diff options
Diffstat (limited to 'clip.c')
| -rw-r--r-- | clip.c | 34 |
1 files changed, 31 insertions, 3 deletions
@@ -193,11 +193,37 @@ outcode(Point p, Rectangle r) return code; } +/* lerp vertex attributes to match the new positions */ +void +adjustverts(Point *p0, Point *p1, Vertex *v0, Vertex *v1) +{ + Vertex v[2]; + Point3 dp; + Point Δp; + double len, perc; + + dp = subpt3(v1->p, v0->p); + len = hypot(dp.x, dp.y); + + Δp = subpt(Pt(v0->p.x, v0->p.y), *p0); + perc = len == 0? 0: hypot(Δp.x, Δp.y)/len; + lerpvertex(&v[0], v0, v1, perc); + + Δp = subpt(Pt(v0->p.x, v0->p.y), *p1); + perc = len == 0? 0: hypot(Δp.x, Δp.y)/len; + lerpvertex(&v[1], v0, v1, perc); + + delvattrs(v0); + delvattrs(v1); + *v0 = dupvertex(&v[0]); + *v1 = dupvertex(&v[1]); +} + /* * Cohen-Sutherland rectangle-line clipping */ int -rectclipline(Rectangle r, Point *p0, Point *p1) +rectclipline(Rectangle r, Point *p0, Point *p1, Vertex *v0, Vertex *v1) { int code0, code1; int Δx, Δy; @@ -211,14 +237,16 @@ rectclipline(Rectangle r, Point *p0, Point *p1) code0 = outcode(*p0, r); code1 = outcode(*p1, r); - if(lineisinside(code0, code1)) + if(lineisinside(code0, code1)){ + adjustverts(p0, p1, v0, v1); return 0; - else if(lineisoutside(code0, code1)) + }else if(lineisoutside(code0, code1)) return -1; if(ptisinside(code0)){ swappt(p0, p1); swapi(&code0, &code1); + swapvertex(v0, v1); } if(code0 & CLIPL){ |