d3d12: Only enable depth bias for triangle primitives

src/gallium/drivers/d3d12/d3d12_pipeline_state.cpp

@@ -126,18 +126,26 @@ fill_so_declaration(const struct pipe_stream_output_info *info,
 static bool
 depth_bias(struct d3d12_rasterizer_state *state, enum pipe_prim_type reduced_prim)
 {
-   switch (reduced_prim) {
-   case PIPE_PRIM_POINTS:
-      return state->base.offset_point;
+   /* glPolygonOffset is supposed to be only enabled when rendering polygons.
+    * In d3d12 case, all polygons (and quads) are lowered to triangles */
+   if (reduced_prim != PIPE_PRIM_TRIANGLES)
+      return false;
 
-   case PIPE_PRIM_LINES:
-      return state->base.offset_line;
+   unsigned fill_mode = state->base.cull_face == PIPE_FACE_FRONT ? state->base.fill_back
+                                                                 : state->base.fill_front;
 
-   case PIPE_PRIM_TRIANGLES:
+   switch (fill_mode) {
+   case PIPE_POLYGON_MODE_FILL:
       return state->base.offset_tri;
 
+   case PIPE_POLYGON_MODE_LINE:
+      return state->base.offset_line;
+
+   case PIPE_POLYGON_MODE_POINT:
+      return state->base.offset_point;
+
    default:
-      unreachable("unexpected reduced prim");
+      unreachable("unexpected fill mode");
    }
 }