move inset into stl_3d

This commit is contained in:
Trammell Hudson 2015-02-15 16:13:32 -05:00
parent a6a08bf10a
commit b5210c4d65
3 changed files with 145 additions and 136 deletions

137
faces.c
View File

@ -57,141 +57,6 @@ svg_circle(
} }
// Determines the intersection point of the line defined by points A and B with the
// line defined by points C and D.
//
// Returns YES if the intersection point was found, and stores that point in X,Y.
// Returns NO if there is no determinable intersection point, in which case X,Y will
// be unmodified.
static int
line_intersect(
double Ax, double Ay,
double Bx, double By,
double Cx, double Cy,
double Dx, double Dy,
double *X, double *Y
)
{
// Fail if either line is undefined.
if ((Ax==Bx && Ay==By) || (Cx==Dx && Cy==Dy))
return 0;
// (1) Translate the system so that point A is on the origin.
Bx-=Ax; By-=Ay;
Cx-=Ax; Cy-=Ay;
Dx-=Ax; Dy-=Ay;
// Discover the length of segment A-B.
const double distAB=sqrt(Bx*Bx+By*By);
// (2) Rotate the system so that point B is on the positive X axis.
const double theCos=Bx/distAB;
const double theSin=By/distAB;
double newX=Cx*theCos+Cy*theSin;
Cy =Cy*theCos-Cx*theSin; Cx=newX;
newX=Dx*theCos+Dy*theSin;
Dy =Dy*theCos-Dx*theSin; Dx=newX;
// Fail if the lines are parallel.
if (Cy==Dy) return 0;
// (3) Discover the position of the intersection point along line A-B.
const double ABpos=Dx+(Cx-Dx)*Dy/(Dy-Cy);
// (4) Apply the discovered position to line A-B in the original coordinate system.
*X=Ax+ABpos*theCos;
*Y=Ay+ABpos*theSin;
return 1;
}
/** Compute the inset coordinate.
* http://alienryderflex.com/polygon_inset/
// Given the sequentially connected points (a,b), (c,d), and (e,f), this
// function returns, in (C,D), a bevel-inset replacement for point (c,d).
//
// Note: If vectors (a,b)->(c,d) and (c,d)->(e,f) are exactly 180° opposed,
// or if either segment is zero-length, this function will do
// nothing; i.e. point (C,D) will not be set.
*/
void
inset(
const refframe_t * const ref,
const double inset_dist,
double * const x_out,
double * const y_out,
const v3_t p0, // previous point
const v3_t p1, // current point to inset
const v3_t p2 // next point
)
{
double a, b, c, d, e, f;
v3_project(ref, p0, &a, &b);
v3_project(ref, p1, &c, &d);
v3_project(ref, p2, &e, &f);
double c1 = c;
double d1 = d;
double c2 = c;
double d2 = d;
// Calculate length of line segments.
const double dx1 = c-a;
const double dy1 = d-b;
const double dist1 = sqrt(dx1*dx1+dy1*dy1);
const double dx2 = e-c;
const double dy2 = f-d;
const double dist2 = sqrt(dx2*dx2+dy2*dy2);
// Exit if either segment is zero-length.
if (dist1==0. || dist2==0.)
{
*x_out = *y_out = 0;
fprintf(stderr, "inset fail\n");
return;
}
// Inset each of the two line segments.
double insetX, insetY;
insetX = dy1/dist1 * inset_dist;
a+=insetX;
c1+=insetX;
insetY = -dx1/dist1 * inset_dist;
b+=insetY;
d1+=insetY;
insetX = dy2/dist2 * inset_dist;
e+=insetX;
c2+=insetX;
insetY = -dx2/dist2 * inset_dist;
f+=insetY;
d2+=insetY;
// If inset segments connect perfectly, return the connection point.
if (c1==c2 && d1==d2)
{
*x_out = c1;
*y_out = d1;
return;
}
// Return the intersection point of the two inset segments (if any).
if (line_intersect(a,b,c1,d1,c2,d2,e,f, x_out, y_out))
return;
*x_out = *y_out = 0;
fprintf(stderr, "inset failed 2\n");
}
int int
main(void) main(void)
{ {
@ -247,7 +112,7 @@ main(void)
for (int j = 0 ; j < vertex_count ; j++) for (int j = 0 ; j < vertex_count ; j++)
{ {
double x, y; double x, y;
inset(&ref, inset_distance, &x, &y, refframe_inset(&ref, inset_distance, &x, &y,
vertex_list[(j+0) % vertex_count]->p, vertex_list[(j+0) % vertex_count]->p,
vertex_list[(j+1) % vertex_count]->p, vertex_list[(j+1) % vertex_count]->p,
vertex_list[(j+2) % vertex_count]->p vertex_list[(j+2) % vertex_count]->p

