📄 ftraster.c
字号:
if ( ras.fresh )
{
ras.cProfile->start = e1;
ras.fresh = FALSE;
}
size = e2 - e1 + 1;
if ( ras.top + size >= ras.maxBuff )
{
ras.error = Raster_Err_Overflow;
return FAILURE;
}
if ( Dx > 0 )
{
Ix = ( ras.precision * Dx ) / Dy;
Rx = ( ras.precision * Dx ) % Dy;
Dx = 1;
}
else
{
Ix = -( ( ras.precision * -Dx ) / Dy );
Rx = ( ras.precision * -Dx ) % Dy;
Dx = -1;
}
Ax = -Dy;
top = ras.top;
while ( size > 0 )
{
*top++ = x1;
x1 += Ix;
Ax += Rx;
if ( Ax >= 0 )
{
Ax -= Dy;
x1 += Dx;
}
size--;
}
ras.top = top;
return SUCCESS;
}
/*************************************************************************/
/* */
/* <Function> */
/* Line_Down */
/* */
/* <Description> */
/* Computes the x-coordinates of an descending line segment and */
/* stores them in the render pool. */
/* */
/* <Input> */
/* x1 :: The x-coordinate of the segment's start point. */
/* */
/* y1 :: The y-coordinate of the segment's start point. */
/* */
/* x2 :: The x-coordinate of the segment's end point. */
/* */
/* y2 :: The y-coordinate of the segment's end point. */
/* */
/* miny :: A lower vertical clipping bound value. */
/* */
/* maxy :: An upper vertical clipping bound value. */
/* */
/* <Return> */
/* SUCCESS on success, FAILURE on render pool overflow. */
/* */
static Bool
Line_Down( RAS_ARGS Long x1,
Long y1,
Long x2,
Long y2,
Long miny,
Long maxy )
{
Bool result, fresh;
fresh = ras.fresh;
result = Line_Up( RAS_VARS x1, -y1, x2, -y2, -maxy, -miny );
if ( fresh && !ras.fresh )
ras.cProfile->start = -ras.cProfile->start;
return result;
}
/* A function type describing the functions used to split Bezier arcs */
typedef void (*TSplitter)( TPoint* base );
/*************************************************************************/
/* */
/* <Function> */
/* Bezier_Up */
/* */
/* <Description> */
/* Computes the x-coordinates of an ascending Bezier arc and stores */
/* them in the render pool. */
/* */
/* <Input> */
/* degree :: The degree of the Bezier arc (either 2 or 3). */
/* */
/* splitter :: The function to split Bezier arcs. */
/* */
/* miny :: A lower vertical clipping bound value. */
/* */
/* maxy :: An upper vertical clipping bound value. */
/* */
/* <Return> */
/* SUCCESS on success, FAILURE on render pool overflow. */
/* */
static Bool
Bezier_Up( RAS_ARGS Int degree,
TSplitter splitter,
Long miny,
Long maxy )
{
Long y1, y2, e, e2, e0;
Short f1;
TPoint* arc;
TPoint* start_arc;
PLong top;
arc = ras.arc;
y1 = arc[degree].y;
y2 = arc[0].y;
top = ras.top;
if ( y2 < miny || y1 > maxy )
goto Fin;
e2 = FLOOR( y2 );
if ( e2 > maxy )
e2 = maxy;
e0 = miny;
if ( y1 < miny )
e = miny;
else
{
e = CEILING( y1 );
f1 = (Short)( FRAC( y1 ) );
e0 = e;
if ( f1 == 0 )
{
if ( ras.joint )
{
top--;
ras.joint = FALSE;
}
*top++ = arc[degree].x;
e += ras.precision;
}
}
if ( ras.fresh )
{
ras.cProfile->start = TRUNC( e0 );
ras.fresh = FALSE;
}
if ( e2 < e )
goto Fin;
if ( ( top + TRUNC( e2 - e ) + 1 ) >= ras.maxBuff )
{
ras.top = top;
ras.error = Raster_Err_Overflow;
return FAILURE;
}
start_arc = arc;
while ( arc >= start_arc && e <= e2 )
{
ras.joint = FALSE;
y2 = arc[0].y;
if ( y2 > e )
{
y1 = arc[degree].y;
if ( y2 - y1 >= ras.precision_step )
{
splitter( arc );
arc += degree;
}
else
{
*top++ = arc[degree].x + FMulDiv( arc[0].x-arc[degree].x,
e - y1, y2 - y1 );
arc -= degree;
e += ras.precision;
}
}
else
{
if ( y2 == e )
{
ras.joint = TRUE;
*top++ = arc[0].x;
e += ras.precision;
}
arc -= degree;
}
}
Fin:
ras.top = top;
ras.arc -= degree;
return SUCCESS;
}
/*************************************************************************/
/* */
/* <Function> */
/* Bezier_Down */
/* */
/* <Description> */
/* Computes the x-coordinates of an descending Bezier arc and stores */
/* them in the render pool. */
/* */
/* <Input> */
/* degree :: The degree of the Bezier arc (either 2 or 3). */
/* */
/* splitter :: The function to split Bezier arcs. */
/* */
/* miny :: A lower vertical clipping bound value. */
/* */
/* maxy :: An upper vertical clipping bound value. */
/* */
/* <Return> */
/* SUCCESS on success, FAILURE on render pool overflow. */
/* */
static Bool
Bezier_Down( RAS_ARGS Int degree,
TSplitter splitter,
Long miny,
Long maxy )
{
TPoint* arc = ras.arc;
Bool result, fresh;
arc[0].y = -arc[0].y;
arc[1].y = -arc[1].y;
arc[2].y = -arc[2].y;
if ( degree > 2 )
arc[3].y = -arc[3].y;
fresh = ras.fresh;
result = Bezier_Up( RAS_VARS degree, splitter, -maxy, -miny );
if ( fresh && !ras.fresh )
ras.cProfile->start = -ras.cProfile->start;
arc[0].y = -arc[0].y;
return result;
}
/*************************************************************************/
/* */
/* <Function> */
/* Line_To */
/* */
/* <Description> */
/* Injects a new line segment and adjusts Profiles list. */
/* */
/* <Input> */
/* x :: The x-coordinate of the segment's end point (its start point */
/* is stored in `lastX'). */
/* */
/* y :: The y-coordinate of the segment's end point (its start point */
/* is stored in `lastY'). */
/* */
/* <Return> */
/* SUCCESS on success, FAILURE on render pool overflow or incorrect */
/* profile. */
/* */
static Bool
Line_To( RAS_ARGS Long x,
Long y )
{
/* First, detect a change of direction */
switch ( ras.state )
{
case Unknown_State:
if ( y > ras.lastY )
{
if ( New_Profile( RAS_VARS Ascending_State ) )
return FAILURE;
}
else
{
if ( y < ras.lastY )
if ( New_Profile( RAS_VARS Descending_State ) )
return FAILURE;
}
break;
case Ascending_State:
if ( y < ras.lastY )
{
if ( End_Profile( RAS_VAR ) ||
New_Profile( RAS_VARS Descending_State ) )
return FAILURE;
}
break;
case Descending_State:
if ( y > ras.lastY )
{
if ( End_Profile( RAS_VAR ) ||
New_Profile( RAS_VARS Ascending_State ) )
return FAILURE;
}
break;
default:
⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -