s##SideFLS.stepScaled *= -1;
if (splitOnLeft) if (splitOnLeft)
{ {
@ -1322,11 +1331,8 @@ void _S3L_drawFilledTriangle(
lDepth, rDepth, lDepth, rDepth,
lT, rT; // perspective-corrected position along either side lT, rT; // perspective-corrected position along either side
lT = S3L_correctPerspective(lSideUnitPosScaled >> S3L_FAST_LERP_QUALITY, lT = S3L_correctPerspective(S3L_getFastLerpValue(lSideFLS),&lPC);
&lPC); rT = S3L_correctPerspective(S3L_getFastLerpValue(rSideFLS),&rPC);
rT = S3L_correctPerspective(rSideUnitPosScaled >> S3L_FAST_LERP_QUALITY,
&rPC);
lDepth = S3L_interpolateByUnit(lPC.a[2],lPC.b[2],lT); lDepth = S3L_interpolateByUnit(lPC.a[2],lPC.b[2],lT);
rDepth = S3L_interpolateByUnit(rPC.a[2],rPC.b[2],rT); rDepth = S3L_interpolateByUnit(rPC.a[2],rPC.b[2],rT);
@ -1342,11 +1348,13 @@ void _S3L_drawFilledTriangle(
&rowPC &rowPC
); );
#else #else
S3L_Unit b0 = 0; S3L_FastLerpState b0FLS, b1FLS;
S3L_Unit b1 = lSideUnitPosScaled;
S3L_Unit b0Step = rSideUnitPosScaled / rowLength; b0FLS.valueScaled = 0;
S3L_Unit b1Step = lSideUnitPosScaled / rowLength; b1FLS.valueScaled = lSideFLS.valueScaled;
b0FLS.stepScaled = rSideFLS.valueScaled / rowLength;
b1FLS.stepScaled = -1 * lSideFLS.valueScaled / rowLength;
#endif #endif
// clip to the screen in x dimension: // clip to the screen in x dimension:
@ -1359,8 +1367,8 @@ void _S3L_drawFilledTriangle(
lXClipped = 0; lXClipped = 0;
#if S3L_PERSPECTIVE_CORRECTION != 1 #if S3L_PERSPECTIVE_CORRECTION != 1
b0 -= lX * b0Step; b0FLS.valueScaled -= lX * b0FLS.stepScaled;
b1 += lX * b1Step; b1FLS.valueScaled -= lX * b1FLS.stepScaled;
#endif #endif
} }
@ -1380,11 +1388,11 @@ void _S3L_drawFilledTriangle(
*barycentric1 = *barycentric1 =
S3L_interpolateByUnitFrom0(lT,S3L_FRACTIONS_PER_UNIT - rowT); S3L_interpolateByUnitFrom0(lT,S3L_FRACTIONS_PER_UNIT - rowT);
#else #else
*barycentric0 = b0 >> S3L_FAST_LERP_QUALITY; *barycentric0 = S3L_getFastLerpValue(b0FLS);
*barycentric1 = b1 >> S3L_FAST_LERP_QUALITY; *barycentric1 = S3L_getFastLerpValue(b1FLS);
b0 += b0Step; S3L_stepFastLerp(b0FLS);
b1 -= b1Step; S3L_stepFastLerp(b1FLS);
#endif #endif
*barycentric2 = S3L_FRACTIONS_PER_UNIT - *barycentric0 - *barycentric1; *barycentric2 = S3L_FRACTIONS_PER_UNIT - *barycentric0 - *barycentric1;
@ -1394,8 +1402,8 @@ void _S3L_drawFilledTriangle(
} }
} // y clipping } // y clipping
lSideUnitPosScaled += lSideStep; S3L_stepFastLerp(lSideFLS);
rSideUnitPosScaled += rSideStep; S3L_stepFastLerp(rSideFLS);
++currentY; ++currentY;
} }