From d2cbc9f1425fd246a780d5b29ec1d1aacc979bf3 Mon Sep 17 00:00:00 2001 From: Trammell Hudson Date: Sun, 15 Feb 2015 14:20:48 -0500 Subject: [PATCH] inset circles work! --- faces.c | 187 +++++++++++++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 178 insertions(+), 9 deletions(-) diff --git a/faces.c b/faces.c index accc3d9..7d66922 100644 --- a/faces.c +++ b/faces.c @@ -14,7 +14,7 @@ #include "stl_3d.h" static const char * stroke_string - = "stroke=\"#FF0000\" stroke-width=\"1px\" fill=\"none\""; + = "stroke-width=\"1px\" fill=\"none\""; typedef struct { @@ -58,10 +58,30 @@ svg_line( v3_project(ref, p1, &x1, &y1); v3_project(ref, p2, &x2, &y2); + const char * color = "#FF0000"; - printf("\n", + printf("\n", x1, y1, x2, y2, + color, + stroke_string + ); +} + + +static void +svg_circle( + const double x, + const double y, + const double rad, + const char * const color +) +{ + printf("\n", + x, + y, + rad, + color, stroke_string ); } @@ -82,9 +102,6 @@ trace_face( int i = 0; int vertex_count = 0; - // preload the list with the starting point - vertex_list[vertex_count++] = f->vertex[i]; - do { const stl_vertex_t * const v1 = f->vertex[(i+0) % 3]; const stl_vertex_t * const v2 = f->vertex[(i+1) % 3]; @@ -127,6 +144,140 @@ trace_face( return vertex_count; } +// 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 main(void) @@ -134,8 +285,8 @@ main(void) stl_3d_t * const stl = stl_3d_parse(STDIN_FILENO); if (!stl) return EXIT_FAILURE; - const double inset = 8; - const double hole = 3; + const double inset_distance = 8; + const double hole_radius = 3; int * const face_used = calloc(sizeof(*face_used), stl->num_face); @@ -170,8 +321,26 @@ main(void) printf("\n", i); - for (int j = 0 ; j < vertex_count-1 ; j++) - svg_line(&ref, vertex_list[j]->p, vertex_list[j+1]->p); + // generate the polygon outline (should be one path?) + for (int j = 0 ; j < vertex_count ; j++) + svg_line( + &ref, + vertex_list[(j+0) % vertex_count]->p, + vertex_list[(j+1) % vertex_count]->p + ); + + // generate the inset mounting holes + for (int j = 0 ; j < vertex_count ; j++) + { + double x, y; + inset(&ref, inset_distance, &x, &y, + vertex_list[(j+0) % vertex_count]->p, + vertex_list[(j+1) % vertex_count]->p, + vertex_list[(j+2) % vertex_count]->p + ); + svg_circle(x, y, hole_radius, "#00ff00"); + } + printf("\n"); }