There was an attempt

Gemfile

@@ -8,4 +8,6 @@ gemspec
 gem "gtk3"
 gem "opengl-bindings2"
 gem "rake"
-gem "optparse"
+gem "optparse"
+gem 'rubocop', group: 'development'
+gem 'ruby-vips'

Gemfile.lock

@@ -6,6 +6,7 @@ PATH
 GEM
   remote: https://rubygems.org/
   specs:
+    ast (2.4.2)
     atk (3.5.1)
       glib2 (= 3.5.1)
     cairo (1.17.5)
@@ -15,6 +16,7 @@ GEM
     cairo-gobject (3.5.1)
       cairo (>= 1.16.2)
       glib2 (= 3.5.1)
+    ffi (1.12.2)
     fiddle (1.1.0)
     gdk3 (3.5.1)
       cairo-gobject (= 3.5.1)
@@ -36,17 +38,40 @@ GEM
       gdk_pixbuf2 (= 3.5.1)
       gio2 (= 3.5.1)
       pango (= 3.5.1)
+    json (2.6.2)
     matrix (0.4.2)
     native-package-installer (1.1.4)
     opengl-bindings2 (2.0.0)
     optparse (0.2.0)
     pango (3.5.1)
       cairo-gobject (= 3.5.1)
       gobject-introspection (= 3.5.1)
+    parallel (1.22.1)
+    parser (3.1.2.1)
+      ast (~> 2.4.1)
     pkg-config (1.4.7)
+    rainbow (3.1.1)
     rake (13.0.6)
     red-colors (0.3.0)
       matrix
+    regexp_parser (2.5.0)
+    rexml (3.2.5)
+    rubocop (1.35.1)
+      json (~> 2.3)
+      parallel (~> 1.10)
+      parser (>= 3.1.2.1)
+      rainbow (>= 2.2.2, < 4.0)
+      regexp_parser (>= 1.8, < 3.0)
+      rexml (>= 3.2.5, < 4.0)
+      rubocop-ast (>= 1.20.1, < 2.0)
+      ruby-progressbar (~> 1.7)
+      unicode-display_width (>= 1.4.0, < 3.0)
+    rubocop-ast (1.21.0)
+      parser (>= 3.1.1.0)
+    ruby-progressbar (1.11.0)
+    ruby-vips (2.1.4)
+      ffi (~> 1.12)
+    unicode-display_width (2.2.0)
 
 PLATFORMS
   x64-mingw-ucrt
@@ -58,6 +83,8 @@ DEPENDENCIES
   opengl-bindings2
   optparse
   rake
+  rubocop
+  ruby-vips
 
 BUNDLED WITH
    2.3.14

lib/luminol.rb

@@ -10,8 +10,8 @@ def self.start
 
       app = Application.new
       puts app.run
-    rescue Exception => e
-      raise e
+    rescue StandardError => e
+      # raise e
       dialog = Gtk::MessageDialog.new(
         buttons: :ok_cancel,
         message_type: :error

lib/luminol/core/shader/GeometryRenderer.frag

@@ -0,0 +1,10 @@
+#version 330 core
+
+uniform sampler2D texture0;
+in vec2 texCoord;
+out vec4 FragColor;
+
+void main()
+{
+    FragColor = texture(texture0, texCoord);
+}

lib/luminol/core/shader/GeometryRenderer.geom

@@ -0,0 +1,39 @@
+#version 330 core
+
+uniform mat4 projection;
+
+in VS_OUT {
+    uint tileId;
+} gs_in[];
+
+out vec2 texCoord;
+
+layout (points) in;
+layout (triangle_strip, max_vertices = 4) out;
+
+void main() {
+    uint tileId = gs_in[0].tileId & 255u;
+    float tileX = float(tileId & 15u) / 16.0;
+    float tileY = float((tileId >> 4u) & 15u) / 16.0;
+
+    const float B = 1 / 256.0;
+    const float S = 1 / 16.0;
+
+    gl_Position = projection * gl_in[0].gl_Position;
+    texCoord = vec2(tileX + B, tileY + B);
+    EmitVertex();
+
+    gl_Position = projection * (gl_in[0].gl_Position + vec4(1.0, 0.0, 0.0, 0.0));
+    texCoord = vec2(tileX + S - B, tileY + B);
+    EmitVertex();
+
+    gl_Position = projection * (gl_in[0].gl_Position + vec4(0.0, 1.0, 0.0, 0.0));
+    texCoord = vec2(tileX + B, tileY + S - B);
+    EmitVertex();
+
+    gl_Position = projection * (gl_in[0].gl_Position + vec4(1.0, 1.0, 0.0, 0.0));
+    texCoord = vec2(tileX + S - B, tileY + S - B);
+    EmitVertex();
+
+    EndPrimitive();
+}

lib/luminol/core/shader/GeometryRenderer.vert

@@ -0,0 +1,20 @@
+#version 330 core
+
+uniform mat4 projection;
+uniform ivec2 mapSize;
+
+layout (location = 0) in uint aTileId;
+
+out VS_OUT {
+    uint tileId;
+} vs_out;
+
+void main()
+{
+    int i = gl_VertexID;
+    float x = float(i / mapSize.y); //float(i & 15);
+    float y = float(i % mapSize.y); //float((i >> 4) & 15);
+    gl_Position = vec4(x, y, 0, 1);
+
+    vs_out.tileId = aTileId;
+}

lib/luminol/core/texture.rb

@@ -0,0 +1,43 @@
+require 'opengl'
+
+class Texture
+
+  attr_reader :id, :height, :width
+
+  def initialize(*paths)
+    pixbuf = System::Cache.load_image(*paths)
+
+    @width, @height = pixbuf.width, pixbuf.height
+    pixels = pixbuf.pixels
+
+    id_buf = ' ' * 4
+    GL.GenTextures(1, id_buf)
+    @id = id_buf.unpack1('L')
+
+    bind
+    GL.TexImage2D(
+      GL::TEXTURE_2D,
+      0,
+      GL::RGB,
+      @width,
+      @height,
+      0,
+      GL::RGB,
+      GL::UNSIGNED_BYTE,
+      pixels.pack("C#{pixels.size}")
+    )
+    unbind
+  end
+
+  def bind
+    GL.BindTexture(GL::TEXTURE_2D, @id)
+  end
+
+  def unbind
+    GL.BindTexture(GL::TEXTURE_2D, 0)
+  end
+
+  def delete
+    GL.DeleteTextures(1, [@id].pack('L'))
+  end
+end

lib/luminol/core/tileatlas.rb

@@ -0,0 +1,16 @@
+require 'opengl'
+require_relative '../core/texture'
+
+class TileAtlas
+  def initialize
+    @tileset_tex = Texture.new 'Graphics', 'Tilesets', System.tileset.tileset_name
+  end
+
+  def bind
+    @tileset_tex.bind
+  end
+
+  def dispose
+    @tileset_tex.delete
+  end
+end