📄 arctess.cc
字号:
if( s1 == s2 )
if( t1 < t2 )
pwl_right( arc, s1, t1, t2, stepsize );
else
pwl_left( arc, s1, t1, t2, stepsize );
else if( t1 == t2 )
if( s1 < s2 )
pwl_bottom( arc, t1, s1, s2, stepsize );
else
pwl_top( arc, t1, s1, s2, stepsize );
else
pwl( arc, s1, s2, t1, t2, stepsize );
}
/*-----------------------------------------------------------------------------
* tessellateNonlinear - constuct a nonlinear pwl arc and attach it to an Arc
*-----------------------------------------------------------------------------
*/
void
ArcTessellator::tessellateNonlinear( Arc *arc, REAL geo_stepsize, REAL arc_stepsize, int isrational )
{
assert( arc->pwlArc == NULL );
REAL stepsize = geo_stepsize * arc_stepsize;
BezierArc *bezierArc = arc->bezierArc;
REAL size; //bounding box size of the curve in UV
{
int i,j;
REAL min_u, min_v, max_u,max_v;
min_u = max_u = bezierArc->cpts[0];
min_v = max_v = bezierArc->cpts[1];
for(i=1, j=2; i<bezierArc->order; i++, j+= bezierArc->stride)
{
if(bezierArc->cpts[j] < min_u)
min_u = bezierArc->cpts[j];
if(bezierArc->cpts[j] > max_u)
max_u = bezierArc->cpts[j];
if(bezierArc->cpts[j+1] < min_v)
min_v = bezierArc->cpts[j+1];
if(bezierArc->cpts[j+1] > max_v)
max_v = bezierArc->cpts[j+1];
}
size = max_u - min_u;
if(size < max_v - min_v)
size = max_v - min_v;
}
/*int nsteps = 1 + (int) (1.0/stepsize);*/
int nsteps = (int) (size/stepsize);
if(nsteps <=0)
nsteps=1;
TrimVertex *vert = trimvertexpool.get( nsteps+1 );
REAL dp = 1.0/nsteps;
arc->pwlArc = new(pwlarcpool) PwlArc();
arc->pwlArc->pts = vert;
if( isrational ) {
REAL pow_u[MAXORDER], pow_v[MAXORDER], pow_w[MAXORDER];
trim_power_coeffs( bezierArc, pow_u, 0 );
trim_power_coeffs( bezierArc, pow_v, 1 );
trim_power_coeffs( bezierArc, pow_w, 2 );
/* compute first point exactly */
REAL *b = bezierArc->cpts;
vert->param[0] = b[0]/b[2];
vert->param[1] = b[1]/b[2];
/* strength reduction on p = dp * step would introduce error */
int step;
register long order = bezierArc->order;
for( step=1, ++vert; step<nsteps; step++, vert++ ) {
register REAL p = dp * step;
register REAL u = pow_u[0];
register REAL v = pow_v[0];
register REAL w = pow_w[0];
for( register int i = 1; i < order; i++ ) {
u = u * p + pow_u[i];
v = v * p + pow_v[i];
w = w * p + pow_w[i];
}
vert->param[0] = u/w;
vert->param[1] = v/w;
#ifndef NOELIMINATION
REAL ds = glu_abs(vert[0].param[0] - vert[-1].param[0]);
REAL dt = glu_abs(vert[0].param[1] - vert[-1].param[1]);
int canremove = (ds<geo_stepsize && dt<geo_stepsize) ? 1 : 0;
REAL ods=0.0, odt=0.0;
