diff options
Diffstat (limited to 'clip.c')
| -rw-r--r-- | clip.c | 35 |
1 files changed, 25 insertions, 10 deletions
@@ -53,6 +53,21 @@ cleanpoly(Polygon *p) p->n = 0; } +static void +fprintpoly(int fd, Polygon *p) +{ + int i; + + for(i = 0; i < p->n; i++) + fprint(fd, "%d/%lud p %V\n", i, p->n, p->v[i].p); +} + +static int +eqpt3(Point3 a, Point3 b) +{ + return vec3len(subpt3(a, b)) < 1e-6; +} + /* * references: * - James F. Blinn, Martin E. Newell, “Clipping Using Homogeneous Coordinates”, @@ -76,9 +91,9 @@ clipprimitive(Primitive *p) double d0, d1, perc; Polygon Vin, Vout; Vertex *v0, *v1, v; /* edge verts and new vertex (line-plane intersection) */ - int i, j, nt; + int i, j, np; - nt = 0; + np = 0; memset(&Vin, 0, sizeof Vin); memset(&Vout, 0, sizeof Vout); for(i = 0; i < p[0].type+1; i++) @@ -119,30 +134,30 @@ allin: cleanpoly(&Vout); else switch(p[0].type){ case PLine: - /* TODO fix line clipping (they disappear instead, why?) */ p[0].v[0] = dupvertex(&Vout.v[0]); - p[0].v[1] = dupvertex(&Vout.v[1]); + p[0].v[1] = eqpt3(Vout.v[0].p, Vout.v[1].p)? dupvertex(&Vout.v[2]): dupvertex(&Vout.v[1]); cleanpoly(&Vout); + np = 1; break; case PTriangle: /* triangulate */ - for(i = 0; i < Vout.n-2; i++, nt++){ + for(i = 0; i < Vout.n-2; i++, np++){ /* * when performing fan triangulation, indices 0 and 2 * are referenced on every triangle, so duplicate them * to avoid complications during rasterization. */ - memmove(&p[nt], &p[0], sizeof *p); - p[nt].v[0] = i < Vout.n-2-1? dupvertex(&Vout.v[0]): Vout.v[0]; - p[nt].v[1] = Vout.v[i+1]; - p[nt].v[2] = i < Vout.n-2-1? dupvertex(&Vout.v[i+2]): Vout.v[i+2]; + memmove(&p[np], &p[0], sizeof *p); + p[np].v[0] = i < Vout.n-2-1? dupvertex(&Vout.v[0]): Vout.v[0]; + p[np].v[1] = Vout.v[i+1]; + p[np].v[2] = i < Vout.n-2-1? dupvertex(&Vout.v[i+2]): Vout.v[i+2]; } break; } free(Vout.v); free(Vin.v); - return nt; + return np; } static int |