--- /dev/null
+/*
+ * Displays a conformation
+ */
+
+#include <X11/Xlib.h>
+#include <X11/Xutil.h>
+
+#include "mgraph.h"
+
+#define MAXTRIS (N*2)
+
+typedef struct { double vertex[3][D3]; } Triangle;
+
+static Triangle trisbuffer[MAXTRIS], *displaylist[MAXTRIS];
+static int ntris;
+static Vertices conformation;
+
+const char *input_filename;
+
+static void read_input(void) {
+ FILE *f;
+ int r;
+
+ f= fopen(input_filename, "rb"); if (!f) diee("input file");
+ errno= 0;
+ r= fread(&conformation,1,sizeof(conformation),f); if (r!=1) diee("fread");
+ fclose(f);
+}
+
+static void transform_coordinates(void) {
+ int v;
+
+ FOR_VERTEX(v) {
+ }
+}
+
+static void addtriangle(int va, int vb, int vc) {
+ Triangle *t= &trisbuffer[ntris];
+ int k;
+
+ assert(ntris < MAXTRIS);
+ K {
+ t->vertex[0][k]= conformation[va][k];
+ t->vertex[1][k]= conformation[vb][k];
+ t->vertex[2][k]= conformation[vc][k];
+ }
+ displaylist[ntris++]= t;
+}
+
+static void generate_display_list(void) {
+ int vb, ve[3], e;
+
+ FOR_VERTEX(vb) {
+ /* We use the two triangles in the parallelogram vb, vb+e1, vb+e0, vb+e2.
+ * We go round each triangle clockwise (although our surface is non-
+ * orientable so it shouldn't matter).
+ */
+ for (e=0; e<3; e++) ve[e]= EDGE_END2(vb,e);
+ if (ve[0]>=0) {
+ if (ve[1]>=0) addtriangle(vb,ve[0],ve[1]);
+ if (ve[2]>=0) addtriangle(vb,ve[2],ve[0]);
+ }
+ }
+}
+
+static int dl_compare(const void *tav, const void *tbv) {
+ const Triangle *const *tap= tav, *ta= *tap;
+ const Triangle *const *tbp= tbp, *tb= *tbp;
+ double za= ta->vertex[0][2];
+ double zb= tb->vertex[0][2];
+ return za > zb ? +1 :
+ za < zb ? -1 : 0;
+}
+
+static void sort_display_list(void) {
+ qsort(displaylist, ntris, sizeof(*displaylist), dl_compare);
+}
+
+/*---------- X stuff ----------*/
+
+#define WSZ 400
+
+static Display *display;
+static Pixmap pixmap, doublebuffers[2];
+static Window window;
+static GC linegc, fillgc;
+static int wwidth=WSZ, wheight=WSZ, currentbuffer;
+
+static double scale= WSZ * 0.3;
+static double eye_z= -10, eye_x= 0;
+static double cut_z= -9;
+
+static void xdie(int l, const char *str) {
+ fprintf(stderr,"X library call failed, line %d: %s\n", l, str);
+}
+
+#define XA(w) ((w) ? (void)0 : xdie(__LINE__, #w))
+
+static void drawtriangle(const Triangle *t) {
+ XPoint points[4];
+ int i;
+
+ for (i=0; i<3; i++) {
+ double *v= t->vertex[i];
+ double x= v[0];
+ double y= v[1];
+ double z= v[2];
+ if (z < cut_z) return;
+ double zezezp= eye_z / (eye_z - z);
+ points[i].x= scale * (zezezp * (x - eye_x) + eye_x);
+ points[i].y= scale * (zezezp * y );
+ }
+ points[3]= points[0];
+
+ XA(! XFillPolygon(display,pixmap,fillgc, points,3,Convex,CoordModeOrigin) );
+ XA(! XDrawLines(display,pixmap,linegc,points, 4,CoordModeOrigin) );
+}
+
+static void display_prepare(void) {
+ XGCValues gcv;
+ XSetWindowAttributes wa;
+ int screen, depth;
+ XVisualInfo vinfo;
+
+ XA( display= XOpenDisplay(0) );
+ screen= DefaultScreen(display);
+ depth= DefaultDepth(display,screen);
+ XA(! XMatchVisualInfo(display,screen,depth, TrueColor,&vinfo) );
+
+ wa.event_mask= ButtonPress|ConfigureNotify;
+ XA( window= XCreateWindow(display, DefaultRootWindow(display),
+ 10,10, wwidth,wheight, 0,depth,
+ InputOutput, vinfo.visual,
+ CWEventMask, &wa) );
+
+ for (currentbuffer=0; currentbuffer<2; currentbuffer++) {
+ XA( pixmap= XCreatePixmap(display,window,wwidth,wheight,depth) );
+ doublebuffers[currentbuffer]= pixmap;
+ }
+
+ gcv.function= GXcopy;
+ gcv.plane_mask= ~0UL;
+ gcv.foreground= WhitePixel(display,screen);
+ linegc= XCreateGC(display,pixmap, GCFunction|GCPlaneMask|GCForeground, &gcv);
+
+ gcv.function= GXclear;
+ gcv.plane_mask= ~0UL;
+ fillgc= XCreateGC(display,pixmap, GCFunction|GCPlaneMask, &gcv);
+
+ currentbuffer= 0;
+}
+
+static void display_conformation(void) {
+ Triangle *const *t;
+ int i;
+
+ pixmap= doublebuffers[currentbuffer];
+ XA(! XFillRectangle(display,pixmap,fillgc,0,0,wwidth,wheight) );
+ for (i=0, t=displaylist; i<ntris; i++, t++)
+ drawtriangle(*t);
+ XA(! XSetWindowBackgroundPixmap(display,window,pixmap) );
+ XA(! XClearWindow(display,window) );
+ currentbuffer= !currentbuffer;
+}
+
+static void show(void) {
+ read_input();
+ transform_coordinates();
+ generate_display_list();
+ sort_display_list();
+ display_conformation();
+}
+
+
+int main(int argc, const char *const *argv) {
+ if (argc != 2 || argv[1][0]=='-') {
+ fputs("need filename\n",stderr); exit(8);
+ }
+ input_filename= argv[1];
+
+ read_input();
+ display_prepare();
+ show();
+ XSync(display,0);
+ for (;;);
+}
+