if( ocanremove && canremove ) {
REAL nds = ds + ods;
REAL ndt = dt + odt;
if( nds<geo_stepsize && ndt<geo_stepsize ) {
// remove previous point
--vert;
vert[0].param[0] = vert[1].param[0];
vert[0].param[1] = vert[1].param[1];
ods = nds;
odt = ndt;
ocanremove = 1;
} else {
ocanremove = canremove;
ods = ds;
odt = dt;
}
} else {
ocanremove = canremove;
ods = ds;
odt = dt;
}
#endif
}
/* compute last point exactly */
b += (order - 1) * bezierArc->stride;
vert->param[0] = b[0]/b[2];
vert->param[1] = b[1]/b[2];
} else {
REAL pow_u[MAXORDER], pow_v[MAXORDER];
trim_power_coeffs( bezierArc, pow_u, 0 );
trim_power_coeffs( bezierArc, pow_v, 1 );
/* compute first point exactly */
REAL *b = bezierArc->cpts;
vert->param[0] = b[0];
vert->param[1] = b[1];
/* strength reduction on p = dp * step would introduce error */
int step;
register long order = bezierArc->order;
for( step=1, ++vert; step<nsteps; step++, vert++ ) {
register REAL p = dp * step;
register REAL u = pow_u[0];
register REAL v = pow_v[0];
for( register int i = 1; i < bezierArc->order; i++ ) {
u = u * p + pow_u[i];
v = v * p + pow_v[i];
}
vert->param[0] = u;
vert->param[1] = v;
#ifndef NOELIMINATION
REAL ds = glu_abs(vert[0].param[0] - vert[-1].param[0]);
REAL dt = glu_abs(vert[0].param[1] - vert[-1].param[1]);
int canremove = (ds<geo_stepsize && dt<geo_stepsize) ? 1 : 0;
REAL ods=0.0, odt=0.0;
if( ocanremove && canremove ) {
REAL nds = ds + ods;
REAL ndt = dt + odt;
if( nds<geo_stepsize && ndt<geo_stepsize ) {
// remove previous point
--vert;
vert[0].param[0] = vert[1].param[0];
vert[0].param[1] = vert[1].param[1];
ods = nds;
odt = ndt;
ocanremove = 1;
} else {
ocanremove = canremove;
ods = ds;
odt = dt;
}
} else {
ocanremove = canremove;
ods = ds;
odt = dt;
}
#endif
}
/* compute last point exactly */
b += (order - 1) * bezierArc->stride;
vert->param[0] = b[0];
vert->param[1] = b[1];
}
arc->pwlArc->npts = vert - arc->pwlArc->pts + 1;
/*
for( TrimVertex *vt=pwlArc->pts; vt != vert-1; vt++ ) {
if( tooclose( vt[0].param[0], vt[1].param[0] ) )
vt[1].param[0] = vt[0].param[0];
if( tooclose( vt[0].param[1], vt[1].param[1] ) )
vt[1].param[1] = vt[0].param[1];
}
*/
}
const REAL ArcTessellator::gl_Bernstein[][MAXORDER][MAXORDER] = {
{
{1, 0, 0, 0, 0, 0, 0, 0 },
{0, 0, 0, 0, 0, 0, 0, 0 },
{0, 0, 0, 0, 0, 0, 0, 0 },
{0, 0, 0, 0, 0, 0, 0, 0 },
{0, 0, 0, 0, 0, 0, 0, 0 },
{0, 0, 0, 0, 0, 0, 0, 0 },
{0, 0, 0, 0, 0, 0, 0, 0 },
{0, 0, 0, 0, 0, 0, 0, 0 }
},
{
{-1, 1, 0, 0, 0, 0, 0, 0 },
{1, 0, 0, 0, 0, 0, 0, 0 },
{0, 0, 0, 0, 0, 0, 0, 0 },
