ref: 17ebe55031ae6945ad1f671b69267a672328e4b1
dir: /sys/src/cmd/plot/libplot/vec.c/
#include "mplot.h" #define code(x, y) ((x<clipminx?1:x>clipmaxx?2:0)|(y<clipminy?4:y>clipmaxy?8:0)) void vec(double xx, double yy){ int x0, y0, x1, y1, c0, c1, c, tx, ty; double t; t=SCX(e1->copyx); if(fabs(t)>BIGINT) return; x0=t; t=SCY(e1->copyy); if(fabs(t)>BIGINT) return; y0=t; t=SCX(xx); if(fabs(t)>BIGINT) return; x1=t; t=SCY(yy); if(fabs(t)>BIGINT) return; y1=t; e1->copyx=xx; e1->copyy=yy; /* clipping -- what a concept */ c0=code(x0, y0); c1=code(x1, y1); while(c0|c1){ if(c0&c1) return; c=c0?c0:c1; if(c&1) ty=y0+(y1-y0)*(clipminx-x0)/(x1-x0), tx=clipminx; else if(c&2) ty=y0+(y1-y0)*(clipmaxx-x0)/(x1-x0), tx=clipmaxx; else if(c&4) tx=x0+(x1-x0)*(clipminy-y0)/(y1-y0), ty=clipminy; else tx=x0+(x1-x0)*(clipmaxy-y0)/(y1-y0), ty=clipmaxy; if(c==c0) x0=tx, y0=ty, c0=code(x0, y0); else x1=tx, y1=ty, c1=code(x1, y1); } m_vector(x0, y0, x1, y1, e1->foregr); }