tetris: ensure continued color changes #825

src/tetris/stain.h

@@ -1,12 +1,13 @@
 void StainBoard(int dimy, int dimx){
   board_->cursor_move(0, 1);
   const int l = level_ - 1;
-  int high = 0xff - l * 0x10, low = l * 0x20; // rgb calculation limits us to 16 levels (1--16)
+  int high = 0xff - (l / 2) * 0x10;
+  int low = l * 0x10;
   int green = 0;
   if(low >= 0x100){
     low = low % 0x100;
-    green = (l - 8) * 0x20;
   }
+  green = (l / 2) * 0x20;
   uint64_t tl = 0, tr = 0, bl = 0, br = 0;
   const int c1 = level_ % 2 ? high : low; const int c2 = level_ % 2 ? low : high;
   channels_set_fg_rgb(&tl, c1, green, c2); channels_set_bg_alpha(&tl, CELL_ALPHA_TRANSPARENT);