From 2ed4868973b1b266954858d84d8fdedb8351b345 Mon Sep 17 00:00:00 2001
From: Matthew Berry <me@mattrb.com>
Date: Sat, 31 Jul 2021 16:16:33 -0700
Subject: [PATCH] minor frontend cleanup

---
 src/crab.cr                                   |  3 ---
 src/crab/common/frontend.cr                   |  2 --
 .../controllers/stubbed_controller.cr         |  1 +
 .../frontend/sdl_opengl_imgui_frontend.cr     | 21 ++++++++++---------
 src/crab/common/shaders/stubbed_colors.frag   | 10 +++++++++
 5 files changed, 22 insertions(+), 15 deletions(-)
 create mode 100644 src/crab/common/shaders/stubbed_colors.frag

diff --git a/src/crab.cr b/src/crab.cr
index 7b4623d..61dc13e 100644
--- a/src/crab.cr
+++ b/src/crab.cr
@@ -3,9 +3,6 @@ require "option_parser"
 
 require "bitfield"
 require "sdl"
-require "imgui"
-require "imgui-backends"
-require "imgui-backends/lib"
 
 require "./crab/common/*"
 require "./crab/common/frontend/*"
diff --git a/src/crab/common/frontend.cr b/src/crab/common/frontend.cr
index b6ee78a..8857273 100644
--- a/src/crab/common/frontend.cr
+++ b/src/crab/common/frontend.cr
@@ -1,5 +1,3 @@
-require "lib_gl"
-
 abstract class Frontend
   def self.new(bios : String?, rom : String?, headless = false)
     if headless
diff --git a/src/crab/common/frontend/controllers/stubbed_controller.cr b/src/crab/common/frontend/controllers/stubbed_controller.cr
index f585ade..bae96ca 100644
--- a/src/crab/common/frontend/controllers/stubbed_controller.cr
+++ b/src/crab/common/frontend/controllers/stubbed_controller.cr
@@ -4,6 +4,7 @@ class StubbedController < Controller
   getter window_width : Int32 = 240
   getter window_height : Int32 = 160
   class_getter extensions = [] of String
+  class_getter shader : String? = "stubbed_colors.frag"
 
   def emu : Emu
     abort "Called emu method in StubbedController"
diff --git a/src/crab/common/frontend/sdl_opengl_imgui_frontend.cr b/src/crab/common/frontend/sdl_opengl_imgui_frontend.cr
index 3bfc1cd..3da976c 100644
--- a/src/crab/common/frontend/sdl_opengl_imgui_frontend.cr
+++ b/src/crab/common/frontend/sdl_opengl_imgui_frontend.cr
@@ -1,10 +1,15 @@
+require "imgui"
+require "imgui-backends"
+require "imgui-backends/lib"
+require "lib_gl"
+
 require "./controllers/*"
 require "./widgets/*"
 
 class SDLOpenGLImGuiFrontend < Frontend
   CONTROLLERS    = [StubbedController, GBController, GBAController]
   ROM_EXTENSIONS = CONTROLLERS.reduce([] of String) { |acc, controller| acc + controller.extensions }
-  SCALE          = 4
+  SCALE          = 3
   SHADERS        = "src/crab/common/shaders"
 
   @controller : Controller
@@ -270,13 +275,11 @@ class SDLOpenGLImGuiFrontend < Frontend
     shader = LibGL.create_shader(type)
     LibGL.shader_source(shader, 1, pointerof(source_ptr), nil)
     LibGL.compile_shader(shader)
-    shader_compiled = 0
-    LibGL.get_shader_iv(shader, LibGL::COMPILE_STATUS, pointerof(shader_compiled))
+    LibGL.get_shader_iv(shader, LibGL::COMPILE_STATUS, out shader_compiled)
     if shader_compiled != LibGL::TRUE
-      log_length = 0
-      LibGL.get_shader_iv(shader, LibGL::INFO_LOG_LENGTH, pointerof(log_length))
+      LibGL.get_shader_iv(shader, LibGL::INFO_LOG_LENGTH, out log_length)
       s = " " * log_length
-      LibGL.get_shader_info_log(shader, log_length, pointerof(log_length), s) if log_length > 0
+      LibGL.get_shader_info_log(shader, log_length, out _, s) if log_length > 0
       abort "Error compiling shader: #{s}"
     end
     shader
@@ -307,8 +310,7 @@ class SDLOpenGLImGuiFrontend < Frontend
 
     LibGL.blend_func(LibGL::SRC_ALPHA, LibGL::ONE_MINUS_SRC_ALPHA)
 
-    frame_buffer = 0_u32
-    LibGL.gen_textures(1, pointerof(frame_buffer))
+    LibGL.gen_textures(1, out frame_buffer)
     LibGL.active_texture(LibGL::TEXTURE0)
     LibGL.bind_texture(LibGL::TEXTURE_2D, frame_buffer)
     a = [LibGL::BLUE, LibGL::GREEN, LibGL::RED, LibGL::ONE] # flip the rgba to bgra where a is always 1
@@ -316,8 +318,7 @@ class SDLOpenGLImGuiFrontend < Frontend
     LibGL.tex_parameter_iv(LibGL::TEXTURE_2D, LibGL::TEXTURE_SWIZZLE_RGBA, a_ptr)
     LibGL.tex_parameter_i(LibGL::TEXTURE_2D, LibGL::TEXTURE_MIN_FILTER, LibGL::NEAREST)
     LibGL.tex_parameter_i(LibGL::TEXTURE_2D, LibGL::TEXTURE_MAG_FILTER, LibGL::NEAREST)
-    vao = 0_u32 # required even if not used in modern opengl
-    LibGL.gen_vertex_arrays(1, pointerof(vao))
+    LibGL.gen_vertex_arrays(1, out vao) # required even if not used in modern opengl
     LibGL.bind_vertex_array(vao)
 
     gl_context
diff --git a/src/crab/common/shaders/stubbed_colors.frag b/src/crab/common/shaders/stubbed_colors.frag
new file mode 100644
index 0000000..7814400
--- /dev/null
+++ b/src/crab/common/shaders/stubbed_colors.frag
@@ -0,0 +1,10 @@
+#version 330 core
+
+in vec2 tex_coord;
+out vec4 frag_color;
+
+uniform sampler2D input_texture;
+
+void main() {
+  frag_color = texture(input_texture, tex_coord);
+}