1 files changed, 102 insertions, 0 deletions
diff --git a/src/gallium/auxiliary/util/u_split_prim.h b/src/gallium/auxiliary/util/u_split_prim.h
new file mode 100644
index 00000000000..3c438da0baf
--- /dev/null
+++ b/src/gallium/auxiliary/util/u_split_prim.h
@@ -0,0 +1,102 @@
+/* Originally written by Ben Skeggs for the nv50 driver*/
+#include <pipe/p_defines.h>
+
+struct u_split_prim {
+   void *priv;
+   void (*emit)(void *priv, unsigned start, unsigned count);
+   void (*edge)(void *priv, boolean enabled);
+
+   unsigned mode;
+   unsigned start;
+   unsigned p_start;
+   unsigned p_end;
+
+   uint repeat_first:1;
+   uint close_first:1;
+   uint edgeflag_off:1;
+};
+
+static INLINE void
+u_split_prim_init(struct u_split_prim *s,
+                  unsigned mode, unsigned start, unsigned count)
+{
+   if (mode == PIPE_PRIM_LINE_LOOP) {
+      s->mode = PIPE_PRIM_LINE_STRIP;
+      s->close_first = 1;
+   } else {
+      s->mode = mode;
+      s->close_first = 0;
+   }
+   s->start = start;
+   s->p_start = start;
+   s->p_end = start + count;
+   s->edgeflag_off = 0;
+   s->repeat_first = 0;
+}
+
+static INLINE boolean
+u_split_prim_next(struct u_split_prim *s, unsigned max_verts)
+{
+   int repeat = 0;
+
+   if (s->repeat_first) {
+      s->emit(s->priv, s->start, 1);
+      max_verts--;
+      if (s->edgeflag_off) {
+         s->edge(s->priv, TRUE);
+         s->edgeflag_off = FALSE;
+      }
+   }
+
+   if (s->p_start + s->close_first + max_verts >= s->p_end) {
+      s->emit(s->priv, s->p_start, s->p_end - s->p_start);
+      if (s->close_first)
+         s->emit(s->priv, s->start, 1);
+      return TRUE;
+   }
+
+   switch (s->mode) {
+   case PIPE_PRIM_LINES:
+      max_verts &= ~1;
+      break;
+   case PIPE_PRIM_LINE_STRIP:
+      repeat = 1;
+      break;
+   case PIPE_PRIM_POLYGON:
+      max_verts--;
+      s->emit(s->priv, s->p_start, max_verts);
+      s->edge(s->priv, FALSE);
+      s->emit(s->priv, s->p_start + max_verts, 1);
+      s->p_start += max_verts;
+      s->repeat_first = TRUE;
+      s->edgeflag_off = TRUE;
+      return FALSE;
+   case PIPE_PRIM_TRIANGLES:
+      max_verts = max_verts - (max_verts % 3);
+      break;
+   case PIPE_PRIM_TRIANGLE_STRIP:
+      /* to ensure winding stays correct, always split
+       * on an even number of generated triangles
+       */
+      max_verts = max_verts & ~1;
+      repeat = 2;
+      break;
+   case PIPE_PRIM_TRIANGLE_FAN:
+      s->repeat_first = TRUE;
+      repeat = 1;
+      break;
+   case PIPE_PRIM_QUADS:
+      max_verts &= ~3;
+      break;
+   case PIPE_PRIM_QUAD_STRIP:
+      max_verts &= ~1;
+      repeat = 2;
+      break;
+   default:
+      break;
+   }
+
+   s->emit (s->priv, s->p_start, max_verts);
+   s->p_start += (max_verts - repeat);
+   return FALSE;
+}