Fix T62730 Overlay: Selected edit hair points highlight is incorrect

This was due to the fact the drawing code was expecting the editpoints
to be equaly spaced. Reuse the code in particle.c to output the select
mask in red color channel of the particle (which is unused in new code).

1 files changed, 6 insertions, 4 deletions

diff --git a/source/blender/blenkernel/intern/particle.c b/source/blender/blenkernel/intern/particle.c
index 244ffb674a4..6b87cf2df81 100644
--- a/source/blender/blenkernel/intern/particle.c
+++ b/source/blender/blenkernel/intern/particle.c
@@ -3246,22 +3246,24 @@ static void psys_cache_edit_paths_iter(void *__restrict iter_data_v,
       }
     }
     else {
+      /* HACK(fclem): Instead of setting the color we pass the select state in the red channel.
+       * This is then picked up in DRW and the gpu shader will do the color interpolation. */
       if ((ekey + (pind.ekey[0] - point->keys))->flag & PEK_SELECT) {
         if ((ekey + (pind.ekey[1] - point->keys))->flag & PEK_SELECT) {
-          copy_v3_v3(ca->col, iter_data->sel_col);
+          ca->col[0] = 1.0f;
         }
         else {
           keytime = (t - (*pind.ekey[0]->time)) / ((*pind.ekey[1]->time) - (*pind.ekey[0]->time));
-          interp_v3_v3v3(ca->col, iter_data->sel_col, iter_data->nosel_col, keytime);
+          ca->col[0] = 1.0f - keytime;
         }
       }
       else {
         if ((ekey + (pind.ekey[1] - point->keys))->flag & PEK_SELECT) {
           keytime = (t - (*pind.ekey[0]->time)) / ((*pind.ekey[1]->time) - (*pind.ekey[0]->time));
-          interp_v3_v3v3(ca->col, iter_data->nosel_col, iter_data->sel_col, keytime);
+          ca->col[0] = keytime;
         }
         else {
-          copy_v3_v3(ca->col, iter_data->nosel_col);
+          ca->col[0] = 0.0f;
         }
       }
     }