{0, 0, 0, 0, 0, 0, 0, 0 },
{0, 0, 0, 0, 0, 0, 0, 0 },
{0, 0, 0, 0, 0, 0, 0, 0 },
{0, 0, 0, 0, 0, 0, 0, 0 },
{0, 0, 0, 0, 0, 0, 0, 0 }
},
{
{1, -2, 1, 0, 0, 0, 0, 0 },
{-2, 2, 0, 0, 0, 0, 0, 0 },
{1, 0, 0, 0, 0, 0, 0, 0 },
{0, 0, 0, 0, 0, 0, 0, 0 },
{0, 0, 0, 0, 0, 0, 0, 0 },
{0, 0, 0, 0, 0, 0, 0, 0 },
{0, 0, 0, 0, 0, 0, 0, 0 },
{0, 0, 0, 0, 0, 0, 0, 0 }
},
{
{-1, 3, -3, 1, 0, 0, 0, 0 },
{3, -6, 3, 0, 0, 0, 0, 0 },
{-3, 3, 0, 0, 0, 0, 0, 0 },
{1, 0, 0, 0, 0, 0, 0, 0 },
{0, 0, 0, 0, 0, 0, 0, 0 },
{0, 0, 0, 0, 0, 0, 0, 0 },
{0, 0, 0, 0, 0, 0, 0, 0 },
{0, 0, 0, 0, 0, 0, 0, 0 }
},
{
{1, -4, 6, -4, 1, 0, 0, 0 },
{-4, 12, -12, 4, 0, 0, 0, 0 },
{6, -12, 6, 0, 0, 0, 0, 0 },
{-4, 4, 0, 0, 0, 0, 0, 0 },
{1, 0, 0, 0, 0, 0, 0, 0 },
{0, 0, 0, 0, 0, 0, 0, 0 },
{0, 0, 0, 0, 0, 0, 0, 0 },
{0, 0, 0, 0, 0, 0, 0, 0 }
},
{
{-1, 5, -10, 10, -5, 1, 0, 0 },
{5, -20, 30, -20, 5, 0, 0, 0 },
{-10, 30, -30, 10, 0, 0, 0, 0 },
{10, -20, 10, 0, 0, 0, 0, 0 },
{-5, 5, 0, 0, 0, 0, 0, 0 },
{1, 0, 0, 0, 0, 0, 0, 0 },
{0, 0, 0, 0, 0, 0, 0, 0 },
{0, 0, 0, 0, 0, 0, 0, 0 }
},
{
{1, -6, 15, -20, 15, -6, 1, 0 },
{-6, 30, -60, 60, -30, 6, 0, 0 },
{15, -60, 90, -60, 15, 0, 0, 0 },
{-20, 60, -60, 20, 0, 0, 0, 0 },
{15, -30, 15, 0, 0, 0, 0, 0 },
{-6, 6, 0, 0, 0, 0, 0, 0 },
{1, 0, 0, 0, 0, 0, 0, 0 },
{0, 0, 0, 0, 0, 0, 0, 0 }
},
{
{-1, 7, -21, 35, -35, 21, -7, 1 },
{7, -42, 105, -140, 105, -42, 7, 0 },
{-21, 105, -210, 210, -105, 21, 0, 0 },
{35, -140, 210, -140, 35, 0, 0, 0 },
{-35, 105, -105, 35, 0, 0, 0, 0 },
{21, -42, 21, 0, 0, 0, 0, 0 },
{-7, 7, 0, 0, 0, 0, 0, 0 },
{1, 0, 0, 0, 0, 0, 0, 0 }
}};
/*-----------------------------------------------------------------------------
* trim_power_coeffs - compute power basis coefficients from bezier coeffients
*-----------------------------------------------------------------------------
*/
void
ArcTessellator::trim_power_coeffs( BezierArc *bez_arc, REAL *p, int coord )
{
register int stride = bez_arc->stride;
register int order = bez_arc->order;
register REAL *base = bez_arc->cpts + coord;
REAL const (*mat)[MAXORDER][MAXORDER] = &gl_Bernstein[order-1];
REAL const (*lrow)[MAXORDER] = &(*mat)[order];
/* WIN32 didn't like the following line within the for-loop */
REAL const (*row)[MAXORDER] = &(*mat)[0];
for( ; row != lrow; row++ ) {
register REAL s = 0.0;
register REAL *point = base;
register REAL const *mlast = *row + order;
for( REAL const *m = *row; m != mlast; m++, point += stride )
s += *(m) * (*point);
*(p++) = s;
}
}
⌨️ 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 + -