X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ian/git?p=moebius2.git;a=blobdiff_plain;f=project.c;h=266237f90b222be270b723c5845007ff85330e36;hp=1fb857630684fdaf4faf62b73dc42d3d1a7614fc;hb=456ce271eea85ff5acfe6a4416fa6c085d998c64;hpb=d7854bc606c02084a6287323cb6c994da977d121

diff --git a/project.c b/project.c
index 1fb8576..266237f 100644
--- a/project.c
+++ b/project.c
@@ -76,10 +76,14 @@ static void generate_display_list(void) {
 }    
 
 static int dl_compare(const void *tav, const void *tbv) {
+  int i;
   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];
+  double za=0, zb=0;
+  for (i=0; i<3; i++) {
+    za += ta->vertex[i][2];
+    zb += tb->vertex[i][2];
+  }
   return za > zb ? -1 :
          za < zb ? +1 : 0;
 }
@@ -92,15 +96,20 @@ static void sort_display_list(void) {
 
 #define WSZ 400
 
+typedef struct { GC fillgc, linegc; } DrawingMode;
+
 static Display *display;
 static Pixmap pixmap, doublebuffers[2];
 static Window window;
-static GC linegc, fillgc;
+
+static DrawingMode dmred, dmblue, dmwhite;
+static const DrawingMode *dmcurrent;
 static int wwidth=WSZ, wheight=WSZ, wmindim=WSZ, wmaxdim=WSZ;
 static int ncut, currentbuffer, x11depth, x11screen;
+XVisualInfo visinfo;
 
-static double scale= 0.3;
-static double eye_z= -10, eye_x= 0;
+static double sizeadj_scale= 0.3, eyes_apart, scale_wmindim;
+static double eye_z= -10, eye_x=0;
 static double cut_z= -9;
 
 static void drawtriangle(const Triangle *t) {
@@ -116,13 +125,15 @@ static void drawtriangle(const Triangle *t) {
     if (z < cut_z) { ncut++; return; }
     
     double zezezp= eye_z / (eye_z - z);
-    points[i].x= scale * wmindim * (zezezp * (x - eye_x) + eye_x) + wwidth/2;
-    points[i].y= scale * wmindim * (zezezp *  y                 ) + wheight/2;
+    points[i].x= scale_wmindim * (zezezp * (x - eye_x) + eye_x) + wwidth/2;
+    points[i].y= scale_wmindim * (zezezp *  y                 ) + wheight/2;
   }
   points[3]= points[0];
 
-  XA( XFillPolygon(display,pixmap,fillgc, points,3,Convex,CoordModeOrigin) );
-  XA( XDrawLines(display,pixmap,linegc,points, 4,CoordModeOrigin) );
+  XA( XFillPolygon(display,pixmap, dmcurrent->fillgc,
+		   points,3,Convex,CoordModeOrigin) );
+  XA( XDrawLines(display,pixmap, dmcurrent->linegc,
+		 points, 4,CoordModeOrigin) );
 }
 
 static const unsigned long core_event_mask=
@@ -136,21 +147,35 @@ static void mkpixmaps(void) {
   currentbuffer= 0;
 }
 
-static void display_prepare(void) {
+static void mkgcs(DrawingMode *dm, unsigned long planes) {
   XGCValues gcv;
+
+  gcv.function= GXcopy;
+  gcv.foreground= WhitePixel(display,x11screen);
+  gcv.plane_mask= planes;
+  dm->linegc= XCreateGC(display,pixmap,
+			GCFunction|GCForeground|GCPlaneMask,
+			&gcv);
+
+  gcv.function= GXclear;
+  dm->fillgc= XCreateGC(display,pixmap,
+			GCFunction|GCPlaneMask,
+			&gcv);
+}
+
+static void display_prepare(void) {
   XSetWindowAttributes wa;
-  XVisualInfo vinfo;
   XSizeHints hints;
   
   XA( display= XOpenDisplay(0) );
   x11screen= DefaultScreen(display);
   x11depth= DefaultDepth(display,x11screen);
-  XA( XMatchVisualInfo(display,x11screen,x11depth, TrueColor,&vinfo) );
+  XA( XMatchVisualInfo(display,x11screen,x11depth, TrueColor,&visinfo) );
   
   wa.event_mask= core_event_mask;
   XA( window= XCreateWindow(display, DefaultRootWindow(display),
 			    0,0, wwidth,wheight, 0,x11depth,
-			    InputOutput, vinfo.visual,
+			    InputOutput, visinfo.visual,
 			    CWEventMask, &wa) );
 
   hints.flags= USPosition;
@@ -160,25 +185,39 @@ static void display_prepare(void) {
 
   mkpixmaps();
 
-  gcv.function= GXcopy;
-  gcv.plane_mask= ~0UL;
-  gcv.foreground= WhitePixel(display,x11screen);
-  linegc= XCreateGC(display,pixmap, GCFunction|GCPlaneMask|GCForeground, &gcv);
-  
-  gcv.function= GXclear;
-  gcv.plane_mask= ~0UL;
-  fillgc= XCreateGC(display,pixmap, GCFunction|GCPlaneMask, &gcv);
+  mkgcs(&dmwhite, AllPlanes);
+  mkgcs(&dmblue, visinfo.blue_mask);
+  mkgcs(&dmred, visinfo.red_mask);
 }
 
