     // ta = camera direction (where the camera is looking)
     // cr = camera rotation
     //vec3 ro = vec3( -.5+3.5*cos(.1*a), 1.0, .5 + 4.0*sin(.1*a) );
-    vec3 ro = vec3( -.5+.2*cos(.1*a), 1., .0 + 2.*sin(.1*a) );
+    vec3 ro = vec3( -.5+2.*sin(1.*a), 1.+.5*cos(a), 2. );
     vec3 ta = vec3( .0 );
     // camera-to-world transformation
     mat3 ca = setCamera( ro, ta, .0 );

}
*/


float sdBloodVein(vec3 p) {
  vec3 c = vec3(2.,3.,5.);
  return -(length(p.xy-c.xz)-c.y);
}

float sdBloodVein2(vec3 p) {
  // the first constant sets size of torus
  // second sets size of middle
  return -(length(vec2(length(p.xz)-4.,p.y)) - 1.5);

  // float plasma1 = calcPlasma(pos.x, pos.y, pos.z, a / 10.0);
  return vec2(
    // tunnel shape
    sdBloodVein(pos + vec3(3.,-1.,1.)),

    // blobby surface
    // + 0.05 * sin(10.0 * pos.x) * sin(10.0 * pos.y) * sin(10.0 * pos.z),