133
stl_3d.c
View File

@ -335,3 +335,136 @@ v3_project(
} }
// Determines the intersection point of the line defined by points A and B with the
// line defined by points C and D.
//
// Returns YES if the intersection point was found, and stores that point in X,Y.
// Returns NO if there is no determinable intersection point, in which case X,Y will
// be unmodified.
static int
line_intersect(
double Ax, double Ay,
double Bx, double By,
double Cx, double Cy,
double Dx, double Dy,
double *X, double *Y
)
{
// Fail if either line is undefined.
if ((Ax==Bx && Ay==By) || (Cx==Dx && Cy==Dy))
return 0;
// (1) Translate the system so that point A is on the origin.
Bx-=Ax; By-=Ay;
Cx-=Ax; Cy-=Ay;
Dx-=Ax; Dy-=Ay;
// Discover the length of segment A-B.
const double distAB=sqrt(Bx*Bx+By*By);
// (2) Rotate the system so that point B is on the positive X axis.
const double theCos=Bx/distAB;
const double theSin=By/distAB;
double newX=Cx*theCos+Cy*theSin;
Cy =Cy*theCos-Cx*theSin; Cx=newX;
newX=Dx*theCos+Dy*theSin;
Dy =Dy*theCos-Dx*theSin; Dx=newX;
// Fail if the lines are parallel.
if (Cy==Dy) return 0;
// (3) Discover the position of the intersection point along line A-B.
const double ABpos=Dx+(Cx-Dx)*Dy/(Dy-Cy);
// (4) Apply the discovered position to line A-B in the original coordinate system.
*X=Ax+ABpos*theCos;
*Y=Ay+ABpos*theSin;
return 1;
}
/** Compute the inset coordinate.
* http://alienryderflex.com/polygon_inset/
// Given the sequentially connected points (a,b), (c,d), and (e,f), this
// function returns, in (C,D), a bevel-inset replacement for point (c,d).
//
// Note: If vectors (a,b)->(c,d) and (c,d)->(e,f) are exactly 180° opposed,
// or if either segment is zero-length, this function will do
// nothing; i.e. point (C,D) will not be set.
*/
void
refframe_inset(
const refframe_t * const ref,
const double inset_dist,
double * const x_out,
double * const y_out,
const v3_t p0, // previous point
const v3_t p1, // current point to inset
const v3_t p2 // next point
)
{
double a, b, c, d, e, f;
v3_project(ref, p0, &a, &b);
v3_project(ref, p1, &c, &d);
v3_project(ref, p2, &e, &f);
double c1 = c;
double d1 = d;
double c2 = c;
double d2 = d;
// Calculate length of line segments.
const double dx1 = c-a;
const double dy1 = d-b;
const double dist1 = sqrt(dx1*dx1+dy1*dy1);
const double dx2 = e-c;
const double dy2 = f-d;
const double dist2 = sqrt(dx2*dx2+dy2*dy2);
// Exit if either segment is zero-length.
if (dist1==0. || dist2==0.)
{
*x_out = *y_out = 0;
fprintf(stderr, "inset fail\n");
return;
}
// Inset each of the two line segments.
double insetX, insetY;
insetX = dy1/dist1 * inset_dist;
a+=insetX;
c1+=insetX;
insetY = -dx1/dist1 * inset_dist;
b+=insetY;
d1+=insetY;
insetX = dy2/dist2 * inset_dist;
e+=insetX;
c2+=insetX;
insetY = -dx2/dist2 * inset_dist;
f+=insetY;
d2+=insetY;
// If inset segments connect perfectly, return the connection point.
if (c1==c2 && d1==d2)
{
*x_out = c1;
*y_out = d1;
return;
}
// Return the intersection point of the two inset segments (if any).
if (line_intersect(a,b,c1,d1,c2,d2,e,f, x_out, y_out))
return;
*x_out = *y_out = 0;
fprintf(stderr, "inset failed 2\n");
}

View File

@ -82,6 +82,17 @@ refframe_init(
); );
void
refframe_inset(
const refframe_t * const ref,
const double inset_dist,
double * const x_out,
double * const y_out,
const v3_t p0, // previous point
const v3_t p1, // current point to inset
const v3_t p2 // next point
);
/** Project a 3D point onto a 2D space */ /** Project a 3D point onto a 2D space */
void void
v3_project( v3_project(