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Continue fixing rasterization

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This commit is contained in:
Miloslav Číž 2019-05-04 16:57:10 +02:00
parent e5425af9ed
commit 42eaf3d8e8
1 changed files with 26 additions and 29 deletions
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55
s3l.h
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@ -786,43 +786,40 @@ void S3L_drawTriangle(
lSideUnitStep, rSideUnitStep,
lSideUnitPos, rSideUnitPos;
int16_t helperDxAbs;
/* init side for the algorithm, params:
v - which side (l or r)
s - which side (l or r)
p1 - point from (t, l or r)
p2 - point to (t, l or r)
down - whether the side coordinate goes top-down or vice versa
shift - initial shift of the line, to rasterize pix. centers */
#define initSide(v,p1,p2,down,shift)\
v##X = p1##PointX;\
v##Dx = p2##PointX - p1##PointX;\
v##Dy = p2##PointY - p1##PointY;\
v##SideUnitStep = S3L_FRACTIONS_PER_UNIT / (v##Dy != 0 ? v##Dy : 1);\
v##SideUnitPos = 0;\
left - whether to rasterize on left of the line or vice versa */
#define initSide(s,p1,p2,down,left)\
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##SideUnitPos = 0;\
if (!down)\
{\
v##SideUnitPos = S3L_FRACTIONS_PER_UNIT;\
v##SideUnitStep *= -1;\
s##SideUnitPos = S3L_FRACTIONS_PER_UNIT;\
s##SideUnitStep *= -1;\
}\
helperDxAbs = S3L_abs(v##Dx);\
v##Inc = v##Dx >= 0 ? 1 : -1;\
v##Err = (2 + shift) * helperDxAbs - v##Dy;\
v##ErrAdd = 2 * helperDxAbs;\
v##ErrSub = 2 * v##Dy;\
v##ErrSub = v##ErrSub != 0 ? v##ErrSub : 1; /* don't allow 0, could lead
to an infinite substracting
loop */
s##Inc = s##Dx >= 0 ? 1 : -1;\
s##Err = left != (s##Dx < 0) ? 0 : s##Dy;\
s##ErrAdd = S3L_abs(s##Dx);\
s##ErrSub = s##Dy != 0 ? s##Dy : 1; /* don't allow 0, could lead to an
infinite substracting loop */
#define stepSide(s)\
while (s##Err > 0)\
while (s##Err > s##Dy)\
{\
s##X += s##Inc;\
s##Err -= s##ErrSub;\
}\
s##Err += s##ErrAdd;
initSide(r,t,r,1,-1)
initSide(l,t,l,1,1)
initSide(r,t,r,1,1)
initSide(l,t,l,1,0)
while (currentY <= endY) // draw the triangle from top to bottom
{
@ -830,7 +827,7 @@ void S3L_drawTriangle(
{ // then reinit one side
if (splitOnLeft)
{
initSide(l,l,r,0,1);
initSide(l,l,r,0,0);
S3L_Unit *tmp = barycentric0;
barycentric0 = barycentric2;
@ -841,7 +838,7 @@ void S3L_drawTriangle(
}
else
{
initSide(r,r,l,0,-1);
initSide(r,r,l,0,1);
S3L_Unit *tmp = barycentric1;
barycentric1 = barycentric2;
@ -852,6 +849,9 @@ void S3L_drawTriangle(
}
}
stepSide(r)
stepSide(l)
p.y = currentY;
// draw the horizontal line
@ -862,7 +862,7 @@ void S3L_drawTriangle(
S3L_Unit t1 = 0;
S3L_Unit t2 = tMax;
for (S3L_ScreenCoord x = lX; x < rX; ++x)
for (S3L_ScreenCoord x = lX; x <= rX; ++x)
{
*barycentric0 = S3L_interpolateFrom0(rSideUnitPos,t1,tMax);
*barycentric1 = S3L_interpolateFrom0(lSideUnitPos,t2,tMax);
@ -875,9 +875,6 @@ void S3L_drawTriangle(
--t2;
}
stepSide(r)
stepSide(l)
lSideUnitPos += lSideUnitStep;
rSideUnitPos += rSideUnitStep;