hexwave_generate_linesegs()

static void fl::third_party::hexwave::hexwave_generate_linesegs ( hexvert vert[9], HexWave * hex, float dt )

static

Definition at line 123 of file stb_hexwave.cpp.hpp.

{
   int32_t j;
   float min_len = dt / 256.0f;
 
   vert[0].t = 0;
   vert[0].v = 0;
   vert[1].t = hex->current.zero_wait*0.5f;
   vert[1].v = 0;
   vert[2].t = 0.5f*hex->current.peak_time + vert[1].t*(1-hex->current.peak_time);
   vert[2].v = 1;
   vert[3].t = 0.5f;
   vert[3].v = hex->current.half_height;
 
   if (hex->current.reflect) {
      for (j=4; j <= 7; ++j) {
         vert[j].t = 1 -  vert[7-j].t;
         vert[j].v =    - vert[7-j].v;
      }
   } else {
      for (j=4; j <= 7; ++j) {
         vert[j].t =  0.5f +  vert[j-4].t;
         vert[j].v =        - vert[j-4].v;
      }
   }
   vert[8].t = 1;
   vert[8].v = 0;
 
   for (j=0; j < 8; ++j) {
      if (vert[j+1].t <= vert[j].t + min_len) {
          // if change takes place over less than a fraction of a sample treat as discontinuity
          //
          // otherwise the slope computation can blow up to arbitrarily large and we
          // try to generate a huge BLAMP and the result is wrong.
          //
          // why does this happen if the math is right? i believe if done perfectly,
          // the two BLAMPs on either side of the slope would cancel out, but our
          // BLAMPs have only limited sub-sample precision and limited integration
          // accuracy. or maybe it's just the math blowing up w/ floating point precision
          // limits as we try to make x * (1/x) cancel out
          //
          // min_len verified artifact-free even near nyquist with only oversample=4
         vert[j+1].t = vert[j].t;
      }
   }
 
   if (vert[8].t != 1.0f) {
      // if the above fixup moved the endpoint away from 1.0, move it back,
      // along with any other vertices that got moved to the same time
      float t = vert[8].t;
      for (j=5; j <= 8; ++j)
         if (vert[j].t == t)
            vert[j].t = 1.0f;
   }
 
   // compute the exact slopes from the final fixed-up positions
   for (j=0; j < 8; ++j)
      if (vert[j+1].t == vert[j].t)
         vert[j].s = 0;
      else
         vert[j].s = (vert[j+1].v - vert[j].v) / (vert[j+1].t - vert[j].t);
 
   // wraparound at end
   vert[8].t = 1;
   vert[8].v = vert[0].v;
   vert[8].s = vert[0].s;
}

References FL_NOEXCEPT, fl::hex, and fl::t.

Referenced by hexwave_generate_samples().

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