home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
The C Users' Group Library 1994 August
/
wc-cdrom-cusersgrouplibrary-1994-08.iso
/
listings
/
v_09_12
/
9n12040a
< prev
next >
Wrap
Text File
|
1991-10-14
|
3KB
|
71 lines
#include "solid.h"
void display_facet(struct solid_obj *obj_ptr, struct
facet *facet_ptr, int display_opt, int is_visible)
/* Projects facet onto 2-dimensional screen. */
{
struct vertex *vertex_ptr;
int x_first, y_first; /* screen coordinates for
first vertex of facet */
int vertex_ref_index;
float screen_x, screen_y; /* screen coords */
float x_normal, y_normal, z_normal; /* surface
normal vector */
if ((disp_hidden == LINE_NOSHOW || render_opt) &&
!is_visible) return; /* nothing to do */
if (display_opt && render_opt) {
render_facet(obj_ptr, facet_ptr);
return;
}
if (!display_opt) { /* don't display; just compute
screen coordinates */
for (vertex_ref_index = 0; vertex_ref_index <
facet_ptr->vertex_count;
++vertex_ref_index) { /* loop for each
vertex of this facet */
vertex_ptr = obj_ptr->vertex_first +
facet_ptr->vertex_index
[vertex_ref_index];
screen_x = proj_d * vertex_ptr->coord[0] /
proj_z;
screen_y = proj_d * vertex_ptr->coord[1] /
proj_z;
if (!init_screen) { /* first vertex;
initialize minimum and maximum */
screen_x_min = screen_x_max = screen_x;
screen_y_min = screen_y_max = screen_y;
init_screen = TRUE;
}
else { /* subsequent vertex; compare to
minimum and maximum */
if (screen_x < screen_x_min)
screen_x_min = screen_x;
if (screen_x > screen_x_max)
screen_x_max = screen_x;
if (screen_y < screen_y_min)
screen_y_min = screen_y;
if (screen_y > screen_y_max)
screen_y_max = screen_y;
}
continue;
}
}
else { /* display option is on */
if (!is_visible && (disp_hidden ==
LINE_BROKEN))
setlinestyle(DASHED_LINE, 0, NORM_WIDTH);
if (!is_visible && (color_visible !=
color_hidden))
setcolor(color_hidden);
draw_polygon(obj_ptr, facet_ptr);
if (!is_visible && (disp_hidden ==
LINE_BROKEN))
setlinestyle(SOLID_LINE, 0, NORM_WIDTH);
if (!is_visible && (color_visible !=
color_hidden))
setcolor(color_visible);
}
return;
}