fix z value discontinuity on chunk boundaries

3 files changed, 15 insertions, 12 deletions

diff --git a/shaders/tile.cpp b/shaders/tile.cpp
index ff08de2e..9df05f8e 100644
--- a/shaders/tile.cpp
+++ b/shaders/tile.cpp
@@ -31,7 +31,7 @@ tile_shader::tile_shader()
 
     set_scale({640, 480});
     set_tint({1, 1, 1, 1});
-    setUniform(OffsetUniform, Vector2{});
+    setUniform(OffsetUniform, Vector3{});
 }
 
 tile_shader::~tile_shader() = default;
@@ -43,9 +43,10 @@ tile_shader& tile_shader::set_scale(const Vector2& scale)
     return *this;
 }
 
-tile_shader& tile_shader::set_camera_offset(Vector2d camera_offset)
+tile_shader& tile_shader::set_camera_offset(const Vector2d& camera_offset, float depth_offset)
 {
     _camera_offset = camera_offset;
+    _depth_offset = depth_offset;
     return *this;
 }
 
@@ -58,11 +59,12 @@ tile_shader& tile_shader::set_tint(const Vector4& tint)
 void tile_shader::_draw()
 {
     fm_assert(std::fabs(_camera_offset[0]) < 1 << 24 && std::fabs(_camera_offset[1]) < 1 << 24);
+    fm_assert(std::fabs(_depth_offset) < 1 << 24);
 
     if (_tint != _real_tint)
         setUniform(TintUniform, _real_tint = _tint);
 
-    if (const auto offset = Vector2{(float)_camera_offset[0], (float)_camera_offset[1]};
+    if (const auto offset = Vector3((float)_camera_offset[0], (float)_camera_offset[1], _depth_offset);
         offset != _real_camera_offset)
     {
         _real_camera_offset = offset;
@@ -72,11 +74,7 @@ void tile_shader::_draw()
 
 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() + offset)/max;
-    fm_assert(value > -1 && value < 1);
-    return value;
+    return (xy.to_index() + offset)*depth_tile_size;
 }
 
 } // namespace floormat
diff --git a/shaders/tile.hpp b/shaders/tile.hpp
index 72f36c40..d6eb7cca 100644
--- a/shaders/tile.hpp
+++ b/shaders/tile.hpp
@@ -1,5 +1,6 @@
 #pragma once
 #include "compat/defs.hpp"
+#include "tile-defs.hpp"
 #include <Magnum/GL/AbstractShaderProgram.h>
 #include <Magnum/Math/Vector2.h>
 #include <Magnum/Math/Vector3.h>
@@ -24,9 +25,10 @@ struct tile_shader : GL::AbstractShaderProgram
     Vector2 scale() const { return _scale; }
     tile_shader& set_scale(const Vector2& scale);
     Vector2d camera_offset() const { return _camera_offset; }
-    tile_shader& set_camera_offset(Vector2d camera_offset);
+    tile_shader& set_camera_offset(const Vector2d& camera_offset, float depth_offset);
     Vector4 tint() const { return _tint; }
     tile_shader& set_tint(const Vector4& tint);
+    float depth_offset() const { return _depth_offset; }
     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);
@@ -35,13 +37,16 @@ struct tile_shader : GL::AbstractShaderProgram
     template<typename T, typename... Xs>
     decltype(auto) draw(T&& mesh, Xs&&... xs);
 
+    static constexpr float depth_tile_size = 1.f/(256 * TILE_COUNT);
+
 private:
     void _draw();
 
     Vector2d _camera_offset;
     Vector4 _tint, _real_tint;
     Vector2 _scale;
-    Vector2 _real_camera_offset;
+    Vector3 _real_camera_offset;
+    float _depth_offset = 0;
 
     enum { ScaleUniform = 0, OffsetUniform = 1, TintUniform = 2, };
 };
diff --git a/shaders/tile.vert b/shaders/tile.vert
index ad038e6d..a539ed6b 100644
--- a/shaders/tile.vert
+++ b/shaders/tile.vert
@@ -1,7 +1,7 @@
 precision highp float;
 
 layout (location = 0) uniform vec2 scale;
-layout (location = 1) uniform vec2 offset;
+layout (location = 1) uniform vec3 offset;
 
 layout (location = 0) in vec4 position;
 layout (location = 1) in vec2 texcoords;
@@ -10,6 +10,6 @@ noperspective out vec2 frag_texcoords;
 
 void main() {
     float x = -position.y, y = -position.x, z = position.z;
-    gl_Position = vec4((x-y+offset.x)*scale.x, ((x+y+z*2)*.59-offset.y)*scale.y, depth, 1);
+    gl_Position = vec4((x-y+offset.x)*scale.x, ((x+y+z*2)*.59-offset.y)*scale.y, offset.z + depth, 1);
     frag_texcoords = texcoords;
 }