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Code Issues 9 Releases Wiki Activity

Optimize Division

This commit is contained in:
Anurag Thakur 2022-10-19 01:50:43 +05:30
parent 467ba66539
commit 108e5e3e34
1 changed files with 27 additions and 9 deletions
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36
src/dense/ftdense.c
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@ -22,6 +22,12 @@
#define UPSCALE( x ) ( ( x ) * ( ONE_PIXEL >> 6 ) )
#define DOWNSCALE( x ) ( ( x ) >> ( PIXEL_BITS - 6 ) )
// TODO: Fix types
#define FT_UDIVPREP( c, b ) \
FT26D6 b ## _r = c ? (FT26D6)0xFFFFFFFF / ( b ) : 0
#define FT_UDIV( a, b ) \
(FT26D6)( ( (FT26D6)( a ) * (FT26D6)( b ## _r ) ) >> 32 )
typedef struct dense_TRaster_
{
void* memory;
@ -119,6 +125,11 @@ dense_render_line( dense_worker* worker, TPos tox, TPos toy )
deltax = to_x - from_x;
deltay = to_y - from_y;
FT_UDIVPREP(from_x != to_x, deltax);
FT_UDIVPREP(from_y != to_y, deltay);
if ( from_y < 0 )
{
from_x -= from_y * deltax/deltay;
@ -187,6 +198,7 @@ dense_render_line( dense_worker* worker, TPos tox, TPos toy )
int y_limit = (to_y + 0x3f)>>6;
FT20D12* m_a = worker->m_a;
for ( int y = y0; y < y_limit; y++ )
{
int linestart = y * worker->m_w;
@ -195,7 +207,8 @@ dense_render_line( dense_worker* worker, TPos tox, TPos toy )
FT26D6 dy = min( (y + 1)<<6, to_y ) - max( y<<6, from_y );
// x coordinate where the line leaves the current scanline
FT26D6 xnext = x + dy * deltax/deltay;
FT26D6 xnext = x + FT_UDIV((dy*deltax), deltay);
// height with sign
FT26D6 d = dy * dir;
@ -235,44 +248,49 @@ dense_render_line( dense_worker* worker, TPos tox, TPos toy )
}
else
{
// total horizontal length of line in current scanline, might be replaced by deltax
FT26D6 oneOverS = x1 - x0;
FT_UDIVPREP(x1 != x0, oneOverS);
FT26D6 x0f = x0 - x0floor;
// 64 - x0f is the horizontal length of line in first pixel
FT26D6 oneMinusX0f = (1<<6) - x0f;
// Stores area of triangle in first pixel divided by d
FT26D6 a0 = ((oneMinusX0f * oneMinusX0f) >> 1) / oneOverS;
FT26D6 a0 = FT_UDIV(((oneMinusX0f * oneMinusX0f) >> 1), oneOverS);
// x1f is the horizontal length in the last pixel
FT26D6 x1f = x1 - x1ceil + (1<<6);
FT26D6 am = ((x1f * x1f) >> 1) / oneOverS;
FT26D6 am = FT_UDIV(((x1f * x1f) >> 1) , oneOverS);
// d * a0 is area of triangle in first pixel
m_a[linestart + x0i] += d * a0;
if ( x1i == x0i + 2 )
m_a[linestart + ( x0i + 1 )] += d * ( (1<<6) - a0 - am );
else
{
FT26D6 a1 = (((1<<6) + (1<<5) - x0f) << 6) / oneOverS;
FT26D6 a1 = FT_UDIV((((1<<6) + (1<<5) - x0f) << 6) , oneOverS);
m_a[linestart + ( x0i + 1 )] += d * ( a1 - a0 );
FT26D6 dTimesS = (d << 12) / oneOverS;
FT26D6 dTimesS = FT_UDIV((d << 12) , oneOverS);
for ( FT26D6 xi = x0i + 2; xi < x1i - 1; xi++ ){
// Increase area for successive pixels by dy/dx
m_a[linestart + xi] += dTimesS;
}
FT26D6 a2 = a1 + (( x1i - x0i - 3 )<<12)/oneOverS;
FT26D6 a2 = a1 + FT_UDIV((( x1i - x0i - 3 )<<12),oneOverS);
m_a[linestart + ( x1i - 1 )] += d * ( (1<<6) - a2 - am );
}
// Area in last pixel of scanline
m_a[linestart + x1i] += d * am;
}
x = xnext;
}
}