allow drawing walls in random order

2 files changed, 3 insertions, 3 deletions

diff --git a/shaders/tile.cpp b/shaders/tile.cpp
index c8261acd..22a91497 100644
--- a/shaders/tile.cpp
+++ b/shaders/tile.cpp
@@ -66,11 +66,11 @@ void tile_shader::_draw()
     }
 }
 
-float tile_shader::depth_value(const local_coords& xy) noexcept
+float tile_shader::depth_value(const local_coords& xy, float offset) noexcept
 {
     constexpr float max = (TILE_MAX_DIM+1)*(TILE_MAX_DIM+1) * .5f;
     constexpr float min = -1 + 1.f/256;
-    float value = min + xy.to_index()/max;
+    float value = min + (xy.to_index() + offset)/max;
     fm_assert(value > -1 && value < 1);
     return value;
 }
diff --git a/shaders/tile.hpp b/shaders/tile.hpp
index 8a45e1e7..4acc556b 100644
--- a/shaders/tile.hpp
+++ b/shaders/tile.hpp
@@ -27,7 +27,7 @@ struct tile_shader : GL::AbstractShaderProgram
     tile_shader& set_camera_offset(Vector2d camera_offset);
     Vector4 tint() const { return _tint; }
     tile_shader& set_tint(const Vector4& tint);
-    static float depth_value(const local_coords& xy) noexcept;
+    static float depth_value(const local_coords& xy, float offset = 0) noexcept;
 
     template<typename T = float> static constexpr Math::Vector2<T> project(const Math::Vector3<T>& pt);
     template<typename T = float> static constexpr Math::Vector2<T> unproject(const Math::Vector2<T>& px);