12 static int outcode(int x, int y, int xmin, int ymin, int xmax, int ymax)
29 #define FIXMUL(a, b) (((a) * (b)) >> 8)
30 #define FIXDIV(a, b) (((a) << 8) / (b))
32 #define LERP(a, b, t) ((a) + FIXMUL((b) - (a), (t)))
34 int clip_line(int *x0, int *y0, int *x1, int *y1, int xmin, int ymin, int xmax, int ymax)
38 int oc0 = outcode(*x0, *y0, xmin, ymin, xmax, ymax);
39 int oc1 = outcode(*x1, *y1, xmin, ymin, xmax, ymax);
41 long fx0, fy0, fx1, fy1, fxmin, fymin, fxmax, fymax;
43 if(!(oc0 | oc1)) return 1; /* both points are inside */
57 if(oc0 & oc1) return 0; /* both have points with the same outbit, not visible */
58 if(!(oc0 | oc1)) break; /* both points are inside */
60 oc_out = oc0 ? oc0 : oc1;
63 t = FIXDIV(fymin - fy0, fy1 - fy0);
64 x = LERP(fx0, fx1, t);
66 } else if(oc_out & BOTTOM) {
67 t = FIXDIV(fymax - fy0, fy1 - fy0);
68 x = LERP(fx0, fx1, t);
70 } else if(oc_out & LEFT) {
71 t = FIXDIV(fxmin - fx0, fx1 - fx0);
73 y = LERP(fy0, fy1, t);
74 } else if(oc_out & RIGHT) {
75 t = FIXDIV(fxmax - fx0, fx1 - fx0);
77 y = LERP(fy0, fy1, t);
83 oc0 = outcode(fx0 >> 8, fy0 >> 8, xmin, ymin, xmax, ymax);
87 oc1 = outcode(fx1 >> 8, fy1 >> 8, xmin, ymin, xmax, ymax);
98 void draw_line(int x0, int y0, int x1, int y1, unsigned short color)
100 int i, dx, dy, x_inc, y_inc, error;
101 unsigned short *fb = fb_pixels;
103 fb += y0 * fb_width + x0;
123 for(i=0; i<=dx; i++) {
134 for(i=0; i<=dy; i++) {