-static void display_conformation(void) {
+static void drawtriangles(const DrawingMode *dm) {
   Triangle *const *t;
   int i;
-  
-  pixmap= doublebuffers[currentbuffer];
-  XA( XFillRectangle(display,pixmap,fillgc,0,0,wwidth,wheight) );
+
+  dmcurrent= dm;
   for (i=0, t=displaylist, ncut=0; i<ntris; i++, t++)
     drawtriangle(*t);
-  printf("shown, %d/%d triangles cut\n", ncut, ntris);
+}
+
+static void display_conformation(void) {
+  pixmap= doublebuffers[currentbuffer];
+
+  XA( XFillRectangle(display,pixmap,dmwhite.fillgc,0,0,wwidth,wheight) );
+
+  if (eyes_apart > 0) {
+    const double preferred=0.05, beyond=0.07;
+
+    eye_x= eyes_apart < preferred ? eyes_apart :
+           eyes_apart < beyond ? preferred :
+           eyes_apart - (beyond - preferred);
+    eye_x /= sizeadj_scale;
+    drawtriangles(&dmblue);
+    eye_x= -eye_x;
+    drawtriangles(&dmred);
+  } else {
+    drawtriangles(&dmwhite);
+    printf("shown, %d/%d triangles cut\n", ncut, ntris);
+  }
   
   XA( XSetWindowBackgroundPixmap(display,window,pixmap) );
   XA( XClearWindow(display,window) );
@@ -186,6 +225,7 @@ static void display_conformation(void) {
 }
 
 static void show(void) {
+  scale_wmindim= sizeadj_scale * wmindim;
   read_input();
   transform_coordinates();
   generate_display_list();
@@ -225,65 +265,146 @@ static void drag_none_conclude(void) { }
 static void drag_none_abandon(void) { }
 DRAG(none);
 
+static void pvectorcore(const char *n, double v[D3]) {
+  int k;
+  printf("%10s [ ",n);
+  K printf("%# 10.10f ",v[k]);
+  printf("]\n");
+}
+static void pvector(const char *n, double v[D3]) {
+  pvectorcore(n,v);
+  putchar('\n');
+}
 static void pmatrix(const char *n, double m[D3][D3]) {
-  int j,k;
-  for (j=0; j<D3; j++) {
-    printf("%10s [ ",n);
-    K printf("%# f ",m[j][k]);
-    printf("]\n");
-    n="";
-  }
+  int j;
+  for (j=0; j<D3; j++) { pvectorcore(n,m[j]); n=""; }
+  putchar('\n');
 }
-
 #define PMATRIX(x) pmatrix(#x,x);
 
 static void drag_rotate_delta(double dx, double dy) {
-  /* We multiple our transformation matrix by this matrix:
-   *     [  1   0   0 ]
-   *     [  0   1   0 ]
-   *     [ dx  dy   1 ]
-   * and then renormalise.
+  /* We multiple our transformation matrix by a matrix:
+   *
+   * If we just had y movement, we would rotate about x axis:
+   *  rotation X = [  1    0   0 ]
+   *               [  0   cy  sy ]
+   *               [  0  -sy  cy ]
+   *  where cy and sy are sin and cos of y rotation
+   *
+   * But we should pre-rotate this by a rotation about the z axis
+   * to get it to the right angle (to include x rotation).  So
+   * we make cy and sy be cos() and sin(hypot(x,y)) and use
+   * with cr,sr as cos() and sin(atan2(y,y)):
+   *
+   * Ie we would do  T' = R^T X R T   where
+   *             or  T' =    C    T   where  C = R^T X R  and
+   *
+   *  adjustment R = [  cr  sr  0 ]
+   *                 [ -sr  cr  0 ]
+   *                 [  0    0  1 ]
    */
 
-  static double rotateby[D3][D3]= {{1,0,0},{0,1,0},{-20,-20,1}};
-  static GSL_MATRIX(rotateby);
+  double rotx[D3][D3], adjr[D3][D3];
+  GSL_MATRIX(rotx);
+  GSL_MATRIX(adjr);
 
-  double qr[D3][D3];
-  gsl_matrix qr_gsl= { D3,D3,D3,&qr[0][0] };
+  static double temp[D3][D3], change[D3][D3];
+  static GSL_MATRIX(temp);
+  static GSL_MATRIX(change);
 
-  double tau[D3];
-  GSL_VECTOR(tau);
+  double d= hypot(dx,dy);
+  if (d < 1e-6) return;
+
+  double ang= d*2.0;
+  
+  double cy= cos(ang);
+  double sy= sin(ang);
+  double cr= -dy / d;
+  double sr=  dx / d;
+  printf("\n d=%g cy,sy=%g,%g cr,sr=%g,%g\n\n", d,cy,sy,cr,sr);
   
-  rotateby[2][0]= dx;
-  rotateby[2][1]= dy;
+  rotx[0][0]=   1;    rotx[0][1]=   0;     rotx[0][2]=  0;
+  rotx[1][0]=   0;    rotx[1][1]=  cy;     rotx[1][2]= sy;
+  rotx[2][0]=   0;    rotx[2][1]= -sy;     rotx[2][2]= cy;
+  PMATRIX(rotx);
 
-  PMATRIX(rotateby);
+  adjr[0][0]=  cr;    adjr[0][1]=  sr;     adjr[0][2]=  0;
+  adjr[1][0]= -sr;    adjr[1][1]=  cr;     adjr[1][2]=  0;
+  adjr[2][0]=   0;    adjr[2][1]=   0;     adjr[2][2]=  1;
+  PMATRIX(adjr);
+
+  GA( gsl_blas_dgemm(CblasNoTrans,CblasNoTrans, 1.0,
+		     &rotx_gsl,&adjr_gsl,
+		     0.0, &temp_gsl) );
+  PMATRIX(temp);
+  
+  GA( gsl_blas_dgemm(CblasTrans,CblasNoTrans, 1.0,
+		     &adjr_gsl,&temp_gsl,
+		     0.0, &change_gsl) );
+  PMATRIX(change);
+
+  static double skew[D3][D3];
+  static GSL_MATRIX(skew);
   
   GA( gsl_blas_dgemm(CblasNoTrans,CblasNoTrans, 1.0,
-		     &rotateby_gsl,&transform_gsl, 0.0,&qr_gsl) );
+		     &change_gsl,&transform_gsl,
+		     0.0, &skew_gsl) );
+  PMATRIX(skew);
 
-  pmatrix("input", qr);
+  memcpy(&transform,&skew,sizeof(transform));
+  show();
+  return;
 
-  GA( gsl_linalg_QR_decomp(&qr_gsl, &tau_gsl) );
+  /* Now we want to normalise skew, the result becomes new transform */
+  double svd_v[D3][D3];
+  GSL_MATRIX(svd_v);
 
-  pmatrix("mangled", qr);
+  double sigma[D3], tau[D3];
+  GSL_VECTOR(sigma);
+  GSL_VECTOR(tau);
+  
+  /* We use notation from Wikipedia Polar_decomposition
+   *     Wikipedia's  W      is GSL's U
+   *     Wikipedia's  Sigma  is GSL's S
+   *     Wikipedia's  V      is GSL's V
+   *     Wikipedia's  U      is our desired result
+   * Wikipedia which says if the SVD is    A = W Sigma V*
+   * then the polar decomposition is       A = U P
+   *   where                               P = V Sigma V*
+   *   and                                 U = W V*
+   */
+  
+  GA( gsl_linalg_SV_decomp(&skew_gsl, &svd_v_gsl, &sigma_gsl, &tau_gsl) );
+  pmatrix("W",    skew);
+  pvector("Sigma",sigma);
+  pmatrix("V",    svd_v);
 
-  GA( gsl_linalg_QR_unpack(&qr_gsl, &tau_gsl,
-			   &transform_gsl, &rotateby_gsl /*dummy*/) );
+  /* We only need U, not P. */
+  GA( gsl_blas_dgemm(CblasNoTrans,CblasTrans, 1.0,
+		     &skew_gsl,&svd_v_gsl,
+		     0.0,&transform_gsl) );
 
-  pmatrix("Q", transform);
-  pmatrix("R", rotateby);
+  pmatrix("U", transform);
 
   printf("drag_rotate_delta...\n");
   show();
 }
 DRAG_SAVING(rotate, transform);
 
-static void drag_scale_delta(double dx, double dy) {
-  scale *= pow(3.0, dy);
+static void drag_sizeadj_delta(double dx, double dy) {
+  sizeadj_scale *= pow(3.0, -dy);
+  show();
+}
+DRAG_SAVING(sizeadj, sizeadj_scale);
+
+static void drag_3d_delta(double dx, double dy) {
+  const double min_eyes_apart= -0.02;
+  eyes_apart += dx * 0.1;
+  if (eyes_apart < min_eyes_apart) eyes_apart= min_eyes_apart;
+  printf("sizeadj eyes_apart %g\n", eyes_apart);
   show();
 }
-DRAG_SAVING(scale, scale);
+DRAG_SAVING(3d, eyes_apart);
 
 static const Drag *drag= &drag_none;
 
@@ -308,7 +429,8 @@ static void event_button(XButtonEvent *e) {
     }
     switch (e->button) {
     case Button1: drag= &drag_rotate;  break;
-    case Button2: drag= &drag_scale;   break;
+    case Button2: drag= &drag_sizeadj; break;
+    case Button3: drag= &drag_3d;      break;
     default: printf("unknown drag start %d\n", e->button);
     }
     printf("drag=%s press button=%lu start %d,%d\n",
@@ -381,11 +503,9 @@ int main(int argc, const char *const *argv) {
     case ConfigureNotify:   event_config(&event.xconfigure);  break;
 
     case MotionNotify:
-#if 0
       motion_x= event.xmotion.x;
       motion_y= event.xmotion.y;
       motion_deferred= 1;
-#endif
       continue;
       
